HIV Incidence in a New Generation of YMSM: Lessons from the P18 Cohort Study

Background: Young gay, bisexual and other YMSM continue to be at high risk for HIV infection.

Methods:  A cohort study of 600 YMSM ages 18-19 at baseline was enacted and included 7 waves of data collection over a 36-month period. HIV antibody testing was conducted at each assessment and behavioral, psychosocial, and environmental/structural factors were measured. HIV incidence data were calculated and correlates of HIV infection were examined in relation to these factors.

Results: At baseline, prevalent cases of HIV infection were detected in 1% of the study sample. Over the course of six additional waves of data collection, cumulative incidence for HIV infection was 7.23% and mean age at seroconversion was approximately 20. HIV seroconversion was highly related to race/ethnicity both with regard to baseline prevalence and incidence. Cumulative incidence was calculated at 17.98% for Black Non Hispanic men, 8.92% for mixed race men most of whom identified one race as Black, 6.99% for Hispanic men and 1.7% for white Non Hispanic men. Lower SES was highly associated with HIV infection. No differences were noted in unprotected sexual behavior, and a high level of racial concordance was noted between YMSM and both main and causal sex partners.

Conclusions: Findings align with epidemiological trends in HIV infection among YMSM over the last decade. Coupled with our behavioral data, these findings further suggest the likelihood that unsuppressed viremia among low SES racial/ethnic minority MSM is likely the critical component in explaining heightened level of HIV incidence is this segment of the population.