No gender-based difference in response to HIV treatment

A new study has found that men and women react to anti-HIV drugs in a similar way.

The study demonstrated it is possible to recruit large numbers of women into a clinical trial evaluating treatments for HIV infection and found no significant gender-based differences in response to the anti-HIV drugs darunavir and ritonavir - at least among those who remained in the trial to the end.

However, women dropped out of the GRACE (Gender, Race and Clinical Experience) study at higher rates than men for reasons other than drug failure, indicating that more must be done to retain women in clinical trials that shed important light on the effectiveness of drugs in development or those on the market.

The study has shown that nearly one-third of women dropped out, compared with less than one-fourth of the men enrolled.

"It is critical that women are involved in clinical trials to evaluate the efficacy and toxicity of new treatment - not just for HIV but for all diseases," said Judith Currier of UCLA.

Conducted between 2006, and 2008, at 65 sites in the United States, Puerto Rico and Canada, the study examined the drugs' effectiveness, their adverse effects and tolerability in both men and women.

The researchers recruited 429 HIV-positive subjects who had previously taken HIV therapy. Of the subjects, 287 (66.9%) were women and 142 (33.1%) were men.

Overall, 84% were black or Hispanic. In most treatment studies of HIV medications, women account for less than 25% of participants.

The study participants received 600 mg of darunavir and 100 mg of ritonavir twice daily.

The percentages of women and men who were able to suppress the HIV virus during the study were generally similar.

However, a significantly higher proportion of women than men discontinued the study (32.8% vs. 23.2%).

When the researchers examined the treatment response of all the participants who entered the trial - including those who eventually dropped out - they found that response rates in women appeared lower than response rates in men (50.9% vs. 58.5%).

But this difference appeared to be due to the higher drop-out rate among women.

When they excluded participants who discontinued the study for reasons other than virologic failure, the response rates were similar in women and men (73.0% vs. 73.5%).

Adverse side effects were also comparable between the sexes.

"The GRACE study shows that it is possible to enroll large numbers of women into HIV treatment trials. The higher discontinuation rate in women, which was driven by reasons other than virologic failure, highlights the need for additional efforts to retain diverse populations in studies," the researchers concluded.

The findings were published in the journal Annals of Internal Medicine.