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

Abstract

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.

Keywords: harm reduction; latent class analysis; overdose; people who inject drugs; syringe sharing.

Figure 1

Latent Classes of Drug Use among Current and Former People who Inject Drugs in Baltimore, MD, 2017 We interpreted item response probabilities for a 3-class model of drug use to characterize the predominant drug use typologies among participants in the ALIVE study during 2017. Most participants (76.3%) were assigned to an infrequent drug use class. All participants in the infrequent use class used ≤5 total substances and tended to use

Figure 2

Associations of Drug Use Class with Overdose, Syringe Sharing, and Obtaining Syringes among 671 Current and Former People who Inject Drugs in Baltimore, MD, 2017 We examined how membership in the heroin and/or cocaine injection (top) and prescription drug use classes (middle) was associated with three outcomes relative to infrequent use: overdose, syringe sharing (among 431 participants who injected drugs in the past 6 months), and obtaining syringes from the Baltimore City Needle Exchange Program (BCNEP) or a pharmacy (among 431 participants who injected drugs in the past 6 months) using logistic regression. We also compared prescription drug use with heroin and/or cocaine injection (bottom). Adjusted results present the association of class with outcomes after adjustment for age, African American race, gender, homelessness, HIV (status and viral load detectability), depression, and alcohol use. Participants in the prescription drug use class had elevated odds of overdose and sharing syringes, but not of obtaining syringes compared to participants in the infrequent use class. Participants in the heroin and/or cocaine injection classes had higher odds of overdose, sharing syringes, and obtaining syringes relative to participants in the infrequent use class. Participants in the prescription drug use class were less likely to obtain syringes relative to participants in the heroin and/or cocaine injection class.