Women have significantly better response to HIV therapy than men

Adam Legge
Published: 03 May 2007

Women have a significantly better response to HIV treatment than men say the Spanish authors of the latest big study into gender bias in HIV outcomes published in the April 23rd edition of AIDS.

The first suggestions than men and women differ in their responses to HIV infection were made over 15 years ago. A number of studies since have reported conflicting findings. The researchers behind the new study have attempted to clarify the issue by concentrating on a large group of patients from 69 Spanish hospitals who all started on similar treatments. They collected data on 2,620 HIV-infected people – 72% of them men – for twelve months after they started taking similar nelfinavir-based antiretroviral regimens.

Among those who were taking potent HIV therapy for the first time, the women’s average CD4 cell count was higher than the men’s (p = 0.01). Although the women were more likely to achieve undetectable viral loads the difference was not statistically significant (p = 0.6). The gender difference was more marked in the treatment-experienced group where again women’s average CD4 cell counts were higher than men’s, but the difference was of only borderline statistical significance (p = 0.06) At twelve months 49% of the treatment-experienced women had undetectable viral loads compared to 40% of the men (p = 0.01).

At every time-point studied throughout the twelve months women had consistently better virological and immunological responses than men despite the fact they were significantly more likely to experience side-effects to the regimen. HIV disease also progressed more slowly in women.

None of these differences could be explained by women being more adherent to the drug therapies, the researchers concluded (Collazos 2007).

In general the women tended to have lower viral loads and higher CD4 cell counts when they began therapy but the differences seen in this study are also due to stronger immunological responses to therapy, they add.

Previous studies into a possible gender bias in HIV outcomes have produced varying conclusions. Some have found higher CD4 counts in men and others in women while others have found no difference.

The authors of this study say it has several advantages over others, including its size. Ethnic or racial factors are less likely to have an influence as 90% of the individual studied were white Spanish. And the fact that 69 hospitals across Spain were used minimises the risk of treatment bias from one centre.


Collazos J et al. Sex differences in the clinical, immunological and virological parameters of HIV-infected patients treated with HAART. AIDS 21: 835-843, 2007.

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