Jun 20 2005
Researchers from the Johns Hopkins Bloomberg School of Public Health, Centers for Disease Control and Prevention and the Chiang Mai University in Thailand, evaluated the ability of inexpensive biological markers, which are obtainable in resource-poor countries, to determine which HIV-infected patients are in the greatest need of antiretroviral therapy. Cheaper diagnostic methods and knowledge of disease progression can be useful for public health practitioners trying to treat HIV patients.
The study is published in the June 2005 issue of the International Journal of Epidemiology.
“One of the major concerns for health care workers in many developing countries is deciding which of the many HIV-infected patients in their clinic needs treatment the most. Use of these less expensive markers can be helpful in guiding this treatment decision,” said Kenrad E. Nelson, MD, corresponding author of the study and a professor in the Bloomberg School of Public Health's Department of Epidemiology.
He explained that doctors in the United States typically measure the CD4-lymphocyte count and HIV-viral load to decide when to start treatment of an HIV-infected patient. However, a CD4-lymphocyte count requires an expensive instrument and trained laboratory staff and is expensive to perform. The World Health Organization (WHO) has recommended that those clinics in Africa and Asia that lack modern laboratory facilities may assume that a total lymphocyte count of 1,200 cells/ µl or less indicates that a patient's CD4-lymphocyte count is below 200 cells/ µl and that the patient therefore needs treatment.
The research group from Johns Hopkins studied 836 HIV-infected patients from Thailand enrolled in the study between 1992 and 1997. They found that nearly all patients whose total lymphocyte counts were below 1,200 cells/µl had fewer than 200 CD4 lymphocytes per µl ; more importantly, however, the scientists found that this WHO-recommended marker failed to detect about two thirds of the patients with low CD4 lymphocyte counts.
The researchers therefore evaluated additional markers that would be readily available in a resource-poor setting such as a rural, African clinic, to see if the ability to predict 200 or fewer CD4-lymphocytes, and thus the need for treatment, could be improved. Combining the total lymphocyte count with the presence of anemia and a low body-mass index substantially increased the accuracy of predicting who needed antiretroviral therapy in the study population in northern Thailand.
In this Thai population, the median survival time from HIV-infection to death was 7.8 years, significantly shorter than has been reported for HIV-infected populations in the United States and Europe. Even so, the markers evaluated, as well as the CD4 cell count, were able to reliably predict those with a poor chance of survival in this population.
The World Health Organization and many other groups are making a major effort now to provide effective antiretroviral therapy to several million HIV-infected people living in developing countries in Africa, Asia and elsewhere. The WHO also has a program, which aims to treat three million persons for AIDS in Africa and Asia by the end of 2005. To reach this ambitious goal, inexpensive and available markers must be evaluated so they can be used in resource-limited clinics to select those most in need of therapy.
The study was supported by a grant provided by the Contraceptive Research and Development Program at Eastern Virginia Medical School, which is affiliated with USAID. USAID receives funds from the Division of Reproductive Health at the Centers for Disease Control and Prevention.
Additional co-authors of the study include C. Costello, V. Suriyanon, S. Sennun, S. Tovanabutra, C.M. Heilig, S. Shiboski, D.J. Jamieson, V. Robison, K. Rungruenthanakit and A. Duerr.