I am interested in using statistical methods to understand and improve human health. I currently collaborate with investigators in the medical school in chronic disease prevention, pediatrics, and nutrition. I joined the Stanford Quantitative Sciences Unit in 2015 after completing my PhD in Biostatistics at the University of North Carolina at Chapel Hill. I am also interested in software development. At UNC, I wrote the R packages RI2by2 and interferenceCI to accompany papers from my dissertation, titled "Causal inference for binary data with interference". At Stanford, I helped translate the near-far matching method into an R package titled nearfar.

Education & Certifications

  • PhD, University of North Carolina, Chapel Hill, Biostatistics (2015)


All Publications

  • Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion The DIETFITS Randomized Clinical Trial JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Gardner, C. D., Trepanowski, J. F., Del Gobbo, L. C., Hauser, M. E., Rigdon, J., Ioannidis, J. A., Desai, M., King, A. C. 2018; 319 (7): 667–79


    Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets.To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss.The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss.Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality.Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss.Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was -5.3 kg for the HLF diet vs -6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, -0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups.In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for Identifier: NCT01826591.

    View details for DOI 10.1001/jama.2018.0245

    View details for Web of Science ID 000425508400017

    View details for PubMedID 29466592

    View details for PubMedCentralID PMC5839290

  • Antioxidants from diet or supplements do not alter inflammatory markers in adults with cardiovascular disease risk. A pilot randomized controlled trial NUTRITION RESEARCH Dewell, A., Tsao, P., Rigdon, J., Gardner, C. D. 2018; 50: 63–72


    Antioxidants have been reported to have anti-inflammatory effects, but there is a lack of research comparing food to supplement antioxidant sources. The aim of this study was to determine if increases in intake of foods naturally rich in antioxidants would lower blood levels of inflammatory markers more than consuming antioxidant supplements among adults with cardiovascular disease risk factors. Eighty-eight generally healthy adults with ≥1 elevated risk factor for cardiovascular disease were randomized in a single-blind (diets)/double-blind (supplements), parallel-group study for 8 weeks. Participants consumed (1) usual diet and placebo pills (n = 29), (2) usual diet and antioxidant supplements (n = 29), or (3) antioxidant-rich foods closely matched to antioxidant content of supplements and placebo (n = 30). Usual diet combined with antioxidant supplements or increased antioxidant-rich food intake was designed to approximately double daily habitual antioxidant intake. Antioxidant pills included carotenoids, mixed tocopherols, vitamin C, and selenium. Fasting blood samples were analyzed for inflammatory marker concentrations of interleukin-6, monocyte chemotactic protein-1, and soluble intercellular adhesion molecule-1. Participants in the intervention groups successfully doubled most antioxidants as verified by diet records and elevated blood concentrations in treatment groups. Baseline levels of inflammatory markers for the entire study group were 110 ± 65 pg/mL for monocyte chemotactic protein-1, 0.9 ± 0.7 pg/mL for interleukin-6, and 217 ± 56 ng/mL for soluble intercellular adhesion molecule-1 (means ± standard deviation) and did not differ by treatment arm. After 8 weeks, there were no significant within-group changes or between-group 8-week change differences in inflammatory marker concentrations. In conclusion, no beneficial effects were detected on the inflammatory markers investigated in response to antioxidants from foods or supplements.

    View details for DOI 10.1016/j.nutres.2017.10.017

    View details for Web of Science ID 000428942800007

    View details for PubMedID 29540273

    View details for PubMedCentralID PMC5858717

  • Inhibition of Multiple Nodes in the PI3K/Akt/mTOR Pathway Synergistically Suppresses Post-Transplant B Cell Lymphomas Sang, A., McPherson, M., Ivison, G., Qu, X., Rigdon, J., Esquivel, C., Krams, S., Martinez, O. WILEY. 2018: 20
  • Higher Absolute Lymphocyte Counts Predict Lower Mortality from Early-Stage Triple-Negative Breast Cancer. Clinical cancer research : an official journal of the American Association for Cancer Research Afghahi, A., Purington, N., Han, S. S., Desai, M., Pierson, E., Mathur, M. B., Seto, T., Thompson, C. A., Rigdon, J., Telli, M. L., Badve, S. S., Curtis, C., West, R. B., Horst, K., Gomez, S. L., Ford, J. M., Sledge, G. W., Kurian, A. W. 2018


    Tumor-infiltrating lymphocytes (TILs) in pre-treatment biopsies are associated with improved survival in triple-negative breast cancer (TNBC). We investigated whether higher peripheral lymphocyte counts are associated with lower breast cancer-specific mortality (BCM) and overall mortality (OM) in TNBC.Data on treatments and diagnostic tests from electronic medical records of two healthcare systems were linked with demographic, clinical, pathologic, and mortality data from the California Cancer Registry. Multivariable regression models adjusted for age, race/ethnicity, socioeconomic status, cancer stage, grade, neoadjuvant/adjuvant chemotherapy use, radiotherapy use, and germline BRCA1/2 mutations were used to evaluate associations between absolute lymphocyte count (ALC), BCM and OM. For a subgroup with TILs data available, we explored the relationship between TILs and peripheral lymphocyte counts.1,463 Stage I-III TNBC patients were diagnosed from 2000-2014; 1113 (76%) received neoadjuvant/adjuvant chemotherapy within one year of diagnosis. Of 759 patients with available ALC data, 481 (63.4%) were ever lymphopenic (minimum ALC <1.0 K/μL). On multivariable analysis, higher minimum ALC, but not absolute neutrophil count, predicted lower OM (hazard ratio [HR]: 0.23, 95% confidence interval [CI]: 0.16-0.35) and BCM (HR: 0.19, CI: 0.11-0.34). Five-year probability of BCM was 15% for patients who were ever lymphopenic versus 4% for those who were not. An exploratory analysis (N=70) showed a significant association between TILs and higher peripheral lymphocyte counts during neoadjuvant chemotherapy.Higher peripheral lymphocyte counts predicted lower mortality from early-stage, potentially curable TNBC, suggesting that immune function may enhance the effectiveness of early TNBC treatment.

    View details for DOI 10.1158/1078-0432.CCR-17-1323

    View details for PubMedID 29581131

  • Supplemental Nutrition Assistance Program (SNAP) Participation and Health Care Expenditures Among Low-Income Adults JAMA INTERNAL MEDICINE Berkowitz, S. A., Seligman, H. K., Rigdon, J., Meigs, J. B., Basu, S. 2017; 177 (11): 1642–49


    Food insecurity is associated with high health care expenditures, but the effectiveness of food insecurity interventions on health care costs is unknown.To determine whether the Supplemental Nutrition Assistance Program (SNAP), which addresses food insecurity, can reduce health care expenditures.This is a retrospective cohort study of 4447 noninstitutionalized adults with income below 200% of the federal poverty threshold who participated in the 2011 National Health Interview Survey (NHIS) and the 2012-2013 Medical Expenditure Panel Survey (MEPS).Self-reported SNAP participation in 2011.Total health care expenditures (all paid claims and out-of-pocket costs) in the 2012-2013 period. To test whether SNAP participation was associated with lower subsequent health care expenditures, we used generalized linear modeling (gamma distribution, log link, with survey design information), adjusting for demographics (age, gender, race/ethnicity), socioeconomic factors (income, education, Social Security Disability Insurance disability, urban/rural), census region, health insurance, and self-reported medical conditions. We also conducted sensitivity analyses as a robustness check for these modeling assumptions.A total of 4447 participants (2567 women and 1880 men) were enrolled in the study, mean (SE) age, 42.7 (0.5) years; 1889 were SNAP participants, and 2558 were not. Compared with other low-income adults, SNAP participants were younger (mean [SE] age, 40.3 [0.6] vs 44.1 [0.7] years), more likely to have public insurance or be uninsured (84.9% vs 67.7%), and more likely to be disabled (24.2% vs 10.6%) (P < .001 for all). In age- and gender-adjusted models, health care expenditures between those who did and did not participate in SNAP were similar (difference, $34; 95% CI, -$1097 to $1165). In fully adjusted models, SNAP was associated with lower estimated annual health care expenditures (-$1409; 95% CI, -$2694 to -$125). Sensitivity analyses were consistent with these results, also indicating that SNAP participation was associated with significantly lower estimated expenditures.SNAP enrollment is associated with reduced health care spending among low-income American adults, a finding consistent across several analytic approaches. Encouraging SNAP enrollment among eligible adults may help reduce health care costs in the United States.

    View details for DOI 10.1001/jamainternmed.2017.4841

    View details for Web of Science ID 000414525700022

    View details for PubMedID 28973507

    View details for PubMedCentralID PMC5710268

  • Benefit and harm of intensive blood pressure treatment: Derivation and validation of risk models using data from the SPRINT and ACCORD trials PLOS MEDICINE Basu, S., Sussman, J. B., Rigdon, J., Steimle, L., Denton, B. T., Hayward, R. A. 2017; 14 (10): e1002410


    Intensive blood pressure (BP) treatment can avert cardiovascular disease (CVD) events but can cause some serious adverse events. We sought to develop and validate risk models for predicting absolute risk difference (increased risk or decreased risk) for CVD events and serious adverse events from intensive BP therapy. A secondary aim was to test if the statistical method of elastic net regularization would improve the estimation of risk models for predicting absolute risk difference, as compared to a traditional backwards variable selection approach.Cox models were derived from SPRINT trial data and validated on ACCORD-BP trial data to estimate risk of CVD events and serious adverse events; the models included terms for intensive BP treatment and heterogeneous response to intensive treatment. The Cox models were then used to estimate the absolute reduction in probability of CVD events (benefit) and absolute increase in probability of serious adverse events (harm) for each individual from intensive treatment. We compared the method of elastic net regularization, which uses repeated internal cross-validation to select variables and estimate coefficients in the presence of collinearity, to a traditional backwards variable selection approach. Data from 9,069 SPRINT participants with complete data on covariates were utilized for model development, and data from 4,498 ACCORD-BP participants with complete data were utilized for model validation. Participants were exposed to intensive (goal systolic pressure < 120 mm Hg) versus standard (<140 mm Hg) treatment. Two composite primary outcome measures were evaluated: (i) CVD events/deaths (myocardial infarction, acute coronary syndrome, stroke, congestive heart failure, or CVD death), and (ii) serious adverse events (hypotension, syncope, electrolyte abnormalities, bradycardia, or acute kidney injury/failure). The model for CVD chosen through elastic net regularization included interaction terms suggesting that older age, black race, higher diastolic BP, and higher lipids were associated with greater CVD risk reduction benefits from intensive treatment, while current smoking was associated with fewer benefits. The model for serious adverse events chosen through elastic net regularization suggested that male sex, current smoking, statin use, elevated creatinine, and higher lipids were associated with greater risk of serious adverse events from intensive treatment. SPRINT participants in the highest predicted benefit subgroup had a number needed to treat (NNT) of 24 to prevent 1 CVD event/death over 5 years (absolute risk reduction [ARR] = 0.042, 95% CI: 0.018, 0.066; P = 0.001), those in the middle predicted benefit subgroup had a NNT of 76 (ARR = 0.013, 95% CI: -0.0001, 0.026; P = 0.053), and those in the lowest subgroup had no significant risk reduction (ARR = 0.006, 95% CI: -0.007, 0.018; P = 0.71). Those in the highest predicted harm subgroup had a number needed to harm (NNH) of 27 to induce 1 serious adverse event (absolute risk increase [ARI] = 0.038, 95% CI: 0.014, 0.061; P = 0.002), those in the middle predicted harm subgroup had a NNH of 41 (ARI = 0.025, 95% CI: 0.012, 0.038; P < 0.001), and those in the lowest subgroup had no significant risk increase (ARI = -0.007, 95% CI: -0.043, 0.030; P = 0.72). In ACCORD-BP, participants in the highest subgroup of predicted benefit had significant absolute CVD risk reduction, but the overall ACCORD-BP participant sample was skewed towards participants with less predicted benefit and more predicted risk than in SPRINT. The models chosen through traditional backwards selection had similar ability to identify absolute risk difference for CVD as the elastic net models, but poorer ability to correctly identify absolute risk difference for serious adverse events. A key limitation of the analysis is the limited sample size of the ACCORD-BP trial, which expanded confidence intervals for ARI among persons with type 2 diabetes. Additionally, it is not possible to mechanistically explain the physiological relationships explaining the heterogeneous treatment effects captured by the models, since the study was an observational secondary data analysis.We found that predictive models could help identify subgroups of participants in both SPRINT and ACCORD-BP who had lower versus higher ARRs in CVD events/deaths with intensive BP treatment, and participants who had lower versus higher ARIs in serious adverse events.

    View details for DOI 10.1371/journal.pmed.1002410

    View details for Web of Science ID 000414064100014

    View details for PubMedID 29040268

    View details for PubMedCentralID PMC5644999

  • Network analysis: a novel method for mapping neonatal acute transport patterns in California. Journal of perinatology Kunz, S. N., Zupancic, J. A., Rigdon, J., Phibbs, C. S., Lee, H. C., Gould, J. B., Leskovec, J., Profit, J. 2017; 37 (6): 702-708


    The objectives of this study are to use network analysis to describe the pattern of neonatal transfers in California, to compare empirical sub-networks with established referral regions and to determine factors associated with transport outside the originating sub-network.This cross-sectional database study included 6546 infants <28 days old transported within California in 2012. After generating a graph representing acute transfers between hospitals (n=6696), we used community detection techniques to identify more tightly connected sub-networks. These empirically derived sub-networks were compared with state-defined regional referral networks. Reasons for transfer between empirical sub-networks were assessed using logistic regression.Empirical sub-networks showed significant overlap with regulatory regions (P<0.001). Transfer outside the empirical sub-network was associated with major congenital anomalies (P<0.001), need for surgery (P=0.01) and insurance as the reason for transfer (P<0.001).Network analysis accurately reflected empirical neonatal transfer patterns, potentially facilitating quantitative, rather than qualitative, analysis of regionalized health care delivery systems.Journal of Perinatology advance online publication, 23 March 2017; doi:10.1038/jp.2017.20.

    View details for DOI 10.1038/jp.2017.20

    View details for PubMedID 28333155

  • Factors Associated With Provider Burnout in the NICU PEDIATRICS Tawfik, D. S., Phibbs, C. S., Sexton, J. B., Kan, P., Sharek, P. J., Nisbet, C. C., Rigdon, J., Trockel, M., Profit, J. 2017; 139 (5)


    NICUs vary greatly in patient acuity and volume and represent a wide array of organizational structures, but the effect of these differences on NICU providers is unknown. This study sought to test the relation between provider burnout prevalence and organizational factors in California NICUs.Provider perceptions of burnout were obtained from 1934 nurse practitioners, physicians, registered nurses, and respiratory therapists in 41 California NICUs via a validated 4-item questionnaire based on the Maslach Burnout Inventory. The relations between burnout and organizational factors of each NICU were evaluated via t-test comparison of quartiles, univariable regression, and multivariable regression.Overall burnout prevalence was 26.7% ± 9.8%. Highest burnout prevalence was found among NICUs with higher average daily admissions (32.1% ± 6.4% vs 17.2% ± 6.7%, P < .001), higher average occupancy (28.1% ± 8.1% vs 19.9% ± 8.4%, P = .02), and those with electronic health records (28% ± 11% vs 18% ± 7%, P = .03). In sensitivity analysis, nursing burnout was more sensitive to organizational differences than physician burnout in multivariable modeling, significantly associated with average daily admissions, late transfer proportion, nursing hours per patient day, and mortality per 1000 infants. Burnout prevalence showed no association with proportion of high-risk patients, teaching hospital distinction, or in-house attending presence.Burnout is most prevalent in NICUs with high patient volume and electronic health records and may affect nurses disproportionately. Interventions to reduce burnout prevalence may be of greater importance in NICUs with ≥10 weekly admissions.

    View details for DOI 10.1542/peds.2016-4134

    View details for Web of Science ID 000400371500040

    View details for PubMedID 28557756

  • Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA internal medicine Trepanowski, J. F., Kroeger, C. M., Barnosky, A., Klempel, M. C., Bhutani, S., Hoddy, K. K., Gabel, K., Freels, S., Rigdon, J., Rood, J., Ravussin, E., Varady, K. A. 2017


    Alternate-day fasting has become increasingly popular, yet, to date, no long-term randomized clinical trials have evaluated its efficacy.To compare the effects of alternate-day fasting vs daily calorie restriction on weight loss, weight maintenance, and risk indicators for cardiovascular disease.A single-center randomized clinical trial of obese adults (18 to 64 years of age; mean body mass index, 34) was conducted between October 1, 2011, and January 15, 2015, at an academic institution in Chicago, Illinois.Participants were randomized to 1 of 3 groups for 1 year: alternate-day fasting (25% of energy needs on fast days; 125% of energy needs on alternating "feast days"), calorie restriction (75% of energy needs every day), or a no-intervention control. The trial involved a 6-month weight-loss phase followed by a 6-month weight-maintenance phase.The primary outcome was change in body weight. Secondary outcomes were adherence to the dietary intervention and risk indicators for cardiovascular disease.Among the 100 participants (86 women and 14 men; mean [SD] age, 44 [11] years), the dropout rate was highest in the alternate-day fasting group (13 of 34 [38%]), vs the daily calorie restriction group (10 of 35 [29%]) and control group (8 of 31 [26%]). Mean weight loss was similar for participants in the alternate-day fasting group and those in the daily calorie restriction group at month 6 (-6.8% [95% CI, -9.1% to -4.5%] vs -6.8% [95% CI, -9.1% to -4.6%]) and month 12 (-6.0% [95% CI, -8.5% to -3.6%] vs -5.3% [95% CI, -7.6% to -3.0%]) relative to those in the control group. Participants in the alternate-day fasting group ate more than prescribed on fast days, and less than prescribed on feast days, while those in the daily calorie restriction group generally met their prescribed energy goals. There were no significant differences between the intervention groups in blood pressure, heart rate, triglycerides, fasting glucose, fasting insulin, insulin resistance, C-reactive protein, or homocysteine concentrations at month 6 or 12. Mean high-density lipoprotein cholesterol levels at month 6 significantly increased among the participants in the alternate-day fasting group (6.2 mg/dL [95% CI, 0.1-12.4 mg/dL]), but not at month 12 (1.0 mg/dL [95% CI, -5.9 to 7.8 mg/dL]), relative to those in the daily calorie restriction group. Mean low-density lipoprotein cholesterol levels were significantly elevated by month 12 among the participants in the alternate-day fasting group (11.5 mg/dL [95% CI, 1.9-21.1 mg/dL]) compared with those in the daily calorie restriction group.Alternate-day fasting did not produce superior adherence, weight loss, weight maintenance, or cardioprotection vs daily calorie Identifier: NCT00960505.

    View details for DOI 10.1001/jamainternmed.2017.0936

    View details for PubMedID 28459931

  • Teamwork in the NICU Setting and Its Association with Health Care-Associated Infections in Very Low-Birth-Weight Infants. American journal of perinatology Profit, J., Sharek, P. J., Kan, P., Rigdon, J., Desai, M., Nisbet, C. C., Tawfik, D. S., Thomas, E. J., Lee, H. C., Sexton, J. B. 2017


    Background and Objective Teamwork may affect clinical care in the neonatal intensive care unit (NICU) setting. The objective of this study was to assess teamwork climate across NICUs and to test scale-level and item-level associations with health care-associated infection (HAI) rates in very low-birth-weight (VLBW) infants. Methods Cross-sectional study of the association between HAI rates, defined as any bacterial or fungal infection during the birth hospitalization, among 6,663 VLBW infants cared for in 44 NICUs between 2010 and 2012. NICU HAI rates were correlated with teamwork climate ratings obtained in 2011 from 2,073 of 3,294 eligible NICU health professionals (response rate 63%). The relation between HAI rates and NICU teamwork climate was assessed using logistic regression models including NICU as a random effect. Results Across NICUs, 36 to 100% (mean 66%) of respondents reported good teamwork. HAI rates were significantly and independently associated with teamwork climate (odds ratio, 0.82; 95% confidence interval, 0.73-0.92, p = 0.005), such that the odds of an infant contracting a HAI decreased by 18% with each 10% rise in NICU respondents reporting good teamwork. Conclusion Improving teamwork may be an important element in infection control efforts.

    View details for DOI 10.1055/s-0037-1601563

    View details for PubMedID 28395366

  • Burnout in the neonatal intensive care unit and its relation to healthcare-associated infections. Journal of perinatology Tawfik, D. S., Sexton, J. B., Kan, P., Sharek, P. J., Nisbet, C. C., Rigdon, J., Lee, H. C., Profit, J. 2017; 37 (3): 315-320


    To examine burnout prevalence among California neonatal intensive care units (NICUs) and to test the relation between burnout and healthcare-associated infection (HAI) rates in very low birth weight (VLBW) neonates.Retrospective observational study of provider perceptions of burnout from 2073 nurse practitioners, physicians, registered nurses and respiratory therapists, using a validated four-item questionnaire based on the Maslach Burnout Inventory. The relation between burnout and HAI rates among VLBW (<1500 g) neonates from each NICU was evaluated using multi-level logistic regression analysis with patient-level factors as fixed effects.We found variable prevalence of burnout across the NICUs surveyed (mean 25.2±10.1%). Healthcare-associated infection rates were 8.3±5.1% during the study period. Highest burnout prevalence was found among nurses, nurse practitioners and respiratory therapists (non-physicians, 28±11% vs 17±19% physicians), day shift workers (30±3% vs 25±4% night shift) and workers with 5 or more years of service (29±2% vs 16±6% in fewer than 3 years group). Overall burnout rates showed no correlation with risk-adjusted rates of HAIs (r=-0.133). Item-level analysis showed positive association between HAIs and perceptions of working too hard (odds ratio 1.15, 95% confidence interval 1.04-1.28). Sensitivity analysis of high-volume NICUs suggested a moderate correlation between burnout prevalence and HAIs (r=0.34).Burnout is most prevalent among non-physicians, daytime workers and experienced workers. Perceptions of working too hard associate with increased HAIs in this cohort of VLBW infants, but overall burnout prevalence is not predictive.Journal of Perinatology advance online publication, 17 November 2016; doi:10.1038/jp.2016.211.

    View details for DOI 10.1038/jp.2016.211

    View details for PubMedID 27853320

  • DIETFITS study (diet intervention examining the factors interacting with treatment success) - Study design and methods. Contemporary clinical trials Stanton, M. V., Robinson, J. L., Kirkpatrick, S. M., Farzinkhou, S., Avery, E. C., Rigdon, J., Offringa, L. C., Trepanowski, J. F., Hauser, M. E., Hartle, J. C., Cherin, R. J., King, A. C., Ioannidis, J. P., Desai, M., Gardner, C. D. 2017; 53: 151-161


    Numerous studies have attempted to identify successful dietary strategies for weight loss, and many have focused on Low-Fat vs. Low-Carbohydrate comparisons. Despite relatively small between-group differences in weight loss found in most previous studies, researchers have consistently observed relatively large between-subject differences in weight loss within any given diet group (e.g., ~25kg weight loss to ~5kg weight gain). The primary objective of this study was to identify predisposing individual factors at baseline that help explain differential weight loss achieved by individuals assigned to the same diet, particularly a pre-determined multi-locus genotype pattern and insulin resistance status. Secondary objectives included discovery strategies for further identifying potential genetic risk scores. Exploratory objectives included investigation of an extensive set of physiological, psychosocial, dietary, and behavioral variables as moderating and/or mediating variables and/or secondary outcomes. The target population was generally healthy, free-living adults with BMI 28-40kg/m(2) (n=600). The intervention consisted of a 12-month protocol of 22 one-hour evening instructional sessions led by registered dietitians, with ~15-20 participants/class. Key objectives of dietary instruction included focusing on maximizing the dietary quality of both Low-Fat and Low-Carbohydrate diets (i.e., Healthy Low-Fat vs. Healthy Low-Carbohydrate), and maximally differentiating the two diets from one another. Rather than seeking to determine if one dietary approach was better than the other for the general population, this study sought to examine whether greater overall weight loss success could be achieved by matching different people to different diets. Here we present the design and methods of the study.

    View details for DOI 10.1016/j.cct.2016.12.021

    View details for PubMedID 28027950

  • Use of Gene Expression Profiling and Chemotherapy in Early-Stage Breast Cancer: A Study of Linked Electronic Medical Records, Cancer Registry Data, and Genomic Data Across Two Health Care Systems. Journal of oncology practice / American Society of Clinical Oncology Afghahi, A., Mathur, M., Thompson, C. A., Mitani, A., Rigdon, J., Desai, M., Yu, P. P., de Bruin, M. A., Seto, T., Olson, C., Kenkare, P., Gomez, S. L., Das, A. K., Luft, H. S., Sledge, G. W., Sing, A. P., Kurian, A. W. 2016; 12 (6): e697-709


    The 21-gene recurrence score (RS) identifies patients with breast cancer who derive little benefit from chemotherapy; it may reduce unwarranted variability in the use of chemotherapy. We tested whether the use of RS seems to guide chemotherapy receipt across different cancer care settings.We developed a retrospective cohort of patients with breast cancer by using electronic medical record data from Stanford University (hereafter University) and Palo Alto Medical Foundation (hereafter Community) linked with demographic and staging data from the California Cancer Registry and RS results from the testing laboratory (Genomic Health Inc., Redwood City, CA). Multivariable analysis was performed to identify predictors of RS and chemotherapy use.In all, 10,125 patients with breast cancer were diagnosed in the University or Community systems from 2005 to 2011; 2,418 (23.9%) met RS guidelines criteria, of whom 15.6% received RS. RS was less often used for patients with involved lymph nodes, higher tumor grade, and age < 40 or ≥ 65 years. Among RS recipients, chemotherapy receipt was associated with a higher score (intermediate v low: odds ratio, 3.66; 95% CI, 1.94 to 6.91). A total of 293 patients (10.6%) received care in both health care systems (hereafter dual use); although receipt of RS was associated with dual use (v University: odds ratio, 1.73; 95% CI, 1.18 to 2.55), there was no difference in use of chemotherapy after RS by health care setting.Although there was greater use of RS for patients who sought care in more than one health care setting, use of chemotherapy followed RS guidance in University and Community health care systems. These results suggest that precision medicine may help optimize cancer treatment across health care settings.

    View details for DOI 10.1200/JOP.2015.009803

    View details for PubMedID 27221993

    View details for PubMedCentralID PMC4957259

  • Pre-treatment non-target lung FDG-PET uptake predicts symptomatic radiation pneumonitis following Stereotactic Ablative Radiotherapy (SABR). Radiotherapy and oncology Chaudhuri, A. A., Binkley, M. S., Rigdon, J., Carter, J. N., Aggarwal, S., Dudley, S. A., Qian, Y., Kumar, K. A., Hara, W. Y., Gensheimer, M., Nair, V. S., Maxim, P. G., Shultz, D. B., Bush, K., Trakul, N., Le, Q., Diehn, M., Loo, B. W., Guo, H. H. 2016; 119 (3): 454-460


    To determine if pre-treatment non-target lung FDG-PET uptake predicts for symptomatic radiation pneumonitis (RP) following lung stereotactic ablative radiotherapy (SABR).We reviewed a 258 patient database from our institution to identify 28 patients who experienced symptomatic (grade ⩾ 2) RP after SABR, and compared them to 57 controls who did not develop symptomatic RP. We compared clinical, dosimetric and functional imaging characteristics between the 2 cohorts including pre-treatment non-target lung FDG-PET uptake.Median follow-up time was 26.9 months. Patients who experienced symptomatic RP had significantly higher non-target lung FDG-PET uptake as measured by mean SUV (p < 0.0001) than controls. ROC analysis for symptomatic RP revealed area under the curve (AUC) of 0.74, with sensitivity 82.1% and specificity 57.9% with cutoff mean non-target lung SUV > 0.56. Predictive value increased (AUC of 0.82) when mean non-target lung SUV was combined with mean lung dose (MLD). We developed a 0-2 point model using these 2 variables, 1 point each for SUV > 0.56 or MLD > 5.88 Gy equivalent dose in 2 Gy per fraction (EQD2), predictive for symptomatic RP in our cohort with hazard ratio 10.01 for score 2 versus 0 (p < 0.001).Patients with elevated pre-SABR non-target lung FDG-PET uptake are at increased risk of symptomatic RP after lung SABR. Our predictive model suggests patients with mean non-target lung SUV > 0.56 and MLD > 5.88 Gy EQD2 are at highest risk. Our predictive model should be validated in an external cohort before clinical implementation.

    View details for DOI 10.1016/j.radonc.2016.05.007

    View details for PubMedID 27267049

  • Exact confidence intervals in the presence of interference STATISTICS & PROBABILITY LETTERS Rigdon, J., Hudgens, M. G. 2015; 105: 130-135
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