Dataset Information

Trajectories of injection drug use among people who use drugs in Vancouver, Canada, 1996-2017: growth mixture modeling using data from prospective cohort studies.

ABSTRACT: BACKGROUND AND AIMS:Injection drug use patterns are known to change over time, although such long-term changes have not been well described. We sought to characterize longitudinal trajectories of injection drug use and identify associated factors. DESIGN:Data were derived from the Vancouver Injection Drug Users Study and AIDS Care Cohort to evaluate the Exposure to Survival Services study, two prospective cohorts involving people who inject drugs in Vancouver, Canada between 1996 and 2017. Growth mixture modeling was applied to identify distinct injection drug use trajectories. Multinomial logistic regression was used to identify baseline factors associated with each trajectory. SETTING:Canada. PARTICIPANTS:A total of 2057 participants who reported having used illicit drugs via injection in the past 6 months at the baseline visit were included in the study. The median time since first injection drug use at baseline was 14.8 years (quartile 1-quartile 3: 6.5-24.3). MEASUREMENTS:Information regarding self-reported injection drug use during the past 6 months was collected at baseline and semi-annually thereafter via interviewer-administered questionnaires. FINDINGS:Participants were followed for a median of 113.4 months (quartile 1-quartile 3: 63.4-161.7). Five trajectories were identified: persistent high frequency injection (507, 24.6%); high frequency injection with late decrease (374, 18.2%); gradual cessation (662, 32.2%); early cessation with late relapse (227, 11.0%); and early cessation (287, 14.0%). Factors found to be associated with distinct trajectories included: daily heroin injection, binge injection drug use, age, not being in a stable relationship and year of study enrollment. CONCLUSIONS:People who used drugs in Vancouver, Canada from 1996 to 2017 appeared to follow five drug use trajectories, ranging from persistent high frequency use to early cessation. Almost 25% of participants remained high-frequency injectors over the study period.

SUBMITTER: Dong H

PROVIDER: S-EPMC7498269 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Trajectories of injection drug use among people who use drugs in Vancouver, Canada, 1996-2017: growth mixture modeling using data from prospective cohort studies.

Dong Huiru H Hayashi Kanna K Singer Joel J Milloy Michael John MJ DeBeck Kora K Wood Evan E Kerr Thomas T

Addiction (Abingdon, England) 20190816 12

<h4>Background and aims</h4>Injection drug use patterns are known to change over time, although such long-term changes have not been well described. We sought to characterize longitudinal trajectories of injection drug use and identify associated factors.<h4>Design</h4>Data were derived from the Vancouver Injection Drug Users Study and AIDS Care Cohort to evaluate the Exposure to Survival Services study, two prospective cohorts involving people who inject drugs in Vancouver, Canada between 1996 ...[more]

PMID: 31328354

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Project description:BACKGROUND:People who inject drugs (PWID) experience elevated rates of premature mortality. Although previous studies have demonstrated the role of supervised injection facilities (SIFs) in reducing various harms associated with injection drug use, including accidental overdose death, the possible impact of SIF use on all-cause mortality is unknown. Therefore, we examined the relationship between frequent SIF use and all-cause mortality among PWID in Vancouver, Canada. METHODS AND FINDINGS:Data were derived from 2 prospective cohort studies of PWID in Vancouver, Canada, between December 2006 and June 2017. Every 6 months, participants completed questionnaires that elicited information regarding sociodemographic characteristics, substance use patterns, social-structural exposures, and use of health services including SIFs. These data were confidentially linked to the provincial vital statistics database to ascertain mortality rates and causes of death. We used multivariable extended Cox regression analyses to estimate the independent association between frequent (i.e., at least weekly) SIF use and all-cause mortality. Of 811 participants, 278 (34.3%) were women, and the median age was 39 years (IQR 33-46) at baseline. In total, 432 (53.3%) participants reported frequent SIF use at baseline, and 379 (46.7%) did not. At baseline, frequent SIF users were on average younger than nonfrequent users, and a higher proportion of frequent SIF users than nonfrequent users were unstably housed, resided in the Downtown Eastside neighbourhood, injected in public, had a recent non-fatal overdose, used prescription opioids at least daily, injected heroin at least daily, injected cocaine at least daily, and injected crystal methamphetamine at least daily. A lower proportion of frequent SIF users than nonfrequent users were HIV positive and enrolled in addiction treatment at baseline. The median duration of follow-up among study participants was 72 months (IQR 24-123). In total, 112 participants (13.8%) died during the study period, yielding a crude mortality rate of 22.7 (95% CI 18.7-27.4) deaths per 1,000 person-years. The median years of potential life lost per death was 34 (IQR 27-42) years. In a time-updated multivariable model, frequent SIF use was inversely associated with risk of all-cause mortality after adjusting for potential confounders, including age, sex, HIV seropositivity, unstable housing, at least daily cocaine injection, public injection, incarceration, enrolment in addiction treatment, and calendar year of interview (adjusted hazard ratio 0.46, 95% CI 0.26-0.80, p = 0.006). The main study limitations are the limited generalizability of findings due to non-random sampling, the potential for reporting biases due to reliance on some self-reported information, and the possibility that residual confounding influenced findings. CONCLUSIONS:We observed a high burden of premature mortality among a community-recruited cohort of PWID. Frequent SIF use was associated with a lower risk of death, independent of relevant confounders. These findings support efforts to enhance access to SIFs as a strategy to reduce mortality among PWID. Further analyses of individual-level data are needed to determine estimates of, and potential causal pathways underlying, associations between SIF use and specific causes of death.

Project description:BACKGROUND:Urban drug scenes are characterized by high prevalence of illicit drug dealing and use, violence and poverty, much of which is driven by the criminalization of people who use illicit drugs (PWUD) and the associated stigma. Despite significant public health needs, little is understood about patterns of moving into urban drug scenes among PWUD. Therefore, we sought to identify trajectories of residential mobility (hereafter 'mobility') among PWUD into the Downtown Eastside (DTES), an urban neighbourhood with an open drug scene in Vancouver, Canada, as well as characterize distinct trajectory groups among PWUD. METHODS:Data were derived from three prospective cohort studies of community-recruited PWUD in Vancouver between 2005 and 2016. We used latent class growth analysis (LCGA) to identify distinct patterns of moving into the DTES among participants residing outside of DTES at baseline. Multivariable multinomial logistic regression was used to determine baseline factors associated with each trajectory group. RESULTS:In total, 906 eligible participants (30.9% females) provided 9,317 observations. The LCGA assigned four trajectories: consistently living outside of DTES (52.8%); early move into DTES (11.9%); gradual move into DTES (19.5%); and move in then out (15.8%). Younger PWUD, those of Indigenous ancestry, those who were homeless or living in a single-room occupancy hotel (SRO), and those injecting drugs daily were more likely to move in then out of DTES (all p<0.05). Living in an SRO, daily injection drug use, and recent incarceration were also positively associated with early mobility (all p<0.05). CONCLUSIONS:Nearly half of the participants moved into the DTES. Younger PWUD and Indigenous peoples appeared to have particularly high mobility, as did those with markers of social-structural vulnerability and high intensity drug use. These findings indicate a need to tailor existing social and health services within the DTES and expand affordable housing options outside the DTES.

Project description:BACKGROUND:The illicit selling and use of cannabis is prevalent among marginalized people who use illicit drugs (PWUD). Given that participation in illicit drug markets has been previously associated with a range of health and social harms, we sought to examine the predictors of selling cannabis among PWUD in Vancouver, Canada, a setting with a de facto legalized cannabis market, on the eve of the planned implementation of legalized non-medical cannabis including measures to regulate the existing illicit market. METHODS:Multivariable generalized estimating equations (GEE) logistic regression was used to analyze longitudinal factors associated with selling illicit cannabis among three prospective cohorts of PWUD between September 2005 and May 2015. RESULTS:Among the 3258 participants included in this study, 328 (10.1%) reported selling illicit cannabis at baseline, and 46 (5.1%) initiated cannabis selling over the study period. In the multivariable analysis of the whole sample, factors significantly associated with selling cannabis included cannabis use (Adjusted Odds Ratio [AOR]?=?4.05), dealing other drugs (AOR?=?3.87), being male (AOR?=?1.83), experiencing violence (AOR?=?1.40), non-medical prescription opioid use (AOR?=?1.32), non-custodial involvement in the criminal justice system (AOR?=?1.31), being stopped by police (AOR?=?1.30), crack use (AOR?=?1.25), homelessness (AOR?=?1.23), age (AOR?=?0.96 per year) and participation in sex work (AOR?=?0.67) (all p?<?0.05). The subanalyses indicated that dealing drugs other than cannabis, cannabis use, and non-custodial involvement in the criminal justice system were the only factors significantly associated with selling cannabis in all four subgroups. CONCLUSION:These findings support existing evidence indicating that selling illicit cannabis is often a survival-driven strategy to support the basic needs and substance use of some PWUD. Our findings suggest jurisdictions with planned or impending cannabis legalization and regulation should consider the vulnerability of PWUD when seeking to eradicate illicit cannabis markets, for example, in setting criminal penalties for selling cannabis outside of regulatory frameworks.

Dataset Information

Trajectories of injection drug use among people who use drugs in Vancouver, Canada, 1996-2017: growth mixture modeling using data from prospective cohort studies.

Publications

Trajectories of injection drug use among people who use drugs in Vancouver, Canada, 1996-2017: growth mixture modeling using data from prospective cohort studies.

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