In a Way, AIDS Does Discriminate Between the Sexes
"You would assume that if women start out with a lower viral load than men, they would have a lower risk of progressing to AIDS, but they have the same risk," says Timothy Sterling, MD, an assistant professor of infectious diseases at the Johns Hopkins Medical Institutions in Baltimore.
In a presentation here at the 13th International AIDS Conference, Sterling and colleagues said they enrolled more than 3,300 HIV-negative intravenous drug abusers in the study. Eventually, about 200 of them became HIV-positive -- 156 men and 46 women.
Twenty-nine men and 15 women went on to develop AIDS even though, at the time, the men's average viral load was more than four times that of the women.
Why are these findings a concern?
Currently, doctors generally offer treatment called antiretroviral therapy to HIV-positive patients when the virus reaches a certain level in the blood. The women in the study had not yet reached those levels to qualify for treatment -- before and even after their HIV progressed to AIDS.
Therapy is also considered when special cells in the body, called CD4 cells, drop below a count of 500. In the study, there were no significant differences in CD4 cell counts of the men and women.
Sterling suggested that because some women have low viral loads they will not receive antiretroviral therapy even though they are still at risk of developing AIDS.
"The current viral load cutoffs for the initiation of antiretroviral therapy were developed based on data from men," said Sterling. "This study demonstrates that current cutoffs would result in sex-biased differences in treatment eligibility, and that therefore current guidelines should be reassessed, particularly early in the course of infection."
Over the past several years, various studies have yielded conflicting results as to whether viral loads differ between HIV-positive men and women. "The jury is still out on exactly what these studies mean," says Scott Holmberg, MD, a senior epidemiologist at the CDC.
John Nkengasong, MD, chief of Laboratoire de Virologie in West Africa, says he had also investigated differences between men and women and their viral loads. However, after analyzing 1,800 patients he was unable to find an outcome difference between the sexes. Nkengasong does suggest, though, that the differences in viral load and the possible effect on therapy guidelines need further study.