Gender differences in viral load by CD4 count in men and women

Polly Clayden, HIV i-Base

Previous research has found that CD4 count-adjusted viral load is approximately 0.2 log copies/mL greater in men compared to women. But these data have been largely limited to industrialised countries.

The PEARLS study of the ACTG (a randomised clinical trial of antiretroviral efficacy) provided an opportunity to compare men and women with CD4 <300 cells/mm3 prior to initiation of antiretroviral therapy (ART) from 8 resource-limited countries and the United States.

A poster authored by Beatriz Grinsztejn and coworkers from the PEARLS study team showed findings from a comparison of characteristics of men and women with advanced HIV in Africa, Asia, the Caribbean and North and South America. The aim was to assess whether gender-associated differences in viral load are constant in diverse HIV-positive populations. This comparison enrolled 1571 (831 men and 740 women) drug naive (no more than 7 days of culmulative prior therapy) patients.

The investigators reported that within 45 days prior to ART initiation, compared to women, men were older, had lower body mass index, platelet and CD4 counts, but higher albumin, hemoglobin, and creatinine clearance (p<0.001 for all comparisons).

Controlling for CD4 count and stratifying by country, men had greater odds of any prior AIDS diagnosis (OR 2.1, 95%CI 1.4 -3.3), PCP (OR 4.5, 95%CI 1.0- 20.0), and herpes simplex ulcers (OR 3.0, 95%CI 1.1-7.7).

Unadjusted mean viral load was 5.05 log10 copies/mL in men compared to 4.85 log10 copies/mL in women (p <0.001).

Table 1: Men vs women difference in viral load by CD4 count adjusted for ethnicity, country and history of AIDS

Baseline CD4 Men vs women mean viral load difference (log10 copies/mL) 95% CI for difference
50 0.8 -0.03 – 0.18
100 0.12 0.03 – 0.20
150 0.15 0.09 – 0.22
200 0.19 0.09 – 0.22
250 0.23 0.09 – 0.22

The investigators noted that prior antiretroviral use did not explain lower viral loads in women: in this study only 8.2% women reported any previous use (largely single dose NVP) and only 4.7% had more than 7 days previous antiretroviral exposure.

The investigators concluded: “Our analyses suggest that gender-associated viral load differences are more likely to be associated with inherent biological differences in men and women than with factors linked to geographic location including race, co-infections, culture, or environment.”


Grinsztejn B, Smeaton L, De Gruttola V et al. Gender-associated differences in pre-ART plasma HIV-1 RNA in diverse areas of the world vary by CD4+ cell count. 15th CROI. February 2008. Boston, USA. Poster abstract 672.

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