Background: The most widely used estimate of condom efficacy (80%, Cochrane Review) was based on meta-analyses of cross-sectional and longitudinal studies of persons reporting “always” use or “never” use during heterosexual sex in preventing HIV infection. We assessed male condom efficacy during anal sex between men who have sex with men (MSM) in 2 prospective US HIV incidence studies, by self-reported consistency of use.

Methods: We analyzed data combined from 1244 men in the EXPLORE study public use dataset and 2713 US participants in the VAX004 trial who met analysis eligibility criteria. At baseline and each semiannual visit, initially HIV^– MSM enrolled in these HIV prevention trials completed interviews about their sexual behaviors with male partners and underwent HIV testing. Using a time-to-event model, efficacy of condom use in preventing HIV infection was estimated among men reporting receptive and/or insertive anal sex with an HIV⁺ partner, and consistency of condom use (always = 100%, sometimes = 1-99%, never = 0%) for comparability to the Cochrane review for condom efficacy with heterosexuals.

Results: Among MSM reporting any anal sex with an HIV⁺ male partner, we found 67% efficacy with consistent reported use of condoms (compared to never use) and no significant protection when comparing sometimes use to never use (Table). Among MSM in these studies, 48.0% reported always use, 29.3% inconsistent use, and 22.7% never use of condoms for at least one 6-month interval during receptive or insertive anal intercourse with  partners of any HIV status. A total of 39.6% reported always use, 47.2% reported inconsistent use, and 13.2% never use across all their study visits.

Conclusions: When comparing reported always use to never use of condoms, the estimated efficacy of condoms (67%) among MSM reporting any anal sex with an HIV⁺ partner is less than the overall efficacy estimated for heterosexuals (80%). Additionally, because a minority of MSM report consistent condom use over 1-2 years, they are unlikely to achieve the levels of protection that short-term measures of consistent use would suggest.