Study shows gender differences in progression of HIV to AIDS

During the first years of HIV infection, women have significantly lower amounts of the virus in their blood than men, according to one of the largest studies ever to examine gender-specific differences in HIV infection. Despite their lower initial viral levels, women suffer the loss of immune cells and develop AIDS just as swiftly as men. The findings, reported in The New England Journal of Medicine (vol. 344, no. 10), lend further support to recent changes in the criteria used to help doctors tailor anti-HIV drug therapy to delay the onset of AIDS.

The researchers found that the median initial viral load of the women who progressed to AIDS was almost five times lower than that of the men who progressed to AIDS.

"Despite early differences in viral load among men and women, as time went on, both men and women had a similar risk of developing AIDS," said Timothy Sterling, assistant professor of medicine and epidemiology at Hopkins and the first author of the study. "In addition, men and women experienced a similar rate of loss of their CD4+ T cells, the immune cells that decrease as a result of HIV infection." Co-author Thomas C. Quinn, a senior investigator in the National Institute of Allergy and Infectious Diseases' Laboratory of Immunoregulation and professor of medicine at Hopkins, said, "Previous studies in men have shown that initial viral load can be used to gauge their likelihood of progression to AIDS, but these data confirm that the initial viral load is much lower in women than in men and consequently not as predictive for women."

Lower viral loads

Between 1988 and 1998, the team followed a group of 156 men and 46 women who were HIV positive. During that time, 29 men and 15 women developed AIDS. The research team measured the volunteers' HIV load at regular intervals, starting from around the time they became infected.

The investigators found that the women who developed AIDS had a median initial viral load of 17,149 copies of virus per milliliter of blood, about 4.5 times lower than the median level found in men who progressed to AIDS (77,822 copies/ml). Even men in the group who never developed AIDS had a higher median initial viral load of 40,634 copies/ml.

The women's lower viral levels meant that early after HIV infection, a smaller percentage of them would have been eligible to start treatment with anti-HIV drugs, based on clinical recommendations available at the time of the study. Those recommendations are reviewed regularly and have been updated recently.

"This research forms part of the body of data reviewed in forming the latest HIV treatment guidelines," said Anthony S. Fauci, director of NIAID. "It's important to conduct such studies that can give us a clearer picture of the unique challenges HIV/AIDS poses to women's health, because so many new cases of this disease are occurring among women, and among minority women in particular." PR