Bio

Bio


Dr. Montez-Rath completed her PhD in Biostatistics from Boston University in 2008 focusing on methods for modeling interaction effects in studies involving populations with high levels of comorbidity, such as persons on dialysis. She is a senior biostatistician and director of the Biostatistics Core of the Division of Nephrology at Stanford University where she has been collaborating with faculty and fellows since 2010 to study a variety of research questions relevant to kidney disease. Her methodological interests are mainly data-driven and include the handling of missing data, survival analysis with an emphasis on models for time-varying covariates and competing risks, methods for analyzing epidemiologic studies, analysis of correlated data and comparative effectiveness studies, as well as data visualization.

Current Role at Stanford


Director of the Biostatistics Core, Stanford Division of Nephrology (2016 - Present)

Honors & Awards


  • Anthony J. John Award for excellency in mathematics, University of Massachusetts, Dartmouth (1998)
  • Student Paper Award, American Statistical Association, Health Policy Statistics Section (2004)

Education & Certifications


  • Ph.D., Boston University, Biostatistics (2008)
  • M.S., University of Massachusetts, Amherst, Statistics (2001)
  • B.S., University of Massachusetts, Dartmouth, Computer oriented Mathematics (1999)

Professional

Professional Affiliations and Activities


  • Member, American Statistical Association (2005 - Present)

Publications

All Publications


  • Associations of Glycemic Control With Cardiovascular Outcomes Among US Hemodialysis Patients With Diabetes Mellitus. Journal of the American Heart Association Rhee, J. J., Zheng, Y., Montez-Rath, M. E., Chang, T. I., Winkelmayer, W. C. 2017; 6 (6)

    Abstract

    There is a lack of data on the relationship between glycemic control and cardiovascular end points in hemodialysis patients with diabetes mellitus.We included adult Medicare-insured patients with diabetes mellitus who initiated in-center hemodialysis treatment from 2006 to 2008 and survived for >90 days. Quarterly mean time-averaged glycated hemoglobin (HbA1c) values were categorized into <48 mmol/mol (<6.5%) (reference), 48 to <58 mmol/mol (6.5% to <7.5%), 58 to <69 mmol/mol (7.5% to <8.5%), and ?69 mmol/mol (?8.5%). Medicare claims were used to identify outcomes of cardiovascular mortality, nonfatal myocardial infarction (MI), fatal or nonfatal MI, stroke, and peripheral arterial disease. We used Cox models as a function of time-varying exposure to estimate multivariable adjusted hazard ratios and 95%CI for the associations between HbA1c and time to study outcomes in a cohort of 16 387 eligible patients. Patients with HbA1c 58 to <69 mmol/mol (7.5% to <8.5%) and ?69 mmol/mol (?8.5%) had 16% (CI, 2%, 32%) and 18% (CI, 1%, 37%) higher rates of cardiovascular mortality (P-trend=0.01) and 16% (CI, 1%, 33%) and 15% (CI, 1%, 32%) higher rates of nonfatal MI (P-trend=0.05), respectively, compared with those in the reference group. Patients with HbA1c ?69 mmol/mol (?8.5%) had a 20% (CI, 2%, 41%) higher rate of fatal or nonfatal MI (P-trend=0.02), compared with those in the reference group. HbA1c was not associated with stroke, peripheral arterial disease, or all-cause mortality.Higher HbA1c levels were significantly associated with higher rates of cardiovascular mortality and MI but not with stroke, peripheral arterial disease, or all-cause mortality in this large cohort of hemodialysis patients with diabetes mellitus.

    View details for DOI 10.1161/JAHA.117.005581

    View details for PubMedID 28592463

  • Persistent Gaps in Use of Advance Directives Among Nursing Home Residents Receiving Maintenance Dialysis. JAMA internal medicine Kurella Tamura, M., Liu, S., Montez-Rath, M. E., O'Hare, A. M., Hall, Y. N., Lorenz, K. A. 2017

    View details for DOI 10.1001/jamainternmed.2017.1618

    View details for PubMedID 28520863

  • Statin use and hip fractures in US kidney transplant recipients BMC NEPHROLOGY Vangala, C., Lenihan, C. R., Montez-Rath, M. E., Nair, S. S., Navaneethan, S. D., Ramanathan, V., Winkelmayer, W. C. 2017; 18

    Abstract

    Basic and translational research supports beneficial effects of statins on bone metabolism. Clinical studies suggest that statin use may reduce the risk of hip fractures in the general population. Whether statin use is associated with hip fracture risk in kidney transplant recipients, a particularly high-risk group for this outcome, is unknown.From the U.S. Renal Data System (2007-2011), we identified all hip fracture events recorded in Medicare billing claims of first-time kidney transplant recipients. We then matched all cases to an unlimited number of controls on age (±3 years), sex, race (black vs. non-black), and time since transplant. Cases and controls were required to have >1 year of Medicare Parts A?+?B?+?D coverage and be without a recorded history of hip fracture. We ascertained any statin use in the previous year and defined adherent statin use as those who had filled prescriptions for statins to cover >80% of days in that year (proportion of days covered, PDC). We ascertained several potential confounders (demographics, comorbidities, BMI, transplant-related factors) and applied conditional logistic regression with multiple imputation for missing data to estimate odds ratios (OR) and 95% confidence intervals (CI).We identified 231 hip fracture cases (mean age 51.8 years; 53% female; 11.3% black; 6.9 years from transplant, and 9.9 years from ESRD) and 15,575 matched controls. Any prior statin use was present in 64.1% of cases and 60.3% of controls with 37.2% of cases and 33.9% of controls being found adherent. Unadjusted conditional logistic regression showed an OR of 1.17 (0.89-1.54) for any statin use, and a fully-adjusted OR of 0.89 (0.67-1.19). Compared with statin non-users, the adjusted OR for patients with lesser adherence (PDC ?80%) and those with greater adherence (PDC >80%) were 0.93 (0.66-1.31) and 0.87 (0.63-1.20), respectively.Statin use was not associated with hip fracture risk in first-time kidney transplant recipients.

    View details for DOI 10.1186/s12882-017-0559-9

    View details for Web of Science ID 000400586100004

    View details for PubMedID 28460645

  • Proton Pump Inhibitor Use and Risk of Hip Fracture in Kidney Transplant Recipients AMERICAN JOURNAL OF KIDNEY DISEASES Lenihan, C. R., Nair, S. S., Vangala, C., Ramanathan, V., Montez-Rath, M. E., Winkelmayer, W. C. 2017; 69 (5): 595-601
  • Drug-Eluting Stents Versus Bare Metal Stents for Percutaneous Coronary Intervention in Kidney Transplant Recipients. Transplantation Lenihan, C. R., Montez-Rath, M. E., Winkelmayer, W. C., Chang, T. I. 2017; 101 (4): 851-857

    Abstract

    The comparative effectiveness of percutaneous coronary intervention (PCI) with drug-eluting stents (DES) versus bare metal stents (BMS) has not been studied in the kidney transplant population.Using the US Renal Data System, we identified 3245 kidney transplant patients who underwent PCI between April 2003 and December 2010; 2400 and 845 patients received DES and BMS, respectively. We used propensity score matching and inverse probability of treatment weighting to create DES- and BMS-treated groups whose observed baseline characteristics were well-balanced. The associations between stent type and the outcomes of (1) death; (2) death or myocardial infarction (MI); (3) death, MI, or repeat revascularization (RR); and (4) hospitalized bleeding were compared using Cox proportional hazards regression.Drug-eluting stent use increased during the study period, mirroring the trend described in the general population. In the propensity score-matched cohort, no significant association among DES (vs BMS) use and outcomes was observed at 1 and 2 years of follow-up. However, at 3 years, DES was associated with 20% (95% confidence interval [CI], 4-33%) lower risk of death, 15% (95% CI, 1-27%) lower risk of death or MI, and 14% (95% CI, 2-24%) lower risk of death, MI, or repeat revascularization. There were no significant differences in rates of hospitalized bleeding at any time point. Results were similar in the inverse probability of treatment weighting analysis.In this retrospective study of US kidney transplant recipients undergoing PCI, DES was associated with better clinical outcomes beyond 2 years of follow-up.

    View details for DOI 10.1097/TP.0000000000001446

    View details for PubMedID 27517730

  • Prevalence of chronic kidney disease and risk factors for its progression: A cross-sectional comparison of Indians living in Indian versus US cities PLOS ONE Anand, S., Kondal, D., Montez-Rath, M., Zheng, Y., Shivashankar, R., Singh, K., Gupta, P., Gupta, R., Ajay, V. S., Mohan, V., Pradeepa, R., Tandon, N., Ali, M. K., Narayan, K. M., Chertow, G. M., Kandula, N., Prabhakaran, D., Kanaya, A. M. 2017; 12 (3)

    Abstract

    While data from the latter part of the twentieth century consistently showed that immigrants to high-income countries faced higher cardio-metabolic risk than their counterparts in low- and middle-income countries, urbanization and associated lifestyle changes may be changing these patterns, even for conditions considered to be advanced manifestations of cardio-metabolic disease (e.g., chronic kidney disease [CKD]).Using cross-sectional data from the Center for cArdiometabolic Risk Reduction in South Asia (CARRS, n = 5294) and Mediators of Atherosclerosis in South Asians Living in America (MASALA, n = 748) studies, we investigated whether prevalence of CKD is similar among Indians living in Indian and U.S. cities. We compared crude, age-, waist-to-height ratio-, and diabetes- adjusted CKD prevalence difference. Among participants identified to have CKD, we compared management of risk factors for its progression. Overall age-adjusted prevalence of CKD was similar in MASALA (14.0% [95% CI 11.8-16.3]) compared with CARRS (10.8% [95% CI 10.0-11.6]). Among men the prevalence difference was low (prevalence difference 1.8 [95% CI -1.6,5.3]) and remained low after adjustment for age, waist-to-height ratio, and diabetes status (-0.4 [-3.2,2.5]). Adjusted prevalence difference was higher among women (prevalence difference 8.9 [4.8,12.9]), but driven entirely by a higher prevalence of albuminuria among women in MASALA. Severity of CKD--i.e., degree of albuminuria and proportion of participants with reduced glomerular filtration fraction--was higher in CARRS for both men and women. Fewer participants with CKD in CARRS were effectively treated. 4% of CARRS versus 51% of MASALA participants with CKD had A1c < 7%; and 7% of CARRS versus 59% of MASALA participants blood pressure < 140/90 mmHg. Our analysis applies only to urban populations. Demographic--particularly educational attainment--differences among participants in the two studies are a potential source of bias.Prevalence of CKD among Indians living in Indian and U.S. cities is similar. Persons with CKD living in Indian cities face higher likelihood of experiencing end-stage renal disease since they have more severe kidney disease and little evidence of risk factor management.

    View details for DOI 10.1371/journal.pone.0173554

    View details for Web of Science ID 000396311700041

    View details for PubMedID 28296920

  • Advance Directives and End-of-Life Care among Nursing Home Residents Receiving Maintenance Dialysis. Clinical journal of the American Society of Nephrology : CJASN Kurella Tamura, M., Montez-Rath, M. E., Hall, Y. N., Katz, R., O'Hare, A. M. 2017; 12 (3): 435-442

    Abstract

    Little is known about the relation between the content of advance directives and downstream treatment decisions among patients receiving maintenance dialysis. In this study, we determined the prevalence of advance directives specifying treatment limitations and/or surrogate decision-makers in the last year of life and their association with end-of-life care among nursing home residents.Using national data from 2006 to 2007, we compared the content of advance directives among 30,716 nursing home residents receiving dialysis to 30,825 nursing home residents with other serious illnesses during the year before death. Among patients receiving dialysis, we linked the content of advance directives to Medicare claims to ascertain site of death and treatment intensity in the last month of life.In the last year of life, 36% of nursing home residents receiving dialysis had a treatment-limiting directive, 22% had a surrogate decision-maker, and 13% had both in adjusted analyses. These estimates were 13%-27%, 5%-11%, and 6%-13% lower, respectively, than for decedents with other serious illnesses. For patients receiving dialysis who had both a treatment-limiting directive and surrogate decision-maker, the adjusted frequency of hospitalization, intensive care unit admission, intensive procedures, and inpatient death were lower by 13%, 17%, 13%, and 14%, respectively, and hospice use and dialysis discontinuation were 5% and 7% higher compared with patients receiving dialysis lacking both components.Among nursing home residents receiving dialysis, treatment-limiting directives and surrogates were associated with fewer intensive interventions and inpatient deaths, but were in place much less often than for nursing home residents with other serious illnesses.

    View details for DOI 10.2215/CJN.07510716

    View details for PubMedID 28057703

    View details for PubMedCentralID PMC5338713

  • Kidney Transplantation Rates Across Glomerulonephritis Subtypes in the United States. Transplantation O'Shaughnessy, M. M., Liu, S., Montez-Rath, M. E., Lafayette, R. A., Winkelmayer, W. C. 2017

    Abstract

    Whether kidney transplantation rates differ by glomerulonephritis (GN) subtype remains largely unknown.Using the US Renal Data System, we identified all adult patients with ESRD attributed to 1 of 6 GN subtypes who initiated dialysis in the US (1996-2013). Patients with diabetic nephropathy (DN) and autosomal-dominant polycystic kidney disease (ADPKD) served as "external" non-GN comparators. Using Cox proportional hazards regression, with death considered a competing risk, we estimated hazard ratios [HRs (95% confidence intervals)] for first kidney transplantation, controlling for year, demographics, comorbidities, socioeconomic factors, and Organ Procurement Organization (OPO).Among 718,480 patients studied, unadjusted and multivariable-adjusted transplant rates differed considerably across GN subtypes. Adjusted transplant rates were highest for patients with IgA nephropathy (IgAN, referent) and lower for all other groups: focal segmental glomerulosclerosis, HR=0.80 (0.77-0.82); membranous nephropathy, HR=0.88 (0.83-0.93); membranoproliferative GN, HR=0.84 (0.76-0.92); lupus nephritis, HR=0.69 (0.66-0.71); vasculitis, HR=0.66 (0.61-0.70); DN, HR=0.50 (0.47-0.52); ADPKD, HR=0.85 (0.82-0.88). Reduced kidney transplantation rates among comparator groups were driven more so by lower rates of waitlisting [HRs, vs. IgAN, ranged from 0.49 for DN to 0.92 for membranous nephropathy or ADPKD] than by lower rates of deceased donor kidney transplantation after waitlisting [rates were only significantly lower, vs. IgAN, for those with secondary GN subtypes: lupus nephritis, HR=0.91 (0.86-0.97), vasculitis, HR=0.85 (0.76-0.94); DN, HR=0.73 (0.69-0.77)].Identifying underlying reasons for apparent disease-specific barriers to kidney transplantation might inform center-specific transplant candidate selection procedures, along with national organ allocation policies, leading to more equitable patient care and improved patient outcomes.

    View details for DOI 10.1097/TP.0000000000001657

    View details for PubMedID 28207635

  • Kidney Transplantation Outcomes across GN Subtypes in the United States JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY O'Shaughnessy, M. M., Liu, S., Montez-Rath, M. E., Lenihan, C. R., Lafayette, R. A., Winkelmayer, W. C. 2017; 28 (2): 632-644

    Abstract

    Differences in kidney transplantation outcomes across GN subtypes have rarely been studied. From the US Renal Data System, we identified all adult (?18 years) first kidney transplant recipients (1996-2011) with ESRD attributed to one of six GN subtypes or two comparator kidney diseases. We computed hazard ratios (HRs) for death, all-cause allograft failure, and allograft failure excluding death as a cause (competing risks framework) using Cox proportional hazards regression. Among the 32,131 patients with GN studied, patients with IgA nephropathy (IgAN) had the lowest mortality rates and patients with IgAN or vasculitis had the lowest allograft failure rates. After adjusting for patient- and transplant-related factors, compared with IgAN (referent), FSGS, membranous nephropathy, membranoproliferative GN, lupus nephritis, and vasculitis associated with HRs (95% confidence intervals) for death of 1.57 (1.43 to 1.72), 1.52 (1.34 to 1.72), 1.76 (1.55 to 2.01), 1.82 (1.63 to 2.02), and 1.56 (1.34 to 1.81), respectively, and with HRs for allograft failure excluding death as a cause of 1.20 (1.12 to 1.28), 1.27 (1.14 to 1.41), 1.50 (1.36 to 1.66), 1.11 (1.02 to 1.20), and 0.94 (0.81 to 1.09), respectively. Considering external comparator groups, and comparing with IgAN, autosomal dominant polycystic kidney disease (ADPKD) and diabetic nephropathy associated with higher HRs for mortality [1.22 (1.12 to 1.34) and 2.57 (2.35 to 2.82), respectively], but ADPKD associated with a lower HR for allograft failure excluding death as a cause [0.85 (0.79 to 0.91)]. Reasons for differential outcomes by GN subtype and cause of ESRD should be examined in future research.

    View details for DOI 10.1681/ASN.2016020126

    View details for Web of Science ID 000393017600025

    View details for PubMedID 27432742

  • Estimating the Risk of Radiocontrast-Associated Nephropathy JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Wilhelm-Leen, E., Montez-Rath, M. E., Chertow, G. 2017; 28 (2): 653-659

    Abstract

    Estimates of the incidence of radiocontrast-associated nephropathy vary widely and suffer from misclassification of the cause of AKI and confounding. Using the Nationwide Inpatient Sample, we created multiple estimates of the risk of radiocontrast-associated nephropathy among adult patients hospitalized in the United States in 2009. First, we stratified patients according to the presence or absence of 12 relatively common diagnoses associated with AKI and evaluated the rate of AKI between strata. Next, we created a logistic regression model, controlling for comorbidity and acuity of illness, to estimate the risk of AKI associated with radiocontrast administration within each stratum. Finally, we performed an analysis stratified by the degree of preexisting comorbidity. In general, patients who received radiocontrast did not develop AKI at a clinically significant higher rate. Adjusted only for the complex survey design, patients to whom radiocontrast was and was not administered developed AKI at rates of 5.5% and 5.6%, respectively. After controlling for comorbidity and acuity of illness, radiocontrast administration associated with an odds ratio for AKI of 0.93 (95% confidence interval, 0.88 to 0.97). In conclusion, the risk of radiocontrast-associated nephropathy may be overstated in the literature and overestimated by clinicians. More accurate AKI risk estimates may improve clinical decision-making when attempting to balance the potential benefits of radiocontrast-enhanced imaging and the risk of AKI.

    View details for DOI 10.1681/ASN.2016010021

    View details for Web of Science ID 000393017600027

    View details for PubMedID 27688297

    View details for PubMedCentralID PMC5280012

  • Predicting mortality over different time horizons: which data elements are needed? Journal of the American Medical Informatics Association Goldstein, B. A., Pencina, M. J., Montez-Rath, M. E., Winkelmayer, W. C. 2017; 24 (1): 176-181

    Abstract

    Electronic health records (EHRs) are a resource for "big data" analytics, containing a variety of data elements. We investigate how different categories of information contribute to prediction of mortality over different time horizons among patients undergoing hemodialysis treatment.We derived prediction models for mortality over 7 time horizons using EHR data on older patients from a national chain of dialysis clinics linked with administrative data using LASSO (least absolute shrinkage and selection operator) regression. We assessed how different categories of information relate to risk assessment and compared discrete models to time-to-event models.The best predictors used all the available data (c-statistic ranged from 0.72-0.76), with stronger models in the near term. While different variable groups showed different utility, exclusion of any particular group did not lead to a meaningfully different risk assessment. Discrete time models performed better than time-to-event models.Different variable groups were predictive over different time horizons, with vital signs most predictive for near-term mortality and demographic and comorbidities more important in long-term mortality.

    View details for DOI 10.1093/jamia/ocw057

    View details for PubMedID 27357832

    View details for PubMedCentralID PMC5201182

  • Trends in Receipt of Intensive Procedures at the End of Life Among Patients Treated With Maintenance Dialysis AMERICAN JOURNAL OF KIDNEY DISEASES Eneanya, N. D., Hailpern, S. M., O'Hare, A. M., Tamura, M. K., Katz, R., Kreuter, W., Montez-Rath, M. E., Hebert, P. L., Hall, Y. N. 2017; 69 (1): 60-68
  • Proton Pump Inhibitor Use and Risk of Hip Fracture in Kidney Transplant Recipients. American journal of kidney diseases Lenihan, C. R., Nair, S. S., Vangala, C., Ramanathan, V., Montez-Rath, M. E., Winkelmayer, W. C. 2016

    Abstract

    Posttransplantation bone disease is a significant problem, with few well-evidenced therapeutic options. Proton pump inhibitors (PPIs) are associated with hip fracture in the general population and are widely prescribed for kidney transplant recipients.A case-control study.From the US Renal Data System, we identified from diagnoses and procedures 231 kidney transplant recipients with a first hip fracture. Cases were matched at the hip fracture index date with 15,575 controls on age, sex, race, and transplantation year.PPI use.First hip fracture.In the year prior to the index date, a PPI was prescribed to 65.4% of cases and 57.4% of controls. Additionally, in 34.6% of cases and 28.9% of controls, a PPI was prescribed for >80% of the year preceding the index date (higher PPI users). Unadjusted ORs of hip fracture associated with any and higher PPI use were 1.55 (95% CI, 1.18-2.05) and 1.65 (95% CI, 1.2-2.27), respectively. When adjusted for baseline demographic, clinical, and pharmacologic covariables, any and higher PPI use remained associated with hip fracture, with ORs of 1.39 (95% CI, 1.04-1.84) and 1.41 (95% CI, 1.02-1.95), respectively.Potential residual confounding through either incorrectly ascertained or unavailable confounders; cohort limited to Medicare beneficiaries receiving low-income subsidy.In summary, PPI use was associated with hip fracture risk in the US kidney transplant population.

    View details for DOI 10.1053/j.ajkd.2016.09.019

    View details for PubMedID 27866965

  • Re-evaluation of re-hospitalization and rehabilitation in renal research. Hemodialysis international. International Symposium on Home Hemodialysis Lin, E., Kurella Tamura, M., Montez-Rath, M. E., Chertow, G. M. 2016

    Abstract

    Introduction The use of administrative data to capture 30-day readmission rates in end-stage renal disease is challenging since Medicare combines claims from acute care, inpatient rehabilitation (IRF), and long-term care hospital stays into a single "Inpatient" file. For data prior to 2012, the United States Renal Data System does not contain the variables necessary to easily identify different facility types, making it likely that prior studies have inaccurately estimated 30-day readmission rates. Methods For this report, we developed two methods (a "simple method" and a "rehabilitation-adjusted method") to identify acute care, IRF, and long-term care hospital stays from United States Renal Data System claims data, and compared them to methods used in previously published reports. Findings We found that prior methods overestimated 30-day readmission rates by up to 12.3% and overestimated average 30-day readmission costs by up to 11%. In contrast, the simple and rehabilitation-adjusted methods overestimated 30-day readmission rates by 0.1% and average 30-day readmission costs by 1.8%. The rehabilitation-adjusted method also accurately identified 96.8% of IRF stays. Discussion Prior research has likely provided inaccurate estimates of 30-day readmissions in patients undergoing dialysis. In the absence of data on specific facility types particularly when using data prior to 2012, future researchers could employ our method to more accurately characterize 30-day readmission rates and associated outcomes in patients with end-stage renal disease.

    View details for DOI 10.1111/hdi.12497

    View details for PubMedID 27766736

  • Hip Fracture in Patients With Non-Dialysis-Requiring Chronic Kidney Disease. Journal of bone and mineral research Kim, S. M., Long, J., Montez-Rath, M., Leonard, M., Chertow, G. M. 2016; 31 (10): 1803-1809

    Abstract

    Patients with end-stage renal disease (ESRD) are at a high risk for hip fracture. Little is known about the risk for, and consequences of, hip fracture among patients with non-dialysis-requiring chronic kidney disease (CKD). We examined the incidence of hip fracture, in-hospital mortality, length of stay, and costs among patients with ESRD, non-dialysis-requiring CKD, and normal or near normal kidney function. Using the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample, a nationally representative database, we identified hospitalizations for hip fracture in 2010. We incorporated data from the United States Renal Data System (USRDS) and the US census to calculate population-specific rates. Age-standardized incidence of hip fracture was highest among patients with ESRD (3.89/1000 person-years), followed by non-dialysis-requiring CKD (1.81/1000 persons) and patients with normal or near normal kidney function (1.18/1000 persons). In-hospital mo rtality (odds ratio [OR]?=?1.69, 95% confidence interval [CI] 1.46 to 1.96), lengths of stay (median [10th, 90th percentiles] 5 [3 to 11] versus 5 [3 to 10] days) and costs (median $14,807 versus $13,314) were significantly higher in patients with non-dialysis-requiring CKD relative to patients with normal or near normal kidney function. In summary, non-dialysis-requiring CKD is associated with higher age-standardized rates of hip fracture and post-hip fracture mortality and higher resource utilization. © 2016 American Society for Bone and Mineral Research.

    View details for DOI 10.1002/jbmr.2862

    View details for PubMedID 27145189

  • Multivariate Risk Adjustment of Primary Care Patient Panels in a Public Health Setting: A Comparison of Statistical Models. The Journal of ambulatory care management Hirozawa, A. M., Montez-Rath, M. E., Johnson, E. C., Solnit, S. A., Drennan, M. J., Katz, M. H., Marx, R. 2016; 39 (4): 333-342

    Abstract

    We compared prospective risk adjustment models for adjusting patient panels at the San Francisco Department of Public Health. We used 4 statistical models (linear regression, two-part model, zero-inflated Poisson, and zero-inflated negative binomial) and 4 subsets of predictor variables (age/gender categories, chronic diagnoses, homelessness, and a loss to follow-up indicator) to predict primary care visit frequency. Predicted visit frequency was then used to calculate patient weights and adjusted panel sizes. The two-part model using all predictor variables performed best (R = 0.20). This model, designed specifically for safety net patients, may prove useful for panel adjustment in other public health settings.

    View details for DOI 10.1097/JAC.0000000000000065

    View details for PubMedID 27576054

  • Trends in Receipt of Intensive Procedures at the End of Life Among Patients Treated With Maintenance Dialysis. American journal of kidney diseases Eneanya, N. D., Hailpern, S. M., O'Hare, A. M., Kurella Tamura, M., Katz, R., Kreuter, W., Montez-Rath, M. E., Hebert, P. L., Hall, Y. N. 2016

    Abstract

    Many dialysis patients receive intensive procedures intended to prolong life at the very end of life. However, little is known about trends over time in the use of these procedures. We describe temporal trends in receipt of inpatient intensive procedures during the last 6 months of life among patients treated with maintenance dialysis.Mortality follow-back study.649,607 adult Medicare beneficiaries on maintenance dialysis therapy who died in 2000 to 2012.Period of death (2000-2003, 2004-2008, or 2009-2012), age at time of death (18-59, 60-64, 65-69, 70-74, 75-79, 80-84, and ?85 years), and race/ethnicity (Hispanic, non-Hispanic black, or non-Hispanic white).Receipt of an inpatient intensive procedure (defined as invasive mechanical ventilation/intubation, tracheostomy, gastrostomy/jejunostomy tube insertion, enteral or parenteral nutrition, or cardiopulmonary resuscitation) during the last 6 months of life.Overall, 34% of cohort patients received an intensive procedure in the last 6 months of life, increasing from 29% in 2000 to 36% in 2012 (with 2000-2003 as the referent category; adjusted risk ratios [RRs] were 1.06 [95% CI, 1.05-1.07] and 1.10 [95% CI, 1.09-1.12] for 2004-2008 and 2009-2012, respectively). Use of intensive procedures increased more markedly over time in younger versus older patients (comparing 2009-2012 to 2000-2003, adjusted RR was 1.18 [95% CI, 1.15-1.20] for the youngest age group as opposed to 1.00 [95% CI, 0.96-1.04] for the oldest group). Comparing 2009 to 2012 to 2000 to 2003, the use of intensive procedures increased more dramatically for Hispanic patients than for non-Hispanic black or non-Hispanic white patients (adjusted RRs of 1.18 [95% CI, 1.14-1.22], 1.09 [95% CI, 1.07-1.11], and 1.10 [95% CI, 1.08-1.12], respectively).Data sources do not provide insight into reasons for observed trends in the use of intensive procedures.Among patients treated with maintenance dialysis, there is a trend toward more frequent use of intensive procedures at the end of life, especially in younger patients and those of Hispanic ethnicity.

    View details for DOI 10.1053/j.ajkd.2016.07.028

    View details for PubMedID 27693262

  • Antihypertensive Medication Use in Older Patients Transitioning from Chronic Kidney Disease to End-Stage Renal Disease on Dialysis. Clinical journal of the American Society of Nephrology Chang, T. I., Zheng, Y., Montez-Rath, M. E., Winkelmayer, W. C. 2016; 11 (8): 1401-1412

    Abstract

    The transition from CKD to ESRD can be particularly unstable, with high rates of death and hospitalizations. Few studies have examined medication use during this critical period. We examined patterns of antihypertensive medication use from the four quarters before and eight quarters after incident ESRD treated with maintenance dialysis.We used the US Renal Data System to identify patients aged ?67 years initiating dialysis for ESRD between January 2008 and December 2010 with Medicare Part D and a low-income subsidy. We ascertained the incidence of AKI and hyperkalemia during each quarter on the basis of having at least 1 payment claim for the condition. We used Poisson regression with robust SEMs to formally test for changes in the trend and level of antihypertensive medication use in a series of intervention analyses.The number of antihypertensive drugs used increased as patients neared ESRD, peaking at an average of 3.4 in the quarter immediately preceding dialysis initiation, then declining to 2.2 medications by 2 years later. Angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use was stable at approximately 40%, even among patients with coronary disease and systolic heart failure, and did not correlate with AKI or hyperkalemia. Dialysis initiation was associated with a 40% (95% confidence interval, 38% to 43%) lower adjusted level of diuretic use, which continued to decline after ESRD. Three- and four-drug combinations that included a diuretic were most common before ESRD, whereas after ESRD, one- and two-drug ?-blocker or calcium-channel blocker-based combinations were most common.The use of antihypertensive medications, particularly angiotensin-converting enzyme inhibitor/angiotensin II receptor blockers and diuretics, may be suboptimal during the transition from CKD to ESRD, especially in patients with coronary disease or systolic heart failure. Future studies are needed to identify strategies to increase the appropriate use of antihypertensive medications during this critical transition period.

    View details for DOI 10.2215/CJN.10611015

    View details for PubMedID 27354656

  • Recovery From Acute Kidney Injury and CKD Following Heart Transplantation in Children, Adolescents, and Young Adults: A Retrospective Cohort Study. American journal of kidney diseases Hollander, S. A., Montez-Rath, M. E., Axelrod, D. M., Krawczeski, C. D., May, L. J., Maeda, K., Rosenthal, D. N., Sutherland, S. M. 2016; 68 (2): 212-218

    Abstract

    Acute kidney injury (AKI) is common in children following surgery for congenital heart disease and has been associated with poor long-term kidney outcomes. Children undergoing heart transplantation may be at increased risk for the development of both AKI and chronic kidney disease (CKD). This study examines AKI rates in children, adolescents, and young adults after heart transplantation and analyzes the relationship between AKI and CKD in this population.Retrospective cohort study.88 young patients who underwent heart transplantation at Lucile Packard Children's Hospital, Stanford, CA, September 1, 2007, to November 30, 2013.The primary independent variable was AKI within the first 7 postoperative days, ascertained according to the KDIGO (Kidney Disease: Improving Global Outcomes) creatinine criteria (increase in serum creatinine ? 1.5 times baseline within 7 days).Recovery from AKI at 3 months, ascertained as serum creatinine level < 1.5 times baseline; and development of CKD at 6 and 12 months, ascertained as estimated glomerular filtration rate < 60mL/min/1.73m(2) for more than 3 months.63 (72%) patients developed AKI; 57% had moderate (stage 2 or severe stage 3) disease. Recovery occurred in 39 of 63 (62%), 50% for stage 2 or 3 versus 78% for stage 1 (P=0.04). At 6 and 12 months, 3 of 82 (4%) and 4 of 76 (5%) developed CKD, respectively. At both time points, CKD was more common in those without recovery (3/22 [14%] vs 0/38 (0%); P=0.04, and 3/17 (18%) vs (0/34) 0%; P=0.03, respectively).Retrospective design, small sample size, and single-center nature of the study.AKI is common after heart transplantation in children, adolescents, and young adults. Nonrecovery from AKI is more common in patients with more severe AKI and is associated with the development of CKD during the first year.

    View details for DOI 10.1053/j.ajkd.2016.01.024

    View details for PubMedID 26970941

  • Rates and Outcomes of Parathyroidectomy for Secondary Hyperparathyroidism in the United States CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Kim, S. M., Long, J., Montez-Rath, M. E., Leonard, M. B., Norton, J. A., Chertow, G. M. 2016; 11 (7): 1260-1267

    Abstract

    Secondary hyperparathyroidism is common among patients with ESRD. Although medical therapy for secondary hyperparathyroidism has changed dramatically over the last decade, rates of parathyroidectomy for secondary hyperparathyroidism across the United States population are unknown. We examined temporal trends in rates of parathyroidectomy, in-hospital mortality, length of hospital stay, and costs of hospitalization.Using the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample, a representative national database on hospital stay regardless of age and payer in the United States, we identified parathyroidectomies for secondary hyperparathyroidism from 2002 to 2011. Data from the US Renal Data System reports were used to calculate the rate of parathyroidectomy.We identified 32,971 parathyroidectomies for secondary hyperparathyroidism between 2002 and 2011. The overall rate of parathyroidectomy was approximately 5.4/1000 patients (95% confidence interval [95% CI], 5.0/1000 to 6.0/1000). The rate decreased from 2003 (7.9/1000 patients; 95% CI, 6.2/1000 to 9.6/1000), reached a nadir in 2005 (3.3/1000 patients; 95% CI, 2.6/1000 to 4.0/1000), increased again through 2006 (5.4/1000 patients; 95% CI, 4.4/1000 to 6.4/1000), and remained stable since that time. Rates of in-hospital mortality decreased from 1.7% (95% CI, 0.8% to 2.6%) in 2002 to 0.8% (95% CI, 0.1% to 1.6%) in 2011 (P for trend <0.001). In-hospital mortality rates were significantly higher in patients with heart failure (odds ratio [OR], 4.23; 95% CI, 2.59 to 6.91) and peripheral vascular disease (OR, 4.59; 95% CI, 2.75 to 7.65) and lower among patients with prior kidney transplantation (OR, 0.20; 95% CI, 0.06 to 0.65).Despite the use of multiple medical therapies, rates of parathyroidectomy of secondary hyperparathyroidism have not declined in recent years.

    View details for DOI 10.2215/CJN.10370915

    View details for Web of Science ID 000379195500019

    View details for PubMedID 27269300

  • The win ratio approach to analyzing composite outcomes: An application to the EVOLVE trial CONTEMPORARY CLINICAL TRIALS Abdalla, S., Montez-Rath, M. E., Parfrey, P. S., Chertow, G. M. 2016; 48: 119-124

    Abstract

    Unlike conventional time-to-event analysis of composite endpoints in clinical trials, the "win ratio" method allows for flexibility in prioritizing their components. Here, we compare the EVOLVE trial findings using the win ratio with those from time-to-event analysis.Randomization to cinacalcet or placebo.The primary composite endpoint combining all-cause mortality and non-fatal myocardial infarction, hospitalization for unstable angina, heart failure, and peripheral vascular events.In an unadjusted analysis, we paired each participant from the cinacalcet arm with every participant from the placebo arm within randomization strata. Pairs were classified as "winners" or "losers," according to which participant died first during the shared follow-up time, or experienced the next ranked event first. We ranked non-fatal events in two ways: 1) all ranked evenly; and 2) prioritized by their effect on health-related quality of life. The win ratio equaled the total winners divided by total losers. Further analyses were conducted where the win ratio was stratified by, or adjusted for, age.The unadjusted win ratio for the primary composite endpoint was 1.09 (95% CI 0.97 to 1.21), a statistically non-significant result which supports the primary trial result - unadjusted hazard ratio 0.93 (95% CI 0.85 to 1.02). Age-stratified analyses showed a nominally significant benefit of cinacalcet (win ratio 1.14, 95% CI 1.04 to 1.26). Ranking of non-fatal outcomes by their relative effects on quality of life did not materially alter the results.The win ratio method corroborated the findings of EVOLVE based on conventional time-to-event analysis. EVOLVE ClinicalTrials.gov number: NCT00345839.

    View details for DOI 10.1016/j.cct.2016.04.001

    View details for Web of Science ID 000378458900016

    View details for PubMedID 27080930

  • Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and cardiovascular outcomes in patients initiating peritoneal dialysis. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association Shen, J. I., Saxena, A. B., Montez-Rath, M. E., Chang, T. I., Winkelmayer, W. C. 2016

    Abstract

    Data on the effectiveness of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) in reducing cardiovascular (CV) risk in patients undergoing peritoneal dialysis (PD) are limited. We investigated the association between ACEI/ARB use and CV outcomes in patients initiating PD.In this observational cohort study, we identified from the United States Renal Data System all adult patients who initiated PD from 2007 to 2011 and participated in Medicare Part D, a federal prescription drug benefits program, for the first 90 days of dialysis. Patients who filled a prescription for an ACEI or ARB in those 90 days were considered users. We applied Cox regression to an inverse probability of treatment weighted cohort to estimate the hazard ratios (HRs) for the combined outcome of death, ischemic stroke or myocardial infarction (MI) and each outcome individually.Among 4879 patients, 2063 (42%) used an ACEI/ARB. Patients were followed up for a median of 1.2 years. We recorded 1771 events, for a composite rate of 25 events per 100 person-years. ACEI/ARB use (versus nonuse) was associated with a reduced risk of the composite outcome {HR 0.84 [95% confidence interval (CI) 0.76-0.93]}, all-cause mortality [HR 0.83 (95% CI 0.75-0.92)] and CV death [HR 0.74 (95% CI 0.63-0.87)], but not MI [HR 0.88 (95% CI 0.69-1.12)] or ischemic stroke [HR 1.06 (95% CI 0.79-1.43)]. Results were similar in as-treated analyses. In a subgroup analysis, we did not find any effect modification by residual renal function.ACEI/ARB use is common in patients initiating PD and is associated with a lower risk of fatal CV outcomes.

    View details for PubMedID 27190342

  • Impact of ventricular assist device placement on longitudinal renal function in children with end-stage heart failure. journal of heart and lung transplantation May, L. J., Montez-Rath, M. E., Yeh, J., Axelrod, D. M., Chen, S., Maeda, K., Almond, C. S., Rosenthal, D. N., Hollander, S. A., Sutherland, S. M. 2016; 35 (4): 449-456

    Abstract

    Although ventricular assist devices (VADs) restore hemodynamics in those with heart failure, reversibility of end-organ dysfunction with VAD support is not well characterized. Renal function often improves in adults after VAD placement, but this has not been comprehensively explored in children.Sixty-three children on VAD support were studied. Acute kidney injury (AKI) was defined by Kidney Disease: Improving Global Outcomes criteria. Estimated glomerular filtration rate (eGFR) was determined by the Schwartz method. Generalized linear mixed-effects models compared the pre-VAD and post-VAD eGFR for the cohort and sub-groups with and without pre-VAD renal dysfunction (pre-VAD eGFR < 90 ml/min/1.73 m(2)).The pre-VAD eGFR across the cohort was 84.0 ml/min/1.73 m(2) (interquartile range [IQR] 62.3-122.7), and 55.6% (34 of 63) had pre-VAD renal dysfunction. AKI affected 60.3% (38 of 63), with similar rates in those with and without pre-existing renal dysfunction. Within the cohort, the nadir eGFR occurred 1 day post-operatively (62.9 ml/min/1.73 m(2); IQR, 51.2-88.9 ml/min/1.73 m(2); p < 0.001). By Day 5, however, the eGFR exceeded the baseline (99.0 ml/min/1.73 m(2); IQR, 59.3-146.7 ml/min/1.73 m(2); p = 0.03) and remained significantly higher through the first post-operative week. After adjusting for age, gender, and AKI, the eGFR continued to increase throughout the entire 180-day study period (? = 0.0025; 95% confidence interval, 0.0015-0.0036; p < 0.001). Patients with pre-VAD renal dysfunction experienced the greatest improvement in the eGFR (? = 0.0051 vs ? = 0.0013, p < 0.001).Renal dysfunction is prevalent in children with heart failure undergoing VAD placement. Although peri-operative AKI is common, renal function improves substantially in the first post-operative week and for months thereafter. This is particularly pronounced in those with pre-VAD renal impairment, suggesting that VADs may facilitate recovery and maintenance of kidney function in children with advanced heart failure.

    View details for DOI 10.1016/j.healun.2015.10.039

    View details for PubMedID 26653933

  • Differences in Initial Hemodialysis Vascular Access Use Among Glomerulonephritis Subtypes in the United States. American journal of kidney diseases O'Shaughnessy, M. M., Montez-Rath, M. E., Zheng, Y., Lafayette, R. A., Winkelmayer, W. C. 2016; 67 (4): 638-647

    Abstract

    The type of vascular access used for hemodialysis affects patient morbidity and mortality. Whether vascular access types differ by glomerulonephritis (GN) subtype in the US hemodialysis population has not been investigated.Cross-sectional observational study.We identified all adult (aged ? 18 years) patients within the US Renal Data System who initiated hemodialysis therapy from July 2005 through December 2011 with a diagnosis of end-stage renal disease attributed to any of 4 primary (focal segmental glomerulosclerosis, immunoglobulin A nephropathy [reference group], membranous nephropathy, and membranoproliferative GN) or 2 secondary (lupus nephritis and vasculitis) GN subtypes.GN subtype.ORs with 95% CIs for arteriovenous fistula versus central venous catheter (CVC) use and for arteriovenous graft versus CVC use were computed using multinomial logistic regression, with adjustment for demographic, socioeconomic, comorbidity, and duration of nephrology care covariates.Among 29,015 patients, CVC use at initiation of hemodialysis therapy was substantially higher in patients with lupus nephritis (89.2%) or vasculitis (91.2%) compared with patients with primary GN subtypes (72.7%-79.8%). After adjustment and compared with patients with immunoglobulin A nephropathy, patients with lupus nephritis or vasculitis were as likely to have used an arteriovenous graft (ORs of 0.94 [95% CI, 0.70-1.27] and 0.80 [95% CI, 0.56-1.13], respectively) but significantly less likely to have used an arteriovenous fistula (ORs of 0.66 [95% CI, 0.57-0.76] and 0.54 [95% CI, 0.45-0.63], respectively), whereas patients with any comparator primary GN subtype were at least as likely to have used either of these 2 access types.Potential misclassification of exposure; residual confounding by unmeasured covariates; inability to determine causes of observed associations; lacking longitudinal data for vascular access use.Significant differences in vascular access distributions at initiation of hemodialysis therapy are apparent among GN subtypes. The unacceptably high use of CVCs in patients with lupus nephritis and vasculitis is particularly concerning. Further studies are needed to identify any potentially modifiable factors underlying these findings.

    View details for DOI 10.1053/j.ajkd.2015.11.019

    View details for PubMedID 26774466

  • Drug-Eluting Versus Bare-Metal Stents During PCI in Patients With End-Stage Renal Disease on Dialysis JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Chang, T. I., Montez-Rath, M. E., Tsai, T. T., Hlatky, M. A., Winkelmayer, W. C. 2016; 67 (12): 1459-1469
  • Sleep disordered breathing and cardiovascular risk in older patients initiating dialysis in the United States: a retrospective observational study using medicare data BMC NEPHROLOGY Tuohy, C. V., Montez-Rath, M. E., Turakhia, M., Chang, T. I., Winkelman, J. W., Winkelmayer, W. C. 2016; 17
  • Differences in initial treatment modality for end-stage renal disease among glomerulonephritis subtypes in the USA. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association O'Shaughnessy, M. M., Montez-Rath, M. E., Lafayette, R. A., Winkelmayer, W. C. 2016; 31 (2): 290-298

    Abstract

    Kidney transplantation is the preferred treatment for end-stage renal disease (ESRD), while peritoneal dialysis affords certain benefits over hemodialysis. Distributions and determinants of first ESRD treatment modality have not been compared across glomerulonephritis (GN) subtypes.We identified all adult (18-75 years) patients with ESRD attributed to any of six GN subtypes [focal segmental glomerulosclerosis (FSGS), IgA nephropathy (IgAN), membranous nephropathy (MN), membranoproliferative GN (MPGN), lupus nephritis (LN) and vasculitis] who were first registered in the US Renal Data System (USRDS) between 1996 and 2011. We used multinomial logistic regression-adjusting for temporal, geographic, demographic, socioeconomic and comorbid factors-to determine odds ratios (ORs) with 95% confidence intervals (CIs) for transplantation versus hemodialysis, and for peritoneal dialysis versus hemodialysis, comparing other GN subtypes to IgAN.Among the 75 278 patients studied, patients with comparator GN subtypes were significantly less likely than those with IgAN to receive either transplantation or peritoneal dialysis. After adjusting for potentially confounding covariates, patients with comparator primary GN subtypes (FSGS, MN, MPGN) were at least as likely to receive transplantation [FSGS OR 0.98 (95% CI 0.93-1.15), MN OR 1.19 (95% CI 1.01-1.39), MPGN OR 1.08 (95% CI 0.93-1.26)] or peritoneal dialysis [FSGS OR 1.05 (95% CI 0.98-1.12), MN OR 1.30 (95% CI 1.18-1.43), MPGN OR 0.95 (95% CI 0.85-1.06)] as patients with IgAN. Conversely, patients with the secondary GN subtypes LN and vasculitis remained significantly less likely to receive either modality [transplantation OR 0.49 (95% CI 0.43-0.56) for LN and 0.27 (95% CI 0.22-0.34) for vasculitis, peritoneal dialysis OR 0.76 (95% CI 0.70-0.82) for LN and 0.54 (95% CI 0.48-0.60) for vasculitis].Significant differences in ESRD treatment practice patterns are apparent among GN subtypes. To ensure equitable care for all patients, regardless of GN subtype, reasons for observed disparities should be elucidated and-if appropriate-eliminated.

    View details for DOI 10.1093/ndt/gfv386

    View details for PubMedID 26610594

  • Declining Rates of Inpatient Parathyroidectomy for Primary Hyperparathyroidism in the US. PloS one Kim, S. M., Shu, A. D., Long, J., Montez-Rath, M. E., Leonard, M. B., Norton, J. A., Chertow, G. M. 2016; 11 (8)

    Abstract

    Parathyroidectomy is the only curative therapy for patients with primary hyperparathyroidism. However, the incidence, correlates and consequences of parathyroidectomy for primary hyperparathyroidism across the entire US population are unknown. We evaluated temporal trends in rates of inpatient parathyroidectomy for primary hyperparathyroidism, and associated in-hospital mortality, length of stay, and costs. We used the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS) from 2002-2011. Parathyroidectomies for primary hyperparathyroidism were identified using International Classification of Diseases, Ninth Revision codes. Unadjusted and age- and sex- adjusted rates of inpatient parathyroidectomy for primary hyperparathyroidism were derived from the NIS and the annual US Census. We estimated 109,583 parathyroidectomies for primary hyperparathyroidism between 2002 and 2011. More than half (55.4%) of patients were younger than age 65, and more than three-quarters (76.8%) were female. The overall rate of inpatient parathyroidectomy was 32.3 cases per million person-years. The adjusted rate decreased from 2004 (48.3 cases/million person-years) to 2007 (31.7 cases/million person-years) and was sustained thereafter. Although inpatient parathyroidectomy rates declined over time across all geographic regions, a steeper decline was observed in the South compared to other regions. Overall in-hospital mortality rates were 0.08%: 0.02% in patients younger than 65 years and 0.14% in patients 65 years and older. Inpatient parathyroidectomy rates for primary hyperparathyroidism have declined in recent years.

    View details for DOI 10.1371/journal.pone.0161192

    View details for PubMedID 27529699

  • Trends in the outcomes of end-stage renal disease secondary to human immunodeficiency virus-associated nephropathy. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association Razzak Chaudhary, S., Workeneh, B. T., Montez-Rath, M. E., Zolopa, A. R., Klotman, P. E., Winkelmayer, W. C. 2015; 30 (10): 1734-1740

    Abstract

    Little is known about the trends in the incidence and outcomes of patients with end-stage renal disease (ESRD) attributed to human immunodeficiency virus-associated nephropathy (HIVAN). We sought to define relative incidence among ESRD patients, changes in mortality among patients with ESRD attributed to HIVAN, as well as changes in the excess mortality experienced by patients with ESRD attributed to HIVAN compared with otherwise similar ESRD patients with non-HIVAN causes.We used the US Renal Data System to identify all individuals with reported HIVAN who initiated treatment for ESRD between 1989 and 2011. We plotted their counts and proportions among all incident ESRD patients and tabulated their characteristics across years. We then compared mortality within the HIVAN group across years using Cox regression. In addition, we studied the trends in relative mortality of HIVAN patients versus those with ESRD not reported as HIVAN.Overall, 14 719 individuals with HIVAN-ESRD were recorded, with significant reductions in recent years (893 in 2006; 525 in 2011). Compared with patients initiating dialysis between 1989 and 1992, mortality declined by 40% (HR = 0.60; 95% CI, 0.55-0.65) and 64% (HR = 0.36; 95% CI, 0.32-0.40) for patients initiating dialysis in 1999/2000 and 2009-11, respectively. The adjusted excess mortality of HIVAN-ESRD patients versus incident ESRD patients from other causes was >5-fold in 1989-92 (HR = 5.21; 95% CI, 4.84-5.60); this excess mortality has subsequently declined but remained at almost 3-fold in recent years (e.g. HR = 2.58; 95% CI, 2.37-2.80, 2009-11 incidence cohort).Concurrent with the increasing availability of highly active antiretroviral therapy (HAART), both the incidence of ESRD due to HIVAN and the mortality of such patients have decreased substantially. However, HIVAN patients reaching ESRD continue to experience substantial excess mortality compared with other ESRD patients even in the current era of modern HAART.

    View details for DOI 10.1093/ndt/gfv207

    View details for PubMedID 26175146

  • Trends in the outcomes of end-stage renal disease secondary to human immunodeficiency virus-associated nephropathy NEPHROLOGY DIALYSIS TRANSPLANTATION Chaudhary, S. R., Workeneh, B. T., Montez-Rath, M. E., Zolopa, A. R., Klotman, P. E., Winkelmayer, W. C. 2015; 30 (10): 1734-1740

    View details for DOI 10.1093/ndt/gfv207

    View details for Web of Science ID 000363171900019

  • Outcomes After Warfarin Initiation in a Cohort of Hemodialysis Patients With Newly Diagnosed Atrial Fibrillation. American journal of kidney diseases Shen, J. I., Montez-Rath, M. E., Lenihan, C. R., Turakhia, M. P., Chang, T. I., Winkelmayer, W. C. 2015; 66 (4): 677-688

    Abstract

    Although warfarin is indicated to prevent ischemic strokes in most patients with atrial fibrillation (AF), evidence supporting its use in hemodialysis patients is limited. Our aim was to examine outcomes after warfarin therapy initiation, relative to no warfarin use, following incident AF in a large cohort of hemodialysis patients who had comprehensive prescription drug coverage through Medicare Part D.Retrospective observational cohort study.Patients in the US Renal Data System undergoing maintenance hemodialysis who had AF newly diagnosed in 2007 to 2011, with Medicare Part D coverage, who had no recorded history of warfarin use.Warfarin therapy initiation, identified by a filled prescription within 30 days of the AF event.Death, ischemic stroke, hemorrhagic stroke, severe gastrointestinal bleeding, and composite outcomes.HRs estimated by applying Cox regression to an inverse probability of treatment and censoring-weighted cohort.Of 12,284 patients with newly diagnosed AF, 1,838 (15%) initiated warfarin therapy within 30 days; however, ?70% discontinued its use within 1 year. In intention-to-treat analyses, warfarin use was marginally associated with a reduced risk of ischemic stroke (HR, 0.68; 95% CI, 0.47-0.99), but not with the other outcomes. In as-treated analyses, warfarin use was associated with reduced mortality (HR, 0.84; 95% CI, 0.73-0.97).Short observation period, limited number of nonfatal events, limited generalizability of results to more affluent patients.In hemodialysis patients with incident AF, warfarin use was marginally associated with reduced risk of ischemic stroke, and there was a signal toward reduced mortality in as-treated analyses. These results support clinical equipoise regarding the use of warfarin in hemodialysis patients and underscore the need for randomized trials to fill this evidence gap.

    View details for DOI 10.1053/j.ajkd.2015.05.019

    View details for PubMedID 26162653

  • Patient Characteristics and Outcomes by GN Subtype in ESRD. Clinical journal of the American Society of Nephrology O'Shaughnessy, M. M., Montez-Rath, M. E., Lafayette, R. A., Winkelmayer, W. C. 2015; 10 (7): 1170-1178

    Abstract

    Outcomes-based research rarely focuses on patients with ESRD caused by GN. The hypotheses were that the GN subtype would clinically discriminate patient groups and independently associate with survival after ESRD therapy initiation.Data were extracted from the US Renal Data System for adult patients with incident (1996-2011) ESRD attributed to six GN subtypes: FSGS, IgA nephropathy (IgAN), membranous nephropathy, membranoproliferative glomeruonephritis, lupus nephritis (LN), and vasculitis. ESRD attributed to diabetes and autosomal dominant polycystic kidney disease served as non-GN comparators. Unadjusted and adjusted mortality hazard ratios (aHRs) with 95% confidence intervals (95% CIs) were estimated using Cox regression (reference, IgAN). Models sequentially adjusted for sociodemographic (model 2), comorbidity/laboratory (model 3), and ESRD treatment modality (model 4) variables.Among 84,301 patients with ESRD attributed to GN, the median age ranged from 39 (LN) to 66 (vasculitis) years, male sex ranged from 18% (LN) to 68% (IgAN), and black race ranged from 7% (IgAN) to 49% (LN). Patients with IgAN had the fewest comorbidities and lowest use of hemodialysis (70.1%). After a median follow-up of 2.5 (interquartile range, 1.0-4.9) years, crude mortality was lowest in IgAN (3.7 deaths/100 person years). Compared to IgAN, adjusted mortality was highest in LN (model 4 aHR=1.75; 95% CI, 1.68 to 1.83) and in diabetes (aHR=1.73; 95% CI, 1.67 to 1.79), and was also higher in all other GN subtypes (membranous nephropathy: aHR=1.23; 95% CI, 1.17 to 1.29; FSGS: aHR=1.37; 95% CI, 1.32 to 1.42; membranoproliferative GN: aHR=1.38; 95% CI, 1.31 to 1.45; vasculitis: aHR=1.51; 95% CI, 1.45 to 1.58) and in autosomal dominant polycystic kidney disease (aHR=1.22; 95% CI, 1.18 to 1.27).This study exposes substantial heterogeneity across GN subtypes at ESRD therapy initiation and identifies independent associations between GN subtype and post-ESRD mortality. These survival discrepancies warrant further study, and the utility of current research practice to group GN subtypes together when evaluating ESRD outcomes should be questioned.

    View details for DOI 10.2215/CJN.11261114

    View details for PubMedID 26092830

    View details for PubMedCentralID PMC4491300

  • Prevalence of chronic kidney disease in two major Indian cities and projections for associated cardiovascular disease KIDNEY INTERNATIONAL Anand, S., Shivashankar, R., Ali, M. K., Kondal, D., Binukumar, B., Montez-Rath, M. E., Ajay, V. S., Pradeepa, R., Deepa, M., Gupta, R., Mohan, V., Narayan, K. M., Tandon, N., Chertow, G. M., Prabhakaran, D. 2015; 88 (1): 178-185

    Abstract

    India is experiencing an alarming rise in the burden of noncommunicable diseases, but data on the incidence of chronic kidney disease (CKD) are sparse. Using the Center for Cardiometabolic Risk Reduction in South Asia surveillance study (a population-based survey of Delhi and Chennai, India) we estimated overall, and age-, sex-, city-, and diabetes-specific prevalence of CKD, and defined the distribution of the study population by the Kidney Disease Improving Global Outcomes (KDIGO) classification scheme. The likelihood of cardiovascular events in participants with and without CKD was estimated by the Framingham and Interheart Modifiable Risk Scores. Of the 12,271 participants, 80% had complete data on serum creatinine and albuminuria. The prevalence of CKD and albuminuria, age standardized to the World Bank 2010 world population, was 8.7% (95% confidence interval: 7.9-9.4%) and 7.1% (6.4-7.7%), respectively. Nearly 80% of patients with CKD had an abnormally high hemoglobin A1c (5.7 and above). Based on KDIGO guidelines, 6.0, 1.0, and 0.5% of study participants are at moderate, high, or very high risk for experiencing CKD-associated adverse outcomes. The cardiovascular risk scores placed a greater proportion of patients with CKD in the high-risk categories for experiencing cardiovascular events when compared with participants without CKD. Thus, 1 in 12 individuals living in two of India's largest cities have evidence of CKD, with features that put them at high risk for adverse outcomes.

    View details for DOI 10.1038/ki.2015.58

    View details for Web of Science ID 000357138000023

    View details for PubMedID 25786102

  • Comparison of longer-term outcomes after kidney transplantation between Hispanic and non-Hispanic whites in the United States. American journal of transplantation Arce, C. M., Lenihan, C. R., Montez-Rath, M. E., Winkelmayer, W. C. 2015; 15 (2): 499-507

    Abstract

    Little is known about the longer-term kidney transplant outcomes in the rapidly growing Hispanic population. Using the United States Renal Data System, we identified 105?250 Caucasian patients who received a first kidney transplant between January 1, 1996 and December 31, 2010. We tested for differences between Hispanic and non-Hispanic patients in the outcomes of (1) mortality, (2) all-cause graft failure, and (3) graft failure excluding death with a functioning graft. We used Cox regression to estimate (with 95% confidence intervals) multivariable-adjusted cause-specific hazard ratios (aHRCS ) for mortality and all-cause graft failure and subdistribution hazard ratios (aHRSD ) accounting for death as a competing risk for graft failure excluding death with a functioning graft. Both mortality [aHRCS ?=?0.69 (0.65-0.73)] and all-cause graft failure [aHRCS ?=?0.79 (0.75-0.83)] were lower in Hispanics. The association between Hispanic ethnicity and graft failure excluding death was modified by age (p?

    View details for DOI 10.1111/ajt.13043

    View details for PubMedID 25556854

  • Correlates and outcomes of warfarin initiation in kidney transplant recipients newly diagnosed with atrial fibrillation. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association Lenihan, C. R., Montez-Rath, M. E., Shen, J. I., Scandling, J. D., Turakhia, M. P., Chang, T. I., Winkelmayer, W. C. 2015; 30 (2): 321-329

    Abstract

    In the kidney transplant population with atrial fibrillation (AF), evidence regarding the effectiveness and safety of warfarin treatment is lacking. We used fee-for-service Medicare claims to identify kidney transplant recipients with newly diagnosed AF from the United States Renal Data System. Warfarin use within 30 days of AF diagnosis was ascertained from Medicare Part D prescription claims (2007-11) or using a validated algorithm (1997-2011). The study end points were (i) the composite of death, stroke or gastrointestinal bleed, (ii) death and (iii) death-censored graft failure. Warfarin user and non-user groups were balanced using inverse probability of treatment weighting and hazard ratios were (HRs) estimated using Cox regression. Among 718 subjects with an indication for anticoagulation, 24% initiated warfarin treatment within 30 days of AF diagnosis. Age was the only independent correlate of warfarin use [odds ratio = 1.02 per year; 95% confidence interval (95% CI) 1.01-1.04]. In the larger cohort of 6492 patients with AF, warfarin use [(23.5%) versus non-use (76.5%)] was associated with small and non-significant reductions in the composite of death, stroke or gastrointestinal bleed (HR = 0.92; 95% CI 0.83-1.02), death (HR = 0.92; 95% CI 0.82-1.02) and death-censored graft failure (HR = 0.90; 95% CI 0.76-1.08). Our study suggests the need for clinical trials of warfarin use in the kidney transplant population with AF.

    View details for DOI 10.1093/ndt/gfu323

    View details for PubMedID 25335507

  • Thienopyridine use after coronary stenting in low income patients enrolled in medicare part D receiving maintenance dialysis. Journal of the American Heart Association Chang, T. I., Montez-Rath, M. E., Shen, J. I., Solomon, M. D., Chertow, G. M., Winkelmayer, W. C. 2014; 3 (5)

    Abstract

    Coronary stenting in patients on dialysis has increased by nearly 50% over the past decade, despite heightened risks of associated stent thrombosis and bleeding relative to the general population. We examined clopidogrel, prasugrel or ticlopidine use after percutaneous coronary intervention (PCI) with stenting in patients on dialysis. We conducted 3-, 6-, and 12-month landmark analyses to test the hypothesis that thienopyridine discontinuation prior to those time points would be associated with higher risks of death, myocardial infarction, or repeat revascularization, and a lower risk of major bleeding episodes compared with continued thienopyridine use.Using the US Renal Data System, we identified 8458 patients on dialysis with Medicare Parts A+B+D undergoing PCI with stenting between July 2007 and December 2010. Ninety-nine percent of all thienopyridine prescriptions were for clopidogrel. At 3 months, 82% of patients who received drug-eluting stents (DES) had evidence of thienopyridine use. These proportions fell to 62% and 40% at 6 and 12 months, respectively. In patients who received a bare-metal stent (BMS), 70%, 34%, and 26% of patients had evidence of thienopyridine use at 3, 6, and 12 months, respectively. In patients who received a DES, there was a suggestion of higher risks of death or myocardial infarction associated with thienopyridine discontinuation in the 3-, 6-, and 12-months landmark analyses, but no higher risk of major bleeding episodes. In patients who received a BMS, there were no differences in death or cardiovascular events, and possibly lower risk of major bleeding with thienopyridine discontinuation in the 3- and 6-month landmark analyses.The majority of patients on dialysis who undergo PCI discontinue thienopyridines before 1 year regardless of stent type. While not definitive, these data suggest that longer-term thienopyridine use may be of benefit to patients on dialysis who undergo PCI with DES.

    View details for DOI 10.1161/JAHA.114.001356

    View details for PubMedID 25336465

  • Thienopyridine use after coronary stenting in low income patients enrolled in medicare part D receiving maintenance dialysis. Journal of the American Heart Association Chang, T. I., Montez-Rath, M. E., Shen, J. I., Solomon, M. D., Chertow, G. M., Winkelmayer, W. C. 2014; 3 (5)

    View details for DOI 10.1161/JAHA.114.001356

    View details for PubMedID 25336465

  • Prognostic stratification in older adults commencing dialysis. journals of gerontology. Series A, Biological sciences and medical sciences Cheung, K. L., Montez-Rath, M. E., Chertow, G. M., Winkelmayer, W. C., Periyakoil, V. S., Kurella Tamura, M. 2014; 69 (8): 1033-1039

    Abstract

    Accurate prognostic models could inform treatment decisions for older adults with end-stage renal disease who are considering dialysis and might identify patients more appropriate for conservative care or hospice.In a cohort of patients aged ?67 years commencing dialysis in the United States between January 1, 2008 and June 30, 2009, we compared the discrimination of three existing instruments (the Liu index; the French Renal Epidemiology and Information Network score; and hospice eligibility criteria) for the prediction of 6-month mortality. We estimated the odds of death associated with each prognostic index using logistic regression with and without adjustment for age. Predictive indices were compared using the concordance ("c")-statistic.Of 44,109 eligible patients, 10,289 (23.3%) died within 6 months of dialysis initiation. The c-statistic for the Liu, Renal Epidemiology and Information Network, hospice eligibility criteria, and combined Liu/hospice eligibility criteria scores without and with age were 0.62/0.65, 0.63/0.66, 0.65/0.68, and 0.68/0.70, respectively. Discrimination was poorer at older ages, especially for the Liu and Renal Epidemiology and Information Network scores. Although sensitivity was poor, a Renal Epidemiology and Information Network score ?9 or an hospice eligibility criteria ?3 had relatively high specificity.Existing prognostic indices based on administrative data perform poorly with respect to prediction of 6-month mortality in older patients with end-stage renal disease commencing dialysis.

    View details for DOI 10.1093/gerona/glt289

    View details for PubMedID 24482541

  • Addressing Missing Data in Clinical Studies of Kidney Diseases CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Montez-Rath, M. E., Winkelmayer, W. C., Desai, M. 2014; 9 (7): 1328-1335

    Abstract

    Missing data constitute a problem present in all studies of medical research. The most common approach to handling missing data-complete case analysis-relies on assumptions about missing data that rarely hold in practice. The implications of this approach are biased and inefficient descriptions of relationships of interest. Here, various approaches for handling missing data in clinical studies are described. In particular, this work promotes the use of multiple imputation methods that rely on assumptions about missingness that are more flexible than those assumptions relied on by the most common method in use. Furthermore, multiple imputation methods are becoming increasingly more accessible in mainstream statistical software packages, making them both a sound and practical choice. The use of multiple imputation methods is illustrated with examples pertinent to kidney research, and concrete guidance on their use is provided.

    View details for DOI 10.2215/CJN.10141013

    View details for Web of Science ID 000338615300024

  • Correlates and variance decomposition analysis of heparin dosing for maintenance hemodialysis in older US patients. Pharmacoepidemiology and drug safety Shen, J. I., Montez-Rath, M. E., Mitani, A. A., Erickson, K. F., Winkelmayer, W. C. 2014; 23 (5): 515-525

    Abstract

    Heparin is commonly used to anticoagulate the hemodialysis (HD) circuit. Despite the bleeding risk, no American standards exist for its administration. We identified correlates and quantified sources of variance in heparin dosing for HD.We performed a cross-sectional study of patients aged 67?years or older who underwent HD with heparin on one of two randomly chosen days in 2008 at a national chain of dialysis facilities. Using a mixed effects model with random intercept for facility and fixed patient and facility characteristics, we examined heparin dosing at patient and facility levels.The median heparin dose among the 17?722 patients treated in 1366 facilities was 4000 (25th-75th percentile: 2625-6000) units. In multivariable-adjusted analyses, higher weight, longer session duration, catheter use, and dialyzer reuse were significantly associated with higher heparin dose. Dose also varied considerably among census divisions. Of the overall variance in dose, 21% was due to between-facility differences, independent of facilities' case mix, geography, size, or rurality; 79% was due to differences at the patient level. The patient and facility characteristics in our model explained only 25% of the variance at the patient level.Despite the lack of standards for heparin administration, we noted patterns of use, including weight-based and time-dependent dosing. Most of the variance was at the patient level; however, only a quarter of it could be explained. The high amount of unexplained variance suggests that factors other than clinical need are driving heparin dosing and that there is likely room for more judicious dosing of heparin. Copyright © 2014 John Wiley & Sons, Ltd.

    View details for DOI 10.1002/pds.3595

    View details for PubMedID 24677688

  • Temporal trends in the incidence, treatment and outcomes of hip fracture after first kidney transplantation in the United States. American journal of transplantation Sukumaran Nair, S., Lenihan, C. R., Montez-Rath, M. E., Lowenberg, D. W., Chertow, G. M., Winkelmayer, W. C. 2014; 14 (4): 943-951

    Abstract

    It is currently unknown whether any secular trends exist in the incidence and outcomes of hip fracture in kidney transplant recipients (KTR). We identified first-time KTR (1997-2010) who had >1 year of Medicare coverage and no recorded history of hip fracture. New hip fractures were identified from corresponding diagnosis and surgical procedure codes. Outcomes studied included time to hip fracture, type of surgery received and 30-day mortality. Of 69?740 KTR transplanted in 1997-2010, 597 experienced a hip fracture event during 155?341 person-years of follow-up for an incidence rate of 3.8 per 1000 person-years. While unadjusted hip fracture incidence did not change, strong confounding by case mix was present. Using year of transplantation as a continuous variable, the hazard ratio (HR) for hip fracture in 2010 compared with 1997, adjusted for demographic, dialysis, comorbid and most transplant-related factors, was 0.56 (95% confidence interval [CI]: 0.41-0.77). Adjusting for baseline immunosuppression modestly attenuated the HR (0.68; 95% CI: 0.47-0.99). The 30-day mortality was 2.2 (95% CI: 1.3-3.7) per 100 events. In summary, hip fractures remain an important complication after kidney transplantation. Since 1997, case-mix adjusted posttransplant hip fracture rates have declined substantially. Changes in immunosuppressive therapy appear to be partly responsible for these favorable findings.

    View details for DOI 10.1111/ajt.12652

    View details for PubMedID 24712332

  • Multivessel coronary revascularization and outcomes in kidney transplant recipients. Transplant international Lenihan, C. R., Montez-Rath, M. E., Winkelmayer, W. C., Chang, T. I. 2013; 26 (11): 1080-1087

    Abstract

    Coronary artery disease is a major cause of morbidity and mortality in the kidney transplant population. We compared the long-term outcomes of coronary artery bypass graft (CABG) surgery with percutaneous coronary intervention (PCI) for multivessel coronary disease in a contemporary cohort of US kidney transplant recipients. From the U.S. Renal Data System, we identified all adult kidney transplant patients with ?6 months of Medicare A+B undergoing first recorded multivessel coronary revascularization from 1997 to 2009. The associations of CABG versus PCI with death and the composite of death or myocardial infarction (MI) were compared using proportional hazards regression. Of the 2272 patients included in the study, 1594 underwent CABG and 678 underwent PCI. The estimated 5-year survival rate was 55% [95% confidence interval (CI) 53% to 57%] following coronary revascularization, with no significant association between revascularization type and death [adjusted hazard ratio (aHR) = 1.08; CI 0.94-1.23] or the composite of death or MI (aHR = 1.07; CI 0.96-1.18). Separate propensity score-matched analyses yielded similar results. In this analysis of kidney transplant recipients undergoing multivessel coronary revascularization, we found no difference between CABG and PCI in terms of survival or the composite of death and MI.

    View details for DOI 10.1111/tri.12168

    View details for PubMedID 23957580

  • Outcomes after kidney transplantation of patients previously diagnosed with atrial fibrillation. American journal of transplantation Lenihan, C. R., Montez-Rath, M. E., Scandling, J. D., Turakhia, M. P., Winkelmayer, W. C. 2013; 13 (6): 1566-1575

    Abstract

    Little is known about the prevalence and outcomes of patients with atrial fibrillation/flutter (AF) who receive a kidney transplant. We identified all patients who had >1 year of uninterrupted Medicare A+B coverage before receiving their first kidney transplant (1997-2009). The presence of pretransplant AF was ascertained from diagnosis codes in Medicare physician claims. We studied the posttransplant outcomes of death, all-cause graft failure, death-censored graft failure and stroke using multivariable Cox regression. Of 62 706 eligible first kidney transplant recipients studied, 3794 (6.4%) were diagnosed with AF prior to kidney transplant. Over a mean follow up of 4.9 years, 40.6% of AF patients and 24.9% without AF died. All-cause and death-censored graft failure were 46.8% and 16.5%, respectively, in the AF group and 36.4% and 19.5%, respectively, in those without AF. Ischemic stroke occurred in 2.8% of patients with and 1.6% of patients without AF. In patients with AF, multivariable-adjusted hazard ratios (95% confidence intervals) for death, graft failure, death-censored graft failure and ischemic stroke were 1.46 (1.38-1.54), 1.41 (1.34-1.48), 1.26 (1.15-1.37) and 1.36 (1.10-1.68), respectively. Pre-existing AF is associated with poor posttransplant outcomes. Special attention should be paid to AF in pretransplant evaluation, counseling and risk stratification of kidney transplant candidates.

    View details for DOI 10.1111/ajt.12197

    View details for PubMedID 23721555

  • Trends in the incidence of intestinal perforation in US dialysis patients (1992-2005). Journal of nephrology Yang, J., Lee, T., Montez-Rath, M. E., Desai, M., Winkelmayer, W. C. 2013; 26 (2): 281-288

    Abstract

    Little is known about the incidence of intestinal perforation in patients undergoing dialysis. Concerns exist that sevelamer hydrochloride may increase the risk of intestinal perforation. We examined long-term trends for the incidence of intestinal perforation among US dialysis patients.We studied all dialysis patients (1992-2005) who had Medicare as primary payer. We used ICD-9 diagnosis code 569.83 to ascertain events of intestinal perforation. We studied (a) all perforations and (b) perforations that did not appear to be associated with specific causative conditions (specific diseases or iatrogenic procedures within 7 days of perforation). We used Poisson regression to model the annual number of intestinal perforations and tested for any changes in levels and temporal trends of incidence rates before versus after January 1, 1999.Overall, 1,060,132 patients contributed 2.7 million patient-years. We observed 12,355 events of intestinal perforation and 7,814 spontaneous perforations. The corresponding incidence rates were 4.6 (total) and 2.9 (spontaneous perforation) episodes per 1,000 person-years, respectively. For both outcome definitions, 30-day mortality was 42%. Unadjusted and adjusted incidence rates were not materially different over time. Formal tests for any changes in the level or slope of incidence comparing time periods before and after January 1, 1999, indicated no evidence for any changes in the incidence of intestinal perforation over time.In US dialysis patients, incidence of intestinal perforation was low, but associated with high short-term mortality. We did not detect any significant changes in the incidence of intestinal perforation before versus after approval of sevelamer hydrochloride in late 1998.

    View details for DOI 10.5301/jn.5000104

    View details for PubMedID 22419235

  • Trends in acute kidney injury, associated use of dialysis, and mortality after cardiac surgery, 1999 to 2008. Annals of thoracic surgery Lenihan, C. R., Montez-Rath, M. E., Mora Mangano, C. T., Chertow, G. M., Winkelmayer, W. C. 2013; 95 (1): 20-28

    Abstract

    The development of acute kidney injury (AKI) after cardiac surgery is associated with significant mortality, morbidity, and cost. The last decade has seen major changes in the complexity of cardiac surgical candidates and in the number and type of cardiac surgical procedures being performed.Using data from the Nationwide Inpatient Sample, we determined the annual rates of AKI, AKI requiring dialysis (AKI-D), and inpatient mortality after cardiac surgery in the United States in the years 1999 through 2008.Inpatient mortality with AKI and AKI-D decreased from 27.9% and 45.9%, respectively, in 1999 to 12.8% and 35.3%, respectively, in 2008. Compared with 1999, the odds of AKI and AKI-D in 2008, adjusted for demographic and clinical factors, were 3.30 (95% confidence interval [CI]: 2.89 to 3.77) and 2.23 (95% CI: 1.78 to 2.80), respectively. Corresponding adjusted odds of death associated with AKI and AKI-D were 0.31 (95% CI: 0.26 to 0.36) and 0.47 (95% CI: 0.34 to 0.65.) Taken together, the attributable risks for death after cardiac surgery associated with AKI and AKI-D increased from 30% and 5%, respectively, in 1999 to 47% and 14%, respectively, in 2008.In sum, despite improvements in individual patient outcomes over the decade 1999 to 2008, the population contribution of AKI and AKI-D to inpatient mortality after surgery increased over the same period.

    View details for DOI 10.1016/j.athoracsur.2012.05.131

    View details for PubMedID 23272825

  • Trends in Acute Kidney Injury, Associated Use of Dialysis, and Mortality After Cardiac Surgery, 1999 to 2008 ANNALS OF THORACIC SURGERY Lenihan, C. R., Montez-Rath, M. E., Mangano, C. T., Chertow, G. M., Winkelmayer, W. C. 2013; 95 (1): 20-28
  • Risk factors of short-term mortality after acute nonvariceal upper gastrointestinal bleeding in patients on dialysis: a population-based study. BMC nephrology Yang, J., Lee, T., Montez-Rath, M. E., Chertow, G. M., Winkelmayer, W. C. 2013; 14: 97-?

    View details for DOI 10.1186/1471-2369-14-97

    View details for PubMedID 23621917

  • Risk factors of short-term mortality after acute nonvariceal upper gastrointestinal bleeding in patients on dialysis: a population-based study. BMC nephrology Yang, J., Lee, T., Montez-Rath, M. E., Chertow, G. M., Winkelmayer, W. C. 2013; 14: 97-?

    Abstract

    Impaired kidney function is an established predictor of mortality after acute nonvariceal upper gastrointestinal bleeding (ANVUGIB); however, which factors are associated with mortality after ANVUGIB among patients undergoing dialysis is unknown. We examined the associations among demographic characteristics, dialysis-specific features, and comorbid conditions with short-term mortality after ANVUGIB among patients on dialysis.Design: Retrospective cohort study. Setting: United States Renal Data System (USRDS), a nation-wide registry of patients with end-stage renal disease. Participants: All ANVUGIB episodes identified by validated algorithms in Medicare-covered patients between 2003 and 2007. Measurements: Demographic characteristics and comorbid conditions from 1 year of billing claims prior to each bleeding event. We used logistic regression extended with generalized estimating equations methods to model the associations among risk factors and 30-day mortality following ANVUGIB events.From 2003 to 2007, we identified 40,016 eligible patients with 50,497 episodes of ANVUGIB. Overall 30-day mortality was 10.7% (95% CI: 10.4-11.0). Older age, white race, longer dialysis vintage, peritoneal dialysis (vs. hemodialysis), and hospitalized (vs. outpatient) episodes were independently associated with a higher risk of 30-day mortality. Most but not all comorbid conditions were associated with death after ANVUGIB. The joint ability of all factors captured to discriminate mortality was modest (c=0.68).We identified a profile of risk factors for 30-day mortality after ANVUGIB among patients on dialysis that was distinct from what had been reported in non-dialysis populations. Specifically, peritoneal dialysis and more years since initiation of dialysis were independently associated with short-term death after ANVUGIB.

    View details for DOI 10.1186/1471-2369-14-97

    View details for PubMedID 23621917

  • Multivessel Coronary Artery Bypass Grafting Versus Percutaneous Coronary Intervention in ESRD JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Chang, T. I., Shilane, D., Kazi, D. S., Montez-Rath, M. E., Hlatky, M. A., Winkelmayer, W. C. 2012; 23 (12): 2042-2049

    Abstract

    Thirty to sixty percent of patients with ESRD on dialysis have coronary heart disease, but the optimal strategy for coronary revascularization is unknown. We used data from the United States Renal Data System to define a cohort of 21,981 patients on maintenance dialysis who received initial coronary revascularization with either coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) between 1997 and 2009 and had at least 6 months of prior Medicare coverage as their primary payer. The primary outcome was death from any cause, and the secondary outcome was a composite of death or myocardial infarction. Overall survival rates were consistently poor during the study period, with unadjusted 5-year survival rates of 22%-25% irrespective of revascularization strategy. Using multivariable-adjusted proportional hazards regression, we found that CABG compared with PCI associated with significantly lower risks for both death (HR=0.87, 95% CI=0.84-0.90) and the composite of death or myocardial infarction (HR=0.88, 95% CI=0.86-0.91). Results were similar in analyses using a propensity score-matched cohort. In the absence of data from randomized trials, these results suggest that CABG may be preferred over PCI for multivessel coronary revascularization in appropriately selected patients on maintenance dialysis.

    View details for DOI 10.1681/ASN.2012060554

    View details for Web of Science ID 000311819000017

    View details for PubMedID 23204445

  • Trends in Acute Nonvariceal Upper Gastrointestinal Bleeding in Dialysis Patients JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Yang, J., Lee, T., Montez-Rath, M. E., Paik, J., Chertow, G. M., Desai, M., Winkelmayer, W. C. 2012; 23 (3): 495-506

    Abstract

    Impaired kidney function is a risk factor for upper gastrointestinal (GI) bleeding, an event associated with poor outcomes. The burden of upper GI bleeding and its effect on patients with ESRD are not well described. Using data from the US Renal Data System, we quantified the rates of occurrence of and associated 30-day mortality from acute, nonvariceal upper GI bleeding in patients undergoing dialysis; we used medical claims and previously validated algorithms where available. Overall, 948,345 patients contributed 2,296,323 patient-years for study. The occurrence rates for upper GI bleeding were 57 and 328 episodes per 1000 person-years according to stringent and lenient definitions of acute, nonvariceal upper GI bleeding, respectively. Unadjusted occurrence rates remained flat (stringent) or increased (lenient) from 1997 to 2008; after adjustment for sociodemographic characteristics and comorbid conditions, however, we found a significant decline for both definitions (linear approximation, 2.7% and 1.5% per year, respectively; P<0.001). In more recent years, patients had higher hematocrit levels before upper GI bleeding episodes and were more likely to receive blood transfusions during an episode. Overall 30-day mortality was 11.8%, which declined significantly over time (relative declines of 2.3% or 2.8% per year for the stringent and lenient definitions, respectively). In summary, despite declining trends worldwide, crude rates of acute, nonvariceal upper GI bleeding among patients undergoing dialysis have not decreased in the past 10 years. Although 30-day mortality related to upper GI bleeding declined, perhaps reflecting improvements in medical care, the burden on the ESRD population remains substantial.

    View details for DOI 10.1681/ASN.2011070658

    View details for Web of Science ID 000301206900017

    View details for PubMedID 22266666

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