HIV viral load levels in women stabilise at a lower level than in men following seroconversion, Dr T Sterling of John Hopkins University reported yesterday at the World AIDS Conference in Durban.
These sex-based differences in viral load have implications for women’s access to treatments and clinical trials, researchers told a session on gender issues and HIV.
Dr Sterling studied initial viral load levels in 202 individuals who contracted HIV between March 1989 and December 1998. All had been enrolled in the ALIVE study – a large cohort of injecting drug users in the US.
The average viral load after seroconversion in men who progressed to AIDS was 77,822 copies/ml and 40,634 copies/ml in men who did not progress (p=0.009). However, initial viral load levels were significantly lower in women. Women who progressed had a median viral load of 17,149 copies/ml in comparison to 12,043 copies/ml in women who did not progress (p=0.21). The difference in viral load between women who progressed and those who did not progress was not statistically significant. Therefore the level of viral load after seroconversion in women did not predict the risk of developing AIDS.
“Initial HIV-1 RNA level after seroconversion is lower in women than men and remains so after controlling for CD4 count, age and time between seroconversion and first viral load,” Dr Sterling said. “So we feel that this fairly conclusively demonstrates that there is indeed a sex difference in viral load.”
“Quantitatively, the same absolute viral load measurement after seroconversion does not convey the same risk of AIDS in men and women,” Dr Sterling said.
Consequently, Dr Sterling and others expressed doubt about whether current estimates of progression risk based on viral load levels are relevant to women. Keynote speaker Dr K Squires said, “The efficacy of those surrogate markers has been established almost exclusively in male cohorts.”
Dr Squires said that it was still an open question whether data from those cohort studies are relevant to women and she called for further research into women and markers of disease progression.
Dr Sterling said that viral load differences impact on women’s ability to access antiretroviral therapy and clinical trials. “The viral load cut-offs in the current guidelines result in sex based differences in eligibility to antiretroviral therapy despite the same age risk,” Dr Sterling said. “The guidelines on viral load cut-offs in eligibility [for treatment]need to be reassessed, particularly early in the course of HIV infection.”
Dr K Squires commented that these differences in viral load levels also impact on women’s inclusion in clinical trials, because they may be excluded from studies which recruit individuals with viral load above 10,000 copies/ml, despite having a higher risk of disease progression at that level than men.
However, despite women’s lower initial viral load, the risk of AIDS is the same for men and women as viral load rises. For every log increase in viral load, women and men experience the same increased risk of progression.
Sterling T et al. Initial HIV-1 plasma RNA after seroconversion does not predict progression to AIDS in women. XIIIth International AIDS Conference, Durban, abstract B402, 2000.