MSM and Drug Use: A Latent Class Analysis of Drug Use and Related Sexual Risk Behaviors
Methods: We analyzed Internet survey data collected as part of the 5-year, CDPH-funded CRYSTAL Prevention Project. MSM participants who completed this survey (n=943) reported any past year use of alcohol, illegal drugs (poppers, methamphetamine, cocaine, marijuana, hallucinogens, club drugs) and non-prescription use of erectile dysfunction drugs (EDD), tranquilizers, and analgesics. A latent class analysis classified respondents based on use patterns. The best fitting latent class model was determined using the Bayseian Information Criterion and interpretability of the classification results. Class membership became the dependent variable in a multinomial regression. Model predictors were HIV status, psychological distress, social support, and sexual behaviors associated with risk of HIV transmission, including engagement in unprotected insertive (IUAI) and receptive anal intercourse (RUAI) and payment or receipt of money for sex.
Results: A four-class model was selected. Sixty-three percent of respondents were classified as having low drug use (LDU) and another 24% as moderate use (MDU). The model included two distinct high-use classes: HDU1 (3%) and HDU2 (9%). HDU1 members had high probabilities of using all drugs assessed. Over 50% of those in HDU1 reported using alcohol, marijuana, cocaine, tranquilizers, club drugs, hallucinogens, analgesics, and poppers. In contrast, HDU2 members concentrated use on the so-called “sex-drugs”: methamphetamine, alcohol, poppers, and EDDs. The multinomial regression revealed that high levels of psychological distress were associated with 1.08 higher log odds of being in HDU1 compared to HDU2. Conversely, individuals reporting being HIV positive, engaging in IAIU, or exchanging money for sex had lower log odds of being in HDU1 compared to HDU2.
Implications: This study identified two drug use classes of MSM at potentially high-risk for HIV/AIDS or other STIs, each with distinct patterns of drug use and associated sexual health risks. Those in HDU1 demonstrate greater psychological distress, suggesting they may be harder to maintain in services, and are in need of targeted mental health interventions. Those in HDU2 are more likely to engage in particular high-risk sexual behaviors, suggesting their drug use enhances or permits potentially risky sexual activity, and could benefit from risk reduction interventions focused on intersections between drug-use and sexual activity