Abstract
BACKGROUND: Prior research has shown that men who have sex with men (MSM) who use drugs are at increased risk of sexually transmitted infections (STI) and Human Immunodeficiency Virus (HIV). Often, MSM who use drugs use multiple substances at once and research has indicated that certain substances are used in combination more frequently. As a vulnerable population, it is important to understand the various ways in which this population uses drugs in order to structure prevention, harm reduction, and treatment programs to their needs. METHODS: Data for this analysis were taken from a cohort of geographically diverse U.S. national sample of cisgender men who have sex with men (n = 6111). After assessing prevalence of drug use in the sample, we used iterative latent class analysis to determine substance use classes for 10 substances. After a model was selected, class assignments were examined for association with mean number of insertive and receptive condomless anal sex (CAS) partners in the past three months. RESULTS: The final model indicated six latent classes: class 1 = "cannabis use" (n = 1,996), class 2 = "diverse use" (n = 299), class 3 = "cocaine and inhalant use" (n = 421), class 4 = "methamphetamine, GHB, and inhalant use" (n = 345), class 5 = "no use" (n = 2431), class 6 = "sedative use" (n = 619). Age, race, annual income, residence in EHE jurisdictions, past history of houselessness, and past history of incarceration was significantly associated with membership in some classes. In outcome modeling, participants best assigned to Class 4 had the highest mean number of insertive (Mean = 9.70, 95% CI: 5.92 - 13.47) and receptive (Mean = 8.71, 95% CI: 6.75 - 10.66) condomless anal sex (CAS) partners in the prior three months. CONCLUSION: The six heterogenous classes may indicate discrete typologies of use behavior corresponding to different settings or activities, which may themselves differ by regional HIV incidence trends and participant demographics. Programs seeking to address substance use among MSM may be well served to tailor toward these divergent clusters of substance use.