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MULTICENTER AIDS COHORT STUDY IMPROVES PROGNOSTIC TOOLS FOR AIDS AND HIV-INFECTED PATIENTS
PITTSBURGH, June 12 -- The development of effective treatments for some AIDS patients within the past few years has presented physicians with the new dilemma of when to initiate therapy.
A report in the June 15 issue of Annals of Internal Medicine shows for the first time that the use of two tests in combination -- viral load measurement and CD4 T cell counts -- more accurately determines the time for an HIV-infected individual to develop AIDS (as defined by the CDC).
These findings were reported by John Mellors, M.D., co-investigator of the Pittsburgh site of the Multicenter AIDS Cohort Study (MACS) and associate professor of medicine at the University of Pittsburgh, and Alvaro Munoz, Ph.D., co-investigator of The Johns Hopkins site of MACS and professor of epidemiology at The Johns Hopkins University. Drs. Mellors and Munoz led the research in collaboration with colleagues from two other centers involved in the National Institute of Allergy and Infectious Diseases MACS project.
"Rather than guessing about when a patient with HIV infection will develop AIDS, we can now look into the future with much greater accuracy," said Dr. Mellors. "These findings will enable physicians to assess the risk of AIDS for individual patients. This is especially crucial for deciding when to initiate antiretroviral therapy."
By measuring the amount of genetic material in circulating virus, referred to as plasma viral load or HIV-1 RNA, Dr. Mellors and his colleagues have confirmed their previous finding that viral load is the single best predictor of progression to AIDS and death from AIDS.
In this study, the analysis of blood samples from 1,604 HIV-infected men showed that the predictive power of viral load is enhanced when combined with counts of CD4 cells, said Dr. Mellors. CD4 cells, an integral part of the immune system's defense to foreign invaders, are attacked and destroyed by the AIDS virus.
Researchers assigned each patient into one of 12 distinct categories of AIDS risk that were defined by both viral load measurements and CD4 counts. They found that only 1.7 percent of patients in the lowest risk category -- the lowest viral load measurements (500 copies/mL or less) and highest CD4 counts (greater than 750 cells/mm3) -- developed AIDS within 6 years. By contrast, 97.9 percent of those with the highest amount of virus (greater than 30,000 copies/mL) and lowest CD4 counts (greater or less than 200 cells/mm3) developed AIDS within 6 years.
"By incorporating this information into a decision tree, we have developed a simple and effective tool for physicians to employ in estimating patients' prognosis," said Dr. Mellors. "Like the staging of cancer, the 12 categories that we have defined will enable physicians to assess the prognosis three to nine years after infection. This information will strongly influence the decision when to start therapy."
The University of Pittsburgh is one of four centers participating in MACS. The other centers are: Howard Brown Health Clinic and Northwestern University Medical School, Chicago; and the University of California, Los Angeles.
"This study and many other MACS projects were only possible because of the unselfish efforts of more than 5,000 men, including more than 1,000 from Pittsburgh," said Charles R. Rinaldo Jr., Ph.D., director of the Pittsburgh site for MACS, known locally as The Pitt Men's Study, and chairman of the department of infectious diseases and microbiology at Pitt's Graduate School of Public Health.
HIV/AIDS researchers at the University of Pittsburgh have pioneered the use of viral load testing in HIV-infected patients, antiretroviral therapy to reduce disease activity and topical agents to prevent sexual transmission of HIV in women. Pitt investigators also are conducting research on AIDS-related malignancies and dementia, AIDS vaccines and AIDS prevention strategies.
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