Seroadaptive Tactics Adopted by HIV+ MSM Can Contribute to Profound and Sustained Reductions in HIV Transmission Risk following HIV Diagnosis

Published: March 24, 2011

Background:  Previous studies have suggested that initial reductions in risk behavior after HIV diagnosis are not sustained. We investigated how seroadaptive tactics, including fewer total partners, serodiscordant partners, and “risk partnerships” (defined as insertive unprotected anal intercourse with an HIV– or partners unknown status), adopted by HIV+ men who have sex with men (MSM) influence HIV transmission risk over time.

Methods:  MSM with acute/recent (<6 months) HIV infection were enrolled from 1998 to 2010 into the OPTIONS cohort. During 2009 to 2010, at every 3-month interval, subjects completed computer-assisted self-interviews detailing risk behavior in the prior 3 months. To assess the relationship between transmission risk and time, we categorized individuals as being in the pre-diagnosis, post-diagnosis (as long as 6 months post-diagnosis), or later follow-up period based on their first interview. We calculated the mean number of partnerships for each category. Trends over time were assessed in subsets of individuals with data at multiple time points using linear regression.

Results:  In 504 interviews, 237 MSM contributed data:  52 (10.3%) interviews assessed behavior pre-diagnosis, 65 (12.9%) post-diagnosis, and 387 (76.8%) in follow-up. The mean number of sexual partners per 3 months was significantly higher pre-diagnosis (12.2) than post-diagnosis (3.8) and follow-up (7.5) periods. The proportion of reported partners who were HIV– or of unknown status was 0.80 pre-diagnosis, 0.24 post-diagnosis, and 0.62 in follow-up. Mean “risk partnerships” per 3 months was 2.80 pre-diagnosis, but was significantly lower in both post-diagnosis (0.09) and follow-up (0.20) groups. The estimated risk reduction associated with being in the follow-up vs pre-diagnosis group was 93% (p = <0.0001). If partnerships were considered risky only when a subject was viremic (plasma viral load >500), the mean numbers of risk partnerships (2.80 in the pre-diagnosis group) were significantly lower in both post-diagnosis (0.09) and follow-up (0.03) groups, resulting in a 99% estimated risk reduction between pre-diagnosis and follow-up (p <0.0001). From 6-month post-diagnosis to 12 years of follow-up, there were no trends to increase in total or risk partnership rates over time.

Conclusions:  Among recently infected individuals with high-risk sexual behavior at baseline participating in the OPTIONS cohort, patterns of sexual behavior were consistent with dramatic and sustained reductions in HIV transmission risk related to adoption of seroadaptive tactics. Improving early diagnosis of HIV infection would empower MSM to further decrease their risk of transmitting HIV, a behavior change that is clearly achievable.

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