Association of Injection Practices and Overdose With Drug Use Typologies: A Latent Class Analysis Among People Who Inject Drugs in Baltimore, 2017.

Increasing overdose mortality and new HIV outbreaks in the U.S. highlight the need to identify risk behavior profiles among people who inject drugs (PWID). We characterized latent classes of drug use among a community-based sample of 671 PWID in Baltimore during 2017 and evaluated associations of these classes with sharing syringes, obtaining syringes from pharmacies or syringe services programs (SSPs), and nonfatal overdose in the past 6 months. We identified three classes of current drug use: infrequent use (76% of participants), prescription drug use (12%), and heroin and/or cocaine injection (12%). PWID in the heroin and/or cocaine injection and prescription drug use classes had higher odds of both overdose and sharing syringes (relative to infrequent use). PWID in the prescription drug use class were 64% less likely to obtain syringes through SSPs/pharmacies relative to heroin and/or cocaine injection. Harm reduction programs need to engage people who obtain prescription drugs illicitly.