Despite Differences in Viral Load, Men and Women Have Similar Risk of Developing AIDS, Study Says
While HIV-positive women maintain lower viral levels than men in the first few years of infection, they suffer loss of CD4+ cells and progress to AIDS at the same rate, according to a study published in today's issue of the New England Journal of Medicine. Researchers from the National Institute of Allergy and Infectious Diseases and Johns Hopkins University followed more than 200 intravenous drug users in the AIDS Linked to the Intravenous Experience, or ALIVE, cohort, which was established in 1988 as a "natural history study of HIV disease among injection drug users," NIDA Director Alan Leshner said. Between 1988 and 1998, researchers monitored 156 men and 46 women who became HIV positive in this cohort, and measured patients' HIV viral loads (using the RT-PCR test) at regular intervals. Over the 10-year period, 29 men and 15 women progressed to AIDS. Researchers found that women who developed AIDS had a median initial viral load of 17,149 copies of virus per milliliter of blood, compared to 77,822 copies per milliliter in men. Even men who did not develop AIDS had a higher median initial viral load than the women who developed AIDS, at 40,634 copies per milliliter. But despite the difference in viral load levels between men and women, both genders showed a similar rate of loss of CD4+ cells (NIH release, 3/7). Lead study author Dr. Timothy Sterling, assistant professor of medicine at Johns Hopkins University School of Medicine's Division of Infectious Diseases, said, "This sex difference in initial viral load means that the same viral load measurement does not convey the same risk of AIDS in women and men. For example, in this study, an initial viral load of 17,149 copies per milliliter was associated with progression to AIDS in women but not in men. In men, a viral load as high as 40,634 copies per milliliter was not associated with progression to AIDS."
Researchers noted that this distinction had "important" implications for antiretroviral treatment guidelines. Until recently, these guidelines suggested initiation of antiretroviral therapy when viral load exceeds 20,000 copies per milliliter, which would have excluded most women in the ALIVE cohort. The current guidelines state that treatment should be considered when viral load levels reach 55,000 copies per milliliter, a recommendation that would exclude even more women. However, treatment guidelines based on CD4+ cell counts would not lead to a sex difference in treatment eligibility. Senior co-author Dr. Thomas Quinn, professor of medicine at Johns Hopkins University School of Medicine's Division of Infectious Diseases, said, "The results of this study suggest that greater emphasis should be placed on CD4+ count than viral load when deciding when to initiate treatment. These findings are consistent with the revised new guidelines, which recommend that antiretroviral therapy be initiated for both men and women when the CD4+ ... count is less than 350 cells per millimeter cubed" (Johns Hopkins School of Public Health release, 3/7). Quinn added, "More studies on the dynamics of HIV infection could give us a better idea of when to start drug therapy to delay the onset of AIDS in people with HIV." An NIH release notes that the study represents "one of the largest studies ever to examine gender-specific differences in HIV infection" (NIH release, 3/7).