Latent classes of polydrug and polyroute use and associations with human immunodeficiency virus risk behaviours and overdose among people who inject drugs in Tijuana, Baja California, Mexico

Abstract

Introduction and Aims. Patterns of polydrug use among people who inject drugs (PWID) may be differentially associated with overdose and unique human immunodeficiency virus (HIV) risk factors. Subgroups of PWID in Tijuana, Mexico, were identified based on substances used, route of administration, frequency of use and co-injection indicators. Design and Methods. Participants were PWID residing in Tijuana age ≥18 years sampled from 2011 to 2012 who reported injecting an illicit substance in the past month (n = 735). Latent class analysis identified discrete classes of polydrug use characterised by 11 indicators of past 6 months substance use. Multinomial logistic regression examined class membership association with HIV risk behaviours, overdose and other covariates using an automated three-step procedure in MPLUS to account for classification error. Results. Participants were classified into five subgroups. Two polydrug and polyroute classes were defined by use of multiple substances through several routes of administration and were primarily distinguished from each other by cocaine use (class 1: 5%) or no cocaine use (class 2: 29%). The other classes consisted primarily of injectors: cocaine, methamphetamine and heroin injection (class 3: 4%); methamphetamine and heroin injection (class 4: 10%); and heroin injection (class 5: 52%). Compared with the heroin-only injection class, memberships in the two polydrug and polyroute use classes were independently associated with both HIV injection and sexual risk behaviours. Discussion and Conclusions. Substance use patterns among PWID in Tijuana are highly heterogeneous, and polydrug and polyroute users are a high-risk subgroup who may require more tailored prevention and treatment interventions. [Meacham MC, Roesch SC, Strathdee SA, Lindsay S, Gonzalez-Zuniga P, Gaines TL. Latent classes of polydrug and polyroute use and associations with human immunodeficiency virus risk behaviours and overdose among people who inject drugs in Tijuana, Baja California, Mexico. Drug Alcohol Rev 2017;00:000-000]

Non-injection Drug Use and Injection Initiation Assistance among People Who Inject Drugs in Tijuana, Mexico

“…Fourth, this study focused on the specific effects of the use of individual drugs by non-injection. We note that a study conducted recently by Meacham and colleagues in the same setting suggested that poly-drug and poly-route users may represent specific subgroups with an increased risk of engaging in HIV risk behaviors [48]. This may underline the need for future research studies to assess whether these subgroups are at greater risk of providing injection initiation assistance.…”

Modelling integrated antiretroviral treatment and harm reduction services on HIV and overdose among people who inject drugs in Tijuana, Mexico

“…However, our results in terms of proportions of overdoses averted should be robust to uncertainty in the absolute overdose rate. Fourth, we neglected polysubstance use, but 15% of PWID in Tijuana report injecting both opioids and stimulants, which could alter the effect of opioid agonist therapy [53]. We purposely limited opioid agonist therapy scale-up to 40% coverage among PWID to account for a proportion who may be ineligible.…”

Polydrug use among people who use opioids, national survey on drug use and health 2002 to 2017.

“…31,32 More recently, person-centered approaches such as latent class analysis (LCA) and latent profile analysis (LPA) have emerged in the literature. 19,[33][34][35][36][37] However, most of the studies that examine patterns of polydrug use limited the scope of the types of substances included (e.g., drinking behaviors, injection drugs, illicit drugs), with specific foci on different subpopulations, such as adolescents, people who inject drugs, chronic pain patients, etc.…”

“…Four major criteria were used to decide which substance use variables went into the LCA model: type of substance, route of administration, co-injection, and frequency of use. 33 From the LCA analysis, participants were classified into five subgroups 33 Additionally, the investigators found that the two polydrug and polyroute classes (i.e., Classes 1 and 2) were more likely to report HIV risk behaviors (e.g., unprotected sex, having two or more sexual partners, drug use before or during sex, etc.) when compared to those who predominantly injected heroin (i.e., Class 5).…”

“…Furthermore, Class 1 members were more likely than Class 5 members to report having had an overdose in the past six months [OR (p-value): 3.35 (0.01)]. 33 And while the overall population from which the sample is drawn is not comparable to the U.S. population, the study results are consistent with the idea that those who have a greater amount of polydrug use behaviors are more likely to report needle sharing and overdose risk. 99,100…”