Crystal methamphetamine use subgroups and associated addiction care access and overdose risk in a Canadian urban...

Methamphetamine use is rising globally and we have limited treatments for this. Subgroups within the diverse methamphetamine-using population may have distinct treatment needs. Among a community-recruited sample of people who use crystal methamphetamine, we aimed to identify subgroups and characterize their overdose risk and access to addiction care.

Data from prospective cohorts of people who use drugs in Vancouver, Canada from 2014 to 2018 were used to conduct a repeated measures latent class analysis among participants who used crystal methamphetamine. Multivariable generalized estimating equations models were fit to determine the associated factors.

Among 824 eligible participants, a five-class model was identified as the best fit: (1) primary stimulant use (15.7%); (2) women engaged in sex work and opioid use (21.4%); (3) street income generation and opioid use (31.6%); (4) opioid agonist therapy (OAT) patients (22.3%); and (5) men who have sex with men (9.0%). In multivariable analyses, compared to the primary stimulant use group, non-fatal overdose was positively associated with street income generation (adjusted odds ratio [AOR] = 1.49, 95% confidence interval [95% CI]=1.30-1.71), sex work (AOR = 1.38, 95% CI=1.20-1.59) and OAT (AOR = 1.22, 95% CI=1.06-1.41) subgroups; engagement in non-OAT addiction care was negatively associated with street income generation (AOR = 0.81, 95% CI=0.68-0.97) and sex work (AOR = 0.78, 95% CI=0.63-0.98) subgroups.

Socioeconomically marginalized subgroups with opioid and crystal methamphetamine co-use were at highest risk of non-fatal overdose and had poorer access to addiction care, highlighting the need for tailored interventions.