RESUMO
INTRODUCTION: We sought to identify latent profiles of polysubstance use patterns among people who inject drugs in three distinct North American settings, and then determine whether profile membership was associated with providing injection initiation assistance to injection-naïve persons. METHODS: Cross-sectional data from three linked cohorts in Vancouver, Canada; Tijuana, Mexico; and San Diego, USA were used to conduct separate latent profile analyses based on recent (i.e., past 6 months) injection and non-injection drug use frequency. We then assessed the association between polysubstance use patterns and recent injection initiation assistance provision using logistic regression analyses. RESULTS: A 6-class model for Vancouver participants, a 4-class model for Tijuana participants and a 4-class model for San Diego participants were selected based on statistical indices of fit and interpretability. In all settings, at least one profile included high-frequency polysubstance use of crystal methamphetamine and heroin. In Vancouver, several profiles were associated with a greater likelihood of providing recent injection initiation assistance compared to the referent profile (low-frequency use of all drugs) in unadjusted and adjusted analyses, however, the inclusion of latent profile membership in the multivariable model did not significantly improve model fit. DISCUSSION AND CONCLUSIONS: We identified commonalities and differences in polysubstance use patterns among people who inject drugs in three settings disproportionately impacted by injection drug use. Our results also suggest that other factors may be of greater priority when tailoring interventions to reduce the incidence of injection initiation. These findings can aid in efforts to identify and support specific higher-risk subpopulations of people who inject drugs.
Assuntos
Usuários de Drogas , Abuso de Substâncias por Via Intravenosa , Transtornos Relacionados ao Uso de Substâncias , Humanos , Abuso de Substâncias por Via Intravenosa/epidemiologia , Estudos Transversais , México/epidemiologiaRESUMO
BACKGROUND: Opioid agonist treatment (OAT) is an effective biomedical intervention to manage opioid use disorder among persons who inject drugs (PWID). Preliminary evidence suggests that OAT may also disrupt the social communicability of injection drug use (IDU) practices by established PWID. We therefore aim to investigate the association between OAT enrollment and initiating others into IDU among PWID in Vancouver, Canada. METHODS: Preventing Injecting by Modifying Existing Responses (PRIMER; NIDA DP2-DA040256-01) is a prospective multi-cohort study seeking to identify structural interventions that reduce the risk that PWID initiate others into IDU. The present analysis was conducted using data from a participating cohort of PWID in Vancouver, Canada, between December 2014 and May 2017. Multivariable logistic regression models were built to assess the association between reporting active (i.e., within the past six months) OAT enrollment and assisting others in injection initiation. A final model was determined using a manual stepwise approach whereby covariates were excluded if their removal altered the coefficient of interest by <5%. RESULTS: Participants (n = 1740) were predominantly male (62.3%); 35.1% reported daily injecting (n = 611); 860 (49.4%) reported active OAT enrollment, and 80 (4.6%) reported recently providing injection initiation assistance. In a multivariable model, participants who reported active OAT enrollment had significantly lower odds of recently providing injection initiation assistance (Adjusted Odds Ratio = 0.52, 95% Confidence Interval: 0.31-0.87, P = 0.01). CONCLUSION: Results suggest a protective association between OAT and the expansion of IDU practices among vulnerable populations, suggesting its potential use as 'addiction treatment as prevention.'
Assuntos
Analgésicos Opioides/uso terapêutico , Tratamento de Substituição de Opiáceos/psicologia , Tratamento de Substituição de Opiáceos/estatística & dados numéricos , Transtornos Relacionados ao Uso de Opioides/psicologia , Abuso de Substâncias por Via Intravenosa/prevenção & controle , Adulto , Canadá , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Estudos Prospectivos , Abuso de Substâncias por Via Intravenosa/psicologiaRESUMO
Although most people who inject drugs (PWID) report receiving assistance during injection initiation events, little research has focused on risk factors among PWID for providing injection initiation assistance. We therefore sought to determine the influence of non-injection drug use among PWID on their risk to initiate others. We used generalized estimating equation (GEE) models on longitudinal data among a prospective cohort of PWID in Tijuana, Mexico (Proyecto El Cuete IV), while controlling for potential confounders. At baseline, 534 participants provided data on injection initiation assistance. Overall, 14% reported ever initiating others, with 4% reporting this behavior recently (i.e., in the past 6 months). In a multivariable GEE model, recent non-injection drug use was independently associated with providing injection initiation assistance (adjusted odds ratio [AOR] = 2.42, 95% confidence interval [CI] = 1.39-4.20). Further, in subanalyses examining specific drug types, recent non-injection use of cocaine (AOR = 9.31, 95% CI = 3.98-21.78), heroin (AOR = 4.00, 95% CI = 1.88-8.54), and methamphetamine (AOR = 2.03, 95% CI = 1.16-3.55) were all significantly associated with reporting providing injection initiation assistance. Our findings may have important implications for the development of interventional approaches to reduce injection initiation and related harms. Further research is needed to validate findings and inform future approaches to preventing entry into drug injecting.