HIV incidence among MSM: defying primary prevention
In Western European countries sex between men regains importance as a driving force of the HIV epidemic: in Portugal newly-diagnosed HIV cases among MSM have increased 6% per year, whereas cases due to the remaining transmission modes have decreased. New infections among MSM may result from risk management strategies that bypass classic primary prevention. We aimed to estimate the incidence of HIV infection in a cohort of HIV-negative MSM and to identify its individual-level predictors.
METHODS:
We studied an ongoing dynamic cohort of HIV-negative MSM who present for testing at a peer-based voluntary counseling and testing center in Lisbon, Portugal (CheckpointLX). Men testing negative are invited to participate and follow-ups are scheduled according to their convenience. Evaluations comprise rapid HIV testing and a behavioral questionnaire. Between April 2011 and May 2013, 498 MSM were followed for a total of 429 person-years. Associations between baseline characteristics and HIV seroconversion were calculated using Cox proportional hazards model and presented as hazard ratios (HR) and 95% confidence intervals (95% CI).
RESULTS:
The incidence rate of HIV was 3.5/100 person-years (95% CI: 2.11; 5.80). Men who seroconverted were more likely concerned about recent HIV exposure at their first negative result (3.28; 1.04, 10.30) and to use recreational drugs during intercourse (4.69; 0.99, 22.16). Non-significant but strong associations were found between seroconversion and history of testing prior to cohort entry (2.06; 0.27, 15.79) and recent intercourse with HIV-positive men (2.62; 0.59, 11.72). There were negligible associations between seroconversion and age, education, country of birth and condom use in the last intercourse with a steady or occasional partner.
CONCLUSIONS:
This first incidence study in Portugal emphasizes the major role of individual risk management. Tackling new infections demands to acknowledge the challenging issue of testing as prevention.