The rising prevalence of prescription opioid injection and its association with hepatitis C incidence among street-drug users

AIMS

  To examine trends in prescription opioid (PO) injection and to assess its association with hepatitis C virus (HCV) seroconversion among injection drug users (IDUs).

DESIGN

  Prospective cohort study.

SETTING

  Montreal, Canada.

PARTICIPANTS

  HCV-negative IDUs at baseline, reporting injection in the past month.

MEASUREMENTS

  Semi-annual visits included HCV antibody testing and an interview-administered questionnaire assessing risk behaviours. HCV incidence rate was calculated using the person-time method. Time-updated Cox regression models were conducted to examine predictors of HCV incidence.

FINDINGS

  The proportion of IDUs reporting PO injection increased from 21% to 75% between 2004 and 2009 (P < 0.001). Of the 246 participants (81.6% male; mean age 34.5 years; mean follow-up time 23 months), 83 seroconverted to HCV [incidence rate: 17.9 per 100 person-years; 95% confidence interval (CI) 14.3, 22.1]. Compared to non-PO injectors, PO injectors were more likely to become infected [adjusted hazard ratio (AHR): 1.87; 95%CI:1.16, 3.03]. An effect modification was also found: PO injectors who did not inject heroin were more likely to become infected (AHR: 2.88; 95%CI: 1.52, 5.45) whereas no association was found for participants using both drugs (AHR: 1.19; 95% CI: 0.61, 2.30). Other independent predictors of HCV incidence were: cocaine injection, recent incarceration and >30 injections per month.

CONCLUSIONS

  Prescription opioid injectors who do not inject heroin are at greater risk for HCV seroconversion than are those injecting both heroin and prescription opioids. Important differences in age, behaviour and social context suggest a need for targeted outreach strategies to this population.

GM130 gain-of-function induces cell pathology in a model of lysosomal storage disease

Cell pathology in lysosomal storage diseases is characterized by the formation of distended vacuoles with characteristics of lysosomes. Our previous studies in mucopolysaccharidosis type IIIB (MPSIIIB), a disease in which a genetic defect induces the accumulation of undigested heparan sulfate (HS) fragments, led to the hypothesis that abnormal lysosome formation was related to events occurring at the Golgi level. We reproduced the enzyme defect of MPSIIIB in HeLa cells using tetracycline-inducible expression of shRNAs directed against α-N-acetylglucosaminidase (NAGLU) and addressed this hypothesis. HeLa cells deprived of NAGLU accumulated abnormal lysosomes. The Golgi matrix protein GM130 was over-expressed. The cis- and medial-Golgi compartments were distended, elongated and formed circularized ribbons. The Golgi microtubule network was enlarged with increased amounts of AKAP450, a partner of GM130 controlling this network. GM130 down-regulation prevented pathology in HeLa cells deprived of NAGLU, whereas GM130 over-expression in control HeLa cells mimicked the pathology of deprived cells. We concluded that abnormal lysosomes forming in cells accumulating HS fragments were the consequence of GM130 gain-of-function and subsequent alterations of the Golgi ribbon architecture. These results indicate that GM130 functions are modulated by HS glycosaminoglycans and therefore possibly controlled by extracellular cues.

Residential trajectory and HIV high-risk behaviors among Montréal street youth--a reciprocal relationship

Evidence has linked residential instability and engagement in high-risk behaviors. This paper longitudinally examines the relationship between changes in residential stability and changes in HIV risk behaviors among Montréal street youth (SY). Between April 2006 and May 2007, 419 SY (18-25 years old) were recruited in a cohort study. SY (using Montréal street youth agencies services) were eligible if they had had at least one 24-hour episode of homelessness in the previous 30 days. Baseline and follow-up interviews, carried out every 3 months, included completion of a questionnaire (based on Life History Calendar Technique) assessing daily sleeping arrangements since the last interview, and monthly sexual and drug use behaviors. Using mixed-effects logistic regression method, we examined the association between various risk behaviors and residential stability, reached when a youth resided in any of the following settings for a whole month: own place; friends'/partner's/parent's place; any types of housing service (excluding emergency shelters). Analyses were carried out controlling for gender, age, education level, lifetime duration of homelessness, childhood sexual trauma, and lifetime mental health disorders. As of January 2009, 360 SY (79% boys) had completed at least one follow-up interview, representing 4,889 months of follow-up. Residential stability was significantly associated with the following: sex exchange (adjusted odd ratio [AOR], 0.25; 95% confidence interval [CI], 0.14-0.37), drug injection (AOR, 0.55; CI, 0.33-0.76), daily alcohol consumption (AOR, 0.58; CI, 0.42-0.74), polydrug consumption (AOR, 0.61; CI, 0.50-0.73), polydrug consumption excluding marijuana (AOR, 0.55; CI, 0.45-0.65), and multiple sex partners (≥3 partners; AOR, 0.57; CI, 0.40-0.74). Our results suggest a reciprocal relationship between residential instability and HIV risk behaviors. This calls for more integrated services combining both individual and structural-level interventions to improve the health of street youth.

Modeling neuronal defects associated with a lysosomal disorder using patient-derived induced pluripotent stem cells

By providing access to affected neurons, human induced pluripotent stem cells (iPSc) offer a unique opportunity to model human neurodegenerative diseases. We generated human iPSc from the skin fibroblasts of children with mucopolysaccharidosis type IIIB. In this fatal lysosomal storage disease, defective α-N-acetylglucosaminidase interrupts the degradation of heparan sulfate (HS) proteoglycans and induces cell disorders predominating in the central nervous system, causing relentless progression toward severe mental retardation. Partially digested proteoglycans, which affect fibroblast growth factor signaling, accumulated in patient cells. They impaired isolation of emerging iPSc unless exogenous supply of the missing enzyme cleared storage and restored cell proliferation. After several passages, patient iPSc starved of an exogenous enzyme continued to proliferate in the presence of fibroblast growth factor despite HS accumulation. Survival and neural differentiation of patient iPSc were comparable with unaffected controls. Whereas cell pathology was modest in floating neurosphere cultures, undifferentiated patient iPSc and their neuronal progeny expressed cell disorders consisting of storage vesicles and severe disorganization of Golgi ribbons associated with modified expression of the Golgi matrix protein GM130. Gene expression profiling in neural stem cells pointed to alterations of extracellular matrix constituents and cell-matrix interactions, whereas genes associated with lysosome or Golgi apparatus functions were downregulated. Taken together, these results suggest defective responses of patient undifferentiated stem cells and neurons to environmental cues, which possibly affect Golgi organization, cell migration and neuritogenesis. This could have potential consequences on post-natal neurological development, once HS proteoglycan accumulation becomes prominent in the affected child brain.

Drug use patterns in the presence of crack in downtown Montréal

INTRODUCTION AND AIMS

A study was undertaken to verify reports of an increasing presence of crack in downtown Montréal, and to investigate the influence of crack availability on current drug use patterns among street-based cocaine users.

DESIGN AND METHODS

The study combined both qualitative and quantitative methods. These included long-term intensive participant observation carried out by an ethnographer familiar with the field and a survey. The ethnographic component involved observations and unstructured interviews with 64 street-based cocaine users. Sampling was based on a combination of snowballing and purposeful recruitment methods. For the survey, structured interviews were conducted with a convenience sample of 387 cocaine users attending HIV/HCV prevention programs, downtown Montréal.

RESULTS

A gradual shift has occurred in the last 10 years, with the crack street market overtaking the powder cocaine street market. Although the data pointed to an increase in crack smoking, 54.5% of survey participants both smoked and injected cocaine. Drug market forces were major contributing factors to the observed modes of cocaine consumption. While the study focused primarily on cocaine users, it became apparent from the ethnographic fieldwork that prescription opioids (POs) were very present on the streets. According to the survey, 52.7% of participants consumed opioids, essentially POs, with 88% of them injecting these drugs.

DISCUSSION AND CONCLUSIONS

Despite the increased availability of crack, injection is still present among cocaine users due at least in part to the concurrent increasing popularity of POs.

Initiation to drug injection among street youth: a gender-based analysis

OBJECTIVE(S)

To estimate the incidence rate of initiation into drug injection and to identify predictors of initiation into drug injection separately among street girls and boys.

DESIGN

Data from two consecutive prospective street youth cohort studies (1995-2001 and 2001-2005) were used to conduct these analyses, stratified by gender.

METHODS

Data were collected using semi-annual interviewer-administered questionnaires. Variables from the following domains were considered in Cox regression models: socio-demographic characteristics, early and current substance abuse, marginalization, childhood traumatic sexual events and injection exposure.

RESULTS

Of the 946 youth who had never injected drugs at study entry, 86.4% completed at least two questionnaires representing 243 girls and 574 boys. Incidence rates of injection of 7.0 and 5.9 per 100 person-years were observed among these girls and boys respectively. Among girls, cocaine or crack use (adjusted hazard ratio (AHR)=1.97), heroin use (AHR=2.86), homelessness (AHR=2.49) and hanging out regularly with people who inject (AHR=4.46) all independently increased risk of first injection. Among boys, age decreased risk of initiating injection (AHR=0.90/year), while cocaine or crack use (AHR=2.14), heroin use (AHR=3.56), homelessness before age 16 (AHR=1.68), incest or rape before age 14 (AHR=1.98) and hanging out regularly with people who inject (AHR=1.66) all independently increased this risk.

CONCLUSIONS

Our findings suggest similar rates of initiation among girls and boys; however, factors associated with initiation vary by gender. This might lead to the design of more effective programs to prevent initiation into drug injection.

Modeling initiation into drug injection among street youth

This study aimed at examining the predictors of initiation into drug injection among street youth using social cognitive theory framework. A prospective cohort study based on semi-annual interviews was carried out. Psychosocial determinants referred to avoidance of initiation. Other potential predictors were: sociodemographic characteristics, relationships with injectors, parent's substance misuse, drug use patterns, homelessness, survival sex, sexual abuse. Independent predictors were identified using Cox proportional hazards regression models. Among the 352 participants, high control beliefs about avoidance of initiation was protective while younger age, daily alcohol consumption, heroin use, cocaine use, and survival sex all increased risk of initiation. Preventive strategies targeting street youth should both enhance youth's control beliefs and actual control over their substance use and improve their life conditions.

The growing popularity of prescription opioid injection in downtown Montréal: new challenges for harm reduction

Starting in 2007, a 2-year study based on ethnographic methodology was carried out downtown Montréal, Canada. A thematic analysis of observational and interview-based notes was conducted. Illicit prescription opioid (PO) use was widespread among street-based participants. Injection was the main mode of PO administration observed among users. Some injection practices such as "doing a wash" could pose new challenges in terms of prevention of infections. More research is needed to examine the role of illicit PO use in the development of opiate addiction and to better understand drug-using contexts that put PO users at risk of infections. The study's limitations are noted.

Predictors of crack cocaine initiation among Montréal street youth: a first look at the phenomenon

BACKGROUND

Crack cocaine use is increasing in Montréal. However, initiation risk factors among street youth are unknown. The goal of this project is to estimate the incidence of first crack cocaine use among these youth and to identify the associated risk factors.

METHODS

A prospective cohort study of HIV and hepatitis C incidence was conducted among street youth from 2001 to 2005. A questionnaire on sexual and drug use behaviours was administered every 6 months. Incidence was estimated (a) for youth who had never used crack cocaine at recruitment (n=203) and, among them, (b) for those who had snorted cocaine before (n=122). The risk factors for initiation of crack use as well for initiation into a new route of cocaine administration among youth who had snorted cocaine before were determined using Cox regression.

RESULTS

Incidence rates for crack cocaine use were (a) 136.6/1000 person-years (p-y) (95% confidence interval [CI]: 104.5-175.5) and (b) 205.8/1000 p-y (95% CI: 150.2-275.3). The number of substance types used recently increased the risk of initiating crack use (adjusted hazard ratio [AHR]=1.84 per substance type, 95% CI: 1.55-2.18), whereas having a parent with a substance abuse problem decreased that risk (AHR=0.48, 95% CI: 0.26-0.89). The risk factors were identical among youth who had snorted cocaine before.

CONCLUSIONS

Our analyses show a high incidence of crack use among street youth. It is important to delve more deeply into the phenomenon of initiation if we wish to develop effective prevention measures for these young people.

The challenge of understanding mortality changes among street youth

According to a cohort study conducted in Montréal, Québec from 1995 to 2000, the mortality rate among street youth was 921/100,000 person-years. Several new community initiatives aiming to increase access to housing and to social and health services for the homeless were implemented in the city between 2000 and 2003. This study aims to update the mortality rate estimate for the period 2001-2006 and to examine factors that could explain a difference between rates, if any. A second cohort study was conducted between 2001 and 2006. The Cohort 2 mortality rate was computed and compared with the Cohort 1 rate. Several analyses were then carried out: (1) mortality rates in the general population were compared with street youth rates using standardized mortality ratios (SMR); (2) Cohorts 1 and 2 distributions of risk factors for mortality were examined, and their effects were assessed using multivariate proportional hazards regression analyses carried out on a combined Cohorts 1 and 2 dataset. Mortality rate among street youth decreased by 79% while it declined by only 19% in the general population; the SMR for Cohort 1 was higher than for Cohort 2 (11.6 versus 3.0). Multivariate proportional hazards regression analyses yielded estimates that were close to the model's estimates based on Cohort 1 data only, and participation in Cohort 1 was an independent predictor of mortality, with an adjusted hazard ratio of 9.0. The mortality decline cannot be completely explained by a similar decrease among the general population or by a difference in distribution of risk factors for mortality between the two cohorts. Field workers suggested that the decrease in heroin consumption they had observed in the streets might have contributed to the mortality decline. We then performed additional analyses which showed that even though the proportion of street youth currently using heroin decreased significantly between 1995 and 2005, the association between heroin use and mortality was not significant (adjusted hazard ratio of 0.9; 95% CI, 0.4 to 2.3). It seems that various factors could have contributed to the decline in mortality rates among street youth, one plausible factor being the implementation of new services for the homeless. This study underscores the importance of monitoring risky behaviors among vulnerable populations to ensure that morbidity and mortality data among these populations is correctly interpreted. Setting up a system to monitor the drug market could improve the quality of information collected.

Hepatitis C virus incidence among young street-involved IDUs in relation to injection experience

BACKGROUND

Young injection drug users (IDUs) are at very high risk of hepatitis C virus (HCV) infection. Using a time scale starting at first injection, we studied the period of HCV susceptibility after initiation into drug injection among street-involved IDUs.

METHODS

A prospective cohort study was carried out among street youth from 2001 to 2005. Semiannual interviews included completion of an interviewer-administered questionnaire and collection of blood samples for HCV antibody testing. HCV-negative subjects currently injecting drugs (last six months) were included in the analyses. Follow-up started at first questionnaire where current injection was reported and ended at seroconversion or at last questionnaire. Poisson regression was used to assess the predictive power of time elapsed since initiation on incidence rate. Kaplan-Meier technique was used to estimate cumulative infection probabilities.

RESULTS

Among the 858 cohort participants, 145 were injecting at baseline and 60 were injecting at a subsequent questionnaire (45 youth had started injection and 15 had resumed injection). Mean age was 20 years and 62% were males. In the 395 person-years of follow-up, 61 subjects contracted HCV. The HCV incidence rate increased from 16.1/100 person-years during the first year following first injection to 22.4 in the third year, and then decreased to 7.2 in years 7-13 (p=0.02). Median time to seroconversion after first injection was 3.3 years.

CONCLUSION

The first years after first injection is the period during which vulnerability to HCV is greatest. Our results show the importance of intervening with new IDUs to optimize the chances to successfully prevent infection.

Access to sterile injecting equipment is more important than awareness of HCV status for injection risk behaviors among drug users

Awareness of hepatitis C virus (HCV) infection status is expected to influence risk behaviors. In 2004-2005, injection drug users (IDUs) recruited from syringe exchange programs (SEPs) and methadone clinics in Montreal, Canada, were interviewed on drug use behaviors (past 6 months) and HCV testing. Subjects (n = 230) were classified as low/intermediate risk (20.4% borrowed drug preparation equipment only) and high risk (19.6% borrowed syringes), and 54.5% reported being HCV positive. Logistic regression modeling showed that compared to no risk (60% borrowed nothing), low/intermediate risk was associated with fewer noninjecting social network members, poor physical health, and problems obtaining sterile injecting equipment. High risk was associated with all of these factors except social networks. HCV status was not associated with any level of risk. Improved access to sterile injecting equipment may be more important than knowledge of HCV status in reducing injection risks among this IDU population. The study limitations are noted and recommendations discussed.