September 30, 2008 - By Ruthann Richter
A simple test given to HIV/AIDS patients in southern Africa could extend their lives by nearly a year and save health-care costs at the same time, according to a new study by researchers at the medical school and the Palo Alto Veterans Affairs Health Care System.
The technique, known as the CD4 test, would be particularly valuable if it were given to patients early in their disease, before they became ill with an AIDS-related infection, the researchers found. Use of the test could prevent patients from developing these life-threatening complications and save on costly hospitalizations.
'It's a real opportunity,' said senior author Douglas K. Owens, MD, senior investigator at the Palo Alto-VA and a professor of medicine and of health research and policy.
Eran Bendavid, MD, the first author on the paper, said the study could help organizations that provide antiretroviral, or ARV, therapy in Africa, where two-thirds of the world's 33 million HIV patients live. 'We hope public health officials and clinicians understand that the test is a technology worth investing in,' said Bendavid, a postdoctoral scholar in infectious diseases and in health research and policy. The study appeared in the Sept. 22 issue of Archives of Internal Medicine.
In recent years, government and private organizations have responded to the urgent need to step up access to ARVs, providing this life-prolonging treatment to some 3 million HIV/AIDS patients worldwide, most of them in Africa. With drug access now increasing, clinicians need to know how best to manage these patients, including when to start them on treatment and when to change their drug regimen, if necessary, Owens said.
To help address these questions, the study examined the costs and health benefits of managing HIV/AIDS patients in southern Africa with CD4 and one other form of testing, viral load, over their lifetimes.
Today, caregivers in Africa typically monitor patients by observing their symptoms, starting them on drug therapy when they develop an opportunistic infection, such as tuberculosis or pneumonia.
But there are other, more sophisticated methods of tracking the course of a patient's disease. These include the CD4 test, which measures the number of these crucial, disease-fighting cells of the immune system. CD4 cells are targeted by the AIDS virus and, as their numbers decline, patients become more prone to developing life-threatening infections. The CD4 test is quick to administer and may require only a simple finger prick to obtain blood that is then analyzed in a cell sorter, a desktop machine about the size of a personal computer, Bendavid said. Results can be available in as little as 10 minutes.
In the study, the researchers used a mathematical model to analyze the costs and benefits of using different methods to track the patients' disease. The model was based on data from two groups of patients in Capetown, South Africa, though the analysis takes into account the regional differences across southern Africa. The researchers evaluated patients who were followed based on symptoms alone, as well as those who received the CD4 and viral load tests. The scientists then calculated the relative costs of each of these strategies.
They found that patients who received a CD4 test alone lived 11.8 months longer than those who were monitored on the basis of their symptoms alone. Patients fared best when given the test and then started on therapy early - when their CD4 cells numbered 350, rather than waiting until they fell to 200. Patients in the early treatment group had 18 percent fewer opportunistic infections and were less likely to be hospitalized. The cost savings per patient amounted to $417, compared with those who were monitored on the basis of symptoms alone.
Use of the CD4 test could have sweeping benefits across southern Africa, where between 3 and 5 million people need ARVs, Bendavid said. If the test were applied in a population of a million patients, these individuals would gain a collective 982,000 years of life, an enormous benefit by any standard, the researchers said.
Currently, the test is available on a limited basis in southern Africa. Expanding access to the test would require government and private organizations to invest in the cell sorters, which cost about $30,000, and then train personnel to use them. 'It's time to find ways to reduce those barriers,' Owens said.
The U.S. President's Emergency Program for AIDS Relief is now making CD4 tests available as part of its programs, Bendavid said. The Clinton Foundation, which has negotiated pricing agreements that benefit 1.4 million patients, is also working to expand access to CD4 testing, said Trevor Peter, a foundation official.
Stanford collaborators on the study are David Katzenstein, MD, professor of infectious diseases, and Sean Young, a PhD student in psychology. Other collaborators include Ahmed Bayoumi, MD, at the University of Toronto, and Gillian Sanders, PhD, a former Stanford faculty member now at Duke University. The research was supported by the National Institutes of Health, the Agency for Healthcare Research and Quality and the Department of Veterans Affairs.
Stanford Medicine integrates research, medical education and health care at its three institutions - Stanford University School of Medicine, Stanford Health Care (formerly Stanford Hospital & Clinics), and Lucile Packard Children's Hospital Stanford. For more information, please visit the Office of Communication & Public Affairs site at http://mednews.stanford.edu.