The Longitudinal Patterns of Stimulant and Amyl Nitrite Use and Sexual Behavior Pre- and Post-HIV Seroconversion among MSM

Background and Aims. This study compared the temporal patterns of stimulant/nitrite use and risky sexual behavior for 3 groups of MSM: those who seroconverted during the study; those who remained HIV-seronegative; and HIV seroprevalent individuals whose infections preceded study enrollment. Setting. Data were collected in Baltimore-Washington, DC; Pittsburgh; Chicago; and Los Angeles sites of the Multicenter AIDS Cohort Study (MACS), a longitudinal study of the natural history of HIV infection among MSM. Participants. We used propensity scores to obtain 1,044 MSM composed of matched groups of 348 seroconverting, 348 seronegative, and 348 seroprevalent participants, matched on demographics, recruitment cohort, and study visits. Design. We centered up to four-years of semi-annual data around the seroconversion visit of the seroconverting case within each matched group of participants. Mixed effects regressions estimated the effects of serostatus, recruitment cohort, and time on stimulant/nitrite use, numbers of male intercourse partners, and numbers of unprotected receptive anal intercourse (URAI) partners. Covariates included demographics, binge drinking, and marijuana use. Findings. Seroconverters had the higher odds of stimulant/inhaled nitrite use (AOR=10.3, CI=4.8-22.0) and higher incident rates of intercourse (IRR=1.6, CI=1.3-2.1) and URAI partners (IRR = 5.1, CI=3.5-7.3). All participants decreased drug use and sexual risk behavior over time. However, the decreases were largest for seroconverters who nevertheless maintained the highest rates of stimulant use and sexual risk. Cohort-related effects were associated with sharp reductions in stimulant/nitrite use and URAI in the early 1990s that rebounded considerably within the first decade of the 2000s. Conclusions. Risky sexual behavior and stimulant/nitrite use decrease following HIV infection although seroconverting participants persist using stimulants and engaging in risky sex at relatively high levels/rates albeit less than the level/rates preceding infection. Against this general pattern there is significant variation at the individual level. Moreover, stimulant/nitrite use and risky sexual behavior appear to have been strongly influenced by contextual historical and socio-cultural effects.