Background In 2010 recent HIV diagnoses increased in the UK despite 80% of diagnosed HIV+ MSM being on antiretroviral treatment (ART) with undetectable viral load. While undiagnosed HIV infections are thought to account for high proportion of these transmissions; a significant proportion is attributed to diagnosed HIV. We examine factors associated with unprotected anal intercourse with non-concordant partners (ncUAI) among HIV+ MSM and potential for HIV prevention.

Methods HIV+ MSM attending a central London HIV clinic completed a computer-assisted survey (May-September 2010). Multivariate logistic regression analyses were conducted.

Results Median age of 429 men was 43 years. 81% of them were on ART. 17% of men had missed ≥ 1 ART doses in the last two weeks. One in five men believed that being on ART with an undetectable viral load eliminates risk of HIV transmission. 380 men had been sexually active in the last year; 20% of whom had not tested for STI. 25% of those tested had been diagnosed with ≥ 1 STI. 50% of men had a non-concordant primary partner. 50% of men’s most recent sex partner was a non-primary non-concordant partner. The prevalence of ncUAI with primary and the most recent non-primary partner was 18% and 16.9 respectively. Duration of partnership, recreational drug use during sex, belief that undetectable viral load eliminates the risk of HIV transmission were all independently associated with ncUAI with a primary partner. Disclosure of HIV status and recreational drug use during sex were independently associated with ncUAI with the most recent non-primary partner. Viral load status was not associated with ncUAI.

Conclusions HIV+ MSM attending HIV clinic reported high transmission risk behaviours. Engaging them in combination prevention interventions addressing recreational drug use, adherence to ART, attitudes towards ART for HIV prevention and STI testing during clinic visits provides vital opportunity for HIV/STI prevention.