Cohort Of Injection Drug Users Research Articles

Characteristics of attrition within the SuperMIX cohort of people who inject drugs: a multiple event discrete-time survival analysis

BackgroundCompared to the general population, people who inject drugs have poor health and wellbeing. Longitudinal studies can provide insight into factors driving these worse health outcomes but are subject to methodological challenges, such as cohort attrition. The aim of this study was to assess and characterise attrition in a prospective cohort of people who inject drugs in Victoria, Australia.MethodsUsing annually collected self-reported data from The Melbourne Injecting Drug User Cohort Study (SuperMIX) from September 2008 to January 2021, we estimated the incidence of participants being lost-to-follow-up (LTFU), with an episode of being LTFU defined as participants not undertaking a follow-up interview within two years of their last interview. We utilised a multiple event discrete-time survival analysis on participant period-observation data to estimate the associations between key factors and LTFU. Key areas of exposure measurement in analyses were sociodemographic, drug use and mental health.ResultsA total of n = 1328 SuperMIX participants completed a baseline interview, with n = 489 (36.8%) LTFU, i.e. not completing a follow-up interview in the following two years. Increased attrition was observed among SuperMIX participants who were: born outside Australia, younger than 30 years, reporting having completed fewer years of education, not residing in stable accommodation, not in stable employment and not on opioid agonist therapy (OAT).ConclusionsThe attrition rate of the SuperMIX cohort has largely been stable throughout the duration of the study. Higher attrition rates among individuals at greater sociodemographic disadvantage and not on OAT suggest that additional efforts are required to retain these participants. Findings also suggest that SuperMIX might not be capturing data on adverse health and wellbeing outcomes among subpopulations at high risk of harm.

Addiction habits in a rural cohort of injection drug users and effects on serum lipid profile: Analysis of a repeated measures study from an eastern state of India.

Background Injecting drug use (IDU) is associated with several cardiometabolic risks. We aimed to measure the independent effects of IDU behaviour and related factors on serum lipid profile among people who inject drugs (PWIDs). Methods We did a longitudinal study with six follow-up measurements at an interval of 2 months among 104 PWIDs from 11 selected hotspots under two blocks in West Bengal, India. Generalized estimating equations with robust standard errors analysed the effect of addiction habits on lipid profile parameters. Results The mean (SD) age of the participants was 27.6 (5.24) years, 36.5% married and 44.3% were unemployed at the time of recruitment. At the baseline, the mean (SD) body mass index (BMI) and fasting blood sugar (FBS) were 20.0 (1.82) kg/m2 and 112.0 (15.90) mg/dl, respectively. The mean duration of drug use was 2.5 (1.20) years. While 62.5% had normal triglyceride (TG), 14.4% had high total cholesterol (TC) and 69.2% had dyslipidaemia at the baseline. Adjusted for age, BMI, FBS and other addiction-related variables, models showed that longer duration of drug use (>3 years) resulted in higher levels of TG, higher TC-to-high-density lipoprotein ratio and dyslipidaemia. Tobacco use and high FBS level were also risk factors for dyslipidaemia. Conclusions Higher duration of IDU, tobacco use and higher FBS were associated with deranged lipid profile among PWIDs.

Injection Drug Use Frequency Before and After Take-Home Naloxone Training

Concerns that take-home naloxone (THN) training may lead to riskier drug use (as a form of overdose risk compensation) remain a substantial barrier to training implementation. However, there was limited good-quality evidence in a systematic review of the association between THN access and subsequent risk compensation behaviors. To assess whether THN training is associated with changes in overdose risk behaviors, indexed through injecting frequency, in a cohort of people who inject drugs. This cohort study used prospectively collected self-reported behavioral data before and after THN training of participants in The Melbourne Injecting Drug User Cohort Study (SuperMIX). Annual interviews were conducted in and around Melbourne, Victoria, Australia, from 2008 to 2021. SuperMIX participants were adults who regularly injected heroin or methamphetamine in the 6 months preceding their baseline interview. The current study included only people who inject drugs who reported THN training and had participated in at least 1 interview before THN training. In 2017, the SuperMIX baseline or follow-up survey began asking participants if and when they had received THN training. The first THN training date that was recorded was included as the exposure variable. Subsequent participant interviews were excluded from analysis. Injecting frequency was the primary outcome and was used as an indicator of overdose risk. Secondary outcomes were opioid injecting frequency, benzodiazepine use frequency, and the proportion of the time drugs were used alone. Fixed-effects generalized linear (Poisson) multilevel modeling was used to estimate the association between THN training and the primary and secondary outcomes. Time-varying covariates included housing status, income, time in study, recent opioid overdose, recent drug treatment, and needle and syringe coverage. Findings were expressed as incidence rate ratios (IRRs) with 95% CIs. There were 1328 participants (mean [SD] age, 32.4 [9.0] years; 893 men [67.2%]) who completed a baseline interview in the SuperMIX cohort, and 965 participants completed either a baseline or follow-up interview in or after 2017. Of these 965 participants, 390 (40.4%) reported THN training. A total of 189 people who inject drugs had pretraining participant interviews with data on injecting frequency and were included in the final analysis (mean [SD] number of interviews over the study period, 6.2 [2.2]). In fixed-effects regression analyses adjusted for covariates, there was no change in the frequency of injecting (IRR, 0.91; 95% CI, 0.69-1.20; P = .51), opioid injecting (IRR, 0.95; 95% CI, 0.74-1.23; P = .71), benzodiazepine use (IRR, 0.96; 95% CI, 0.69-1.33; P = .80), or the proportion of reported time of using drugs alone (IRR, 1.04; 95% CI, 0.86-1.26; P = .67) before and after THN training. This cohort study of people who inject drugs found no evidence of an increase in injecting frequency, along with other markers of overdose risk, after THN training and supply. The findings suggest that THN training should not be withheld because of concerns about risk compensation and that advocacy for availability and uptake of THN is required to address unprecedented opioid-associated mortality.

Comprehensive needle and syringe program and opioid agonist therapy reduce HIV and hepatitis c virus acquisition among people who inject drugs in different settings: A pooled analysis of emulated trials.

Although the Netherlands, Canada and Australia were early adopters of harm reduction for people who inject drugs (PWID), their respective HIV and hepatitis C (HCV) epidemics differ. We measured the pooled effect of needle and syringe program (NSP) and opioid agonist therapy (OAT) participation on HIV and HCV incidence in these settings. For each cohort, we emulated the design and statistical analysis of a target trial using observational data. We included PWID at risk of HIV or HCV infection from the Amsterdam Cohort Studies (1985-2013), Vancouver Injection Drug Users Study (1997-2009) and Melbourne Injecting Drug User Cohort Study (SuperMIX) (2010-2021). Separately for each infection and cohort (only HCV in SuperMIX), marginal structural models were used to compare the effect of comprehensive (on OAT and 100% NSP coverage or on OAT only if no recent injection drug use) versus no/partial NSP/OAT (no OAT and/or <100% NSP coverage) participation. Pooled hazard ratios (HR) and 95% CI were calculated using random-effects meta-analysis. We observed 94 HIV seroconversions and 81 HCV seroconversions among 2023 and 430 participants, respectively. Comprehensive NSP/OAT led to a 41% lower risk of HIV acquisition (pooled HR = 0.59, 95% CI = 0.36-0.96) and a 76% lower risk of HCV acquisition (pooled HR = 0.24, 95% CI = 0.11-0.51), compared with no/partial NSP/OAT, with little heterogeneity between studies for both infections (I2 = 0%). In the Netherlands, Canada and Australia, comprehensive needle and syringe program and opioid agonist therapy participation appears to substantially reduce HIV and hepatitis C acquisition compared with no or partial needle and syringe program/opioid agonist therapy participation. These findings from an emulated trial design reinforce the critical role of comprehensive access to harm reduction in optimizing infection prevention for people who inject drugs.

The association between depression and oral health related quality of life in people who inject drugs

Background and aimsOral health related quality of life (OHRQoL) is known to be reduced in disadvantaged populations, including people who inject drugs. Mental health issues, such as depression are also commonly reported. In this study we examined the association between depression and OHRQoL. MethodsCross-sectional analysis survey data was collected from the Melbourne Injecting Drug User Cohort Study (SuperMIX) of people who inject drugs (N = 982). Three measures derived from the Oral Health Impact Profile (OHIP-14) were used to assess OHRQoL: Prevalence (reporting one or more dental issue “Very often” or “Fairly often” in the previous year), Extent (number of items reported either “Very often” or “Fairly often”) and Severity (summary score of all ordinal responses). Regression analyses assessed the association between depression, indexed as scoring above 10 on the Patient Health Questionnaire (PHQ-9), and OHIP-14 measures, adjusted for sociodemographic, drug use and dental service utilisation variables. ResultsOverall, participants had low levels of OHRQoL, indexed through OHIP-14 scores (46% exhibiting prevalence, mean extent of 2.35 and mean severity of 12.72). Depression was associated with increases in all OHIP-14 measures, after adjustment for potential confounders. ConclusionsWe found a significant association between depression and poor OHRQoL in this sample of people who inject drugs. Further research using a longitudinal frame is needed to determine the direction of this relationship. Interventions to improve oral health of people who inject drugs are urgently needed, and these may benefit mental health outcomes for people who inject drugs.

The Melbourne Safe Injecting Room Attracted People Most in Need of Its Service

In 2018, the first Medically Supervised Injecting Room in Melbourne, Australia was officially opened. This study assessed whether this facility attracted people who inject drugs, who were socially vulnerable, and who engaged in drug-related behaviors associated with increased morbidity and mortality risk. This was a cross-sectional analysis of the frequency of Medically Supervised Injecting Room use during the first 18 months after opening (July 2018-December 2019) among 658 people who inject drugs participating in the Melbourne Injecting Drug User Cohort Study (SuperMIX). To examine the differences between no Medically Supervised Injecting Room use, infrequent use (<50% injections within the facility), and frequent use (≥50% of injections within the facility), RRRs were estimated using bivariate multinomial logistic regression analyses and postestimation Wald tests. Analyses were conducted in 2020. A total of 451 participants (68%) reported no Medically Supervised Injecting Room use, 142 (22%) reported infrequent use, and 65 (10%) reported frequent use. Participants who reported either infrequent or frequent use of the facility were more socially vulnerable (e.g., more often homeless) and more likely to report risky drug-related behaviors and poor health outcomes than those who reported no use. Participants who reported frequent use of the facility were also more likely to live close to the facility than those reporting infrequent use. The Melbourne Medically Supervised Injecting Room attracted socially marginalized people who inject drugs who are most at risk of harms related to injecting drug use and therefore who are most in need of the service. To determine the long-term impact use of this facility on key health outcomes such as overdose, future studies should consider the differences in vulnerability and risk behavior of people who inject drugs who use the Medically Supervised Injecting Room when examining the outcomes associated with the use of the facility.

Prevalence and correlates of simultaneous, multiple substance injection (co-injection) among people who inject drugs in Melbourne, Australia.

To estimate the prevalence of and risk factors associated with concurrent injection of multiple substances (co-injection) among a community-recruited cohort of people who inject drugs. Cross-sectional study. Melbourne, Australia. A sample of 720 actively injecting participants from the Melbourne Injecting Drug User Cohort Study (33% female) was extracted. We constructed two statistical models: a logistic regression model analysing correlates of co-injection of any substance combination in the past month and a multinomial logistic regression model analysing correlates of three mutually exclusive groups: heroin-diphenhydramine co-injection only, co-injection of other substances and no co-injection. Risk factors examined included drug use characteristics, demographic characteristics, health service use, hepatitis C status, injection risk behaviours and previous experience of non-fatal overdose. One-third [n = 226, 31%; 95% confidence interval (CI): 28-34%] of participants reported co-injecting substances within the past month, with equal numbers of participants reporting injecting combinations of heroin-diphenhydramine (n=121, 54%; 95% CI=48-60%) and heroin-methamphetamine (n=121, 54%; 95% CI=48-60%). In logistic regression analyses, reporting co-injection of any substance combination was associated with male sex [adjusted odds ratio (aOR)=1.80, 95% CI=1.18-2.74, P=0.006] and injecting daily or more frequently (aOR=2.04, 95% CI=1.31-3.18, P=0.002). In multinomial logistic regression analyses, participants reporting heroin-diphenhydramine co-injection only were significantly more likely to report groin injecting [adjusted relative risk ratio (aRRR)=6.16, 95% CI=2.80-13.56, P<0.001] and overdose (requiring an ambulance) in the past 12months (aRRR=2.81, 95% CI=1.17-6.72, P=0.021) compared with participants reporting no co-injection or co-injection of other substances. A substantial proportion of people who inject drugs report co-injection of multiple substances, which is associated with a range of socio-demographic, drug use and health service use risk factors.

Motivations for crystal methamphetamine-opioid co-injection/co-use amongst community-recruited people who inject drugs: a qualitative study

AimsWe report on motivations for crystal methamphetamine-opioid co-use/co-injection through narratives of people who inject drugs during a period of increased crystal methamphetamine use reporting in Australia.MethodsFourteen in-depth interviews were undertaken with selected participants (12 male, 2 female) from the Melbourne Injecting Drug User Cohort Study, including those in and out of opioid substitution therapy (OST).ResultsThe main motivations for co-use reported by participants were as follows: (1) that heroin could be used to reduce the negative side effects of heavy crystal methamphetamine use, particularly during the ‘comedown’ phase; (2) that small quantities of crystal methamphetamine used with heroin could prolong the intoxication effect of heroin, and hence the time before opioid withdrawal; (3) that co-injection of crystal methamphetamine and heroin produced a more desirable intoxication effect than using either substance on its own and; (4) that crystal methamphetamine provided a substitute ‘high’ for heroin after commencing OST treatment.ConclusionsCo-use of methamphetamine and opioids has been used by people who inject drugs to facilitate intoxication, sometimes as the result of ineffective opioid substitution therapy (OST) treatment and perceived lack of pleasure after stabilisation on OST treatment.

Follow-up of community injecting drug user cohort, 2014-2017

Objective: To explore the methods of establishing and maintaining community injecting drug user (IDU) cohort. Methods: From June 2014 to June 2017, a community survey was conducted on basis of local needle and syringe exchange site to recruit 200 HIV sero-negative IDU for a prospective cohort study in Longyang district of Baoshan city, Yunan province. Follow-up was carried out every six month to investigate high risk drug use behavior and sexual behavior, and blood samples were collected from them for the tests of HIV and HCV serum antibodies. The cohort would be opened every 12 months to replenish the cohort to 200 subjects. Results: The follow up was conducted for 3 years in 229 IDUs. Cohort follow-up rate was 93.0% (213/229) for 6 months, 92.1% (211/229) for 12 months, 91.7% (200/218) for 18 months, 87.2% (190/218) for 24 months, 86.0% (172/200) for 30 months and 86.0% (172/200) for 36 months. Conclusion: The community IDU cohort has a high follow-up rate.

Assessing individual-level needle and syringe coverage parameters and the measurement of coverage in Melbourne, Australia: methods and impacts.

To assess the structure of individual-level needle and syringe coverage measurement formula, and to estimate the impact of coverage-related behaviours/parameters (instances of syringe acquisition, total syringes acquired, peer-to-peer syringe distribution, injecting frequency) on overall coverage. Data are drawn from the Melbourne (Australia) injecting drug user cohort study, 2010-16. Data from 518 participants were analysed. We used correlations to explore the relationships between coverage parameters; pooled multiple-linear regression to estimate the effect of each parameter on coverage over time; and exploratory factor analysis to assess the relevance of each parameter within the coverage formula. A 1-unit increase in injecting frequency over time reduced coverage by 10.93 percentage points, almost twice as much as other coverage parameters. Factor analysis results indicated potential improvements to coverage formula structure. Our results suggest that reducing injecting frequency amongst people who inject drugs has the largest improvement in coverage levels, indicating harm reduction services should prioritize it. We also demonstrate that coverage measurement has been inconsistent to date. We sought to refine the method to assist in generating comparable research.

Differential Relationships among Circulating Inflammatory and Immune Activation Biomediators and Impact of Aging and Human Immunodeficiency Virus Infection in a Cohort of Injection Drug Users.

As individuals with human immunodeficiency virus (HIV) infection live longer, aging and age-related chronic conditions have become major health concerns for this vulnerable population. Substantial evidence suggests that chronic inflammation and immune activation contribute significantly to chronic conditions in people aging with or without HIV infection. As a result, increasing numbers of inflammation and immune activation biomediators have been measured. While very few studies describe their in vivo relationships, such studies can serve as an important and necessary initial step toward delineating the complex network of chronic inflammation and immune activation. In this study, we evaluated in vivo relationships between serum levels of neopterin, a biomediator of immune activation, and four commonly described inflammatory biomediators: soluble tumor necrosis factor (TNF)-α receptor (sTNFR)-1, sTNFR-2, interleukin (IL)-6, and C-reactive protein (CRP), as well as the impact of HIV infection and aging in the AIDS Linked to the Intravenous Experience (ALIVE) study, a community-recruited observational study of former and current injection drug users (IDUs) with or at high risk for HIV infection in Baltimore, MD, USA. The study included 1,178 participants in total with 316 HIV-infected (HV+) and 862 HIV-uninfected (HIV−) IDUs. Multivariate regression analyses were employed, adjusting for age, sex, body mass index, smoking, hepatitis C virus co-infection, injection drug use, comorbidities, and HIV status (for all participants), and HIV viral load, CD4+ T-cell counts, and antiretroviral therapy (for HIV+ participants). The results showed significant impact of aging on all five biomediators and that of HIV infection on all but sTNFR-1. In the adjusted model, neopterin had positive associations with sTNFR-1 and sTNFR-2 (partial correlation coefficients: 0.269 and 0.422, respectively, for all participants; 0.292 and 0.354 for HIV+; and 0.262 and 0.435 for HIV−, all p < 0.0001). No significant associations between neopterin and IL-6 or CRP were identified. Such differential relationships between circulating neopterin and sTNFR-1, sTNFR-2, IL-6, and CRP may help inform their selection in future studies. These findings may also facilitate elucidation of underlying inflammatory and immune activation pathways that contribute to age-related chronic conditions, potentially leading to identification of key biomediators, particularly those upstream of CRP, as novel targets for intervention.

\u201cJust not all ice users do that\u201d: investigating perceptions and potential harms of Australia\u2019s Ice Destroys Lives campaign in two studies

BackgroundIn 2015, the Australian government launched the media campaign Ice Destroys Lives targeting crystal methamphetamine use. Previous research indicates mass media campaigns may have harmful effects for people engaged in drug use. This study investigated perceptions and harms of Ice Destroys Lives among adults with a history of injecting drugs and young people.MethodsThis analysis includes data from two studies: an online questionnaire with young people and in-depth interviews with adults who use crystal methamphetamine. Young people from Victoria, Australia, were recruited through Facebook. We collected data on drug use, campaign recognition and behaviours. Participants who recognised the campaign indicated whether they agreed with five statements related to Ice Destroys Lives. We compared campaign perceptions between young people who reported ever using crystal methamphetamine and those who did not. Adults who use crystal methamphetamine were sampled from the Melbourne injecting drug user cohort study. We asked participants if they recognised the campaign and whether it represented their experiences.ResultsOne thousand twenty-nine young people completed the questionnaire; 71% were female, 4% had used crystal methamphetamine and 69% recognised Ice Destroys Lives. Three quarters agreed the campaign made them not want to use ice. Ever using crystal methamphetamine was associated with disagreeing with three statements including this campaign makes you not want to use ice (adjusted odds ratio (AOR) = 4.3, confidence interval (CI) = 1.8–10.0), this campaign accurately portrays the risks of ice use (AOR = 3.2, CI = 1.4–7.6) and this campaign makes you think that people who use ice are dangerous (AOR = 6.6, CI = 2.2–19.8). We interviewed 14 people who used crystal methamphetamine; most were male, aged 29–39 years, and most recognised the campaign. Participants believed Ice Destroys Lives misrepresented their experiences and exaggerated “the nasty side” of drug use. Participants felt the campaign exacerbated negative labels and portrayed people who use crystal methamphetamine as “violent” and “crazy”.ConclusionIn our study, Ice Destroys Lives was widely recognised and delivered a prevention message to young people. However, for people with a history of crystal methamphetamine use, the campaign also reinforced negative stereotypes and did not encourage help seeking. Alternative evidence-based strategies are required to reduce crystal methamphetamine-related harms.

HIV incidence and behavioral correlates of HIV acquisition in a cohort of injection drug users in St Petersburg, Russia

The aim of the project was to study human immunodeficiency virus (HIV) incidence, sociodemographic and behavioral correlates of HIV acquisition among injection drug users (IDUs).A total of 717 IDUs were recruited, tested, and counseled for HIV-1; 466 HIV-negative participants were enrolled and followed-up at 6 and 12 months. Sociodemographic and behavioral data were collected during each study visit. The association of sociodemographic and behavioral factors to HIV-1 incidence was assessed.During the 9-month recruitment period, 717 IDUs were screened and 466 participants were enrolled. HIV-1 prevalence at baseline was 35%. Most enrolled subjects were young (median age 30), male (75%), injected heroin in the previous 3 months (86%), about 50% had shared syringes and other paraphernalia, and 44% had unprotected sex in the last month. The retention rate at the 12-month follow-up was 72% and the adjusted retention rate was 88%. The HIV incidence rate was 7.2/100 person-years. HIV incidence was significantly associated with specific drug risk behaviors, including injecting the mixture of heroin and psychostimulants, the frequency of injecting in groups with other people, and having more drug dealers.The St Petersburg IDUs cohort demonstrates one of the highest HIV incidence rates in the world. In 2004 to 2006, the HIV incidence was 4.5, in 2005 to 2007—19.6, and in 2008 to 2009—7.2/100 person-years. The peak of HIV epidemic among IDUs in St Petersburg, as determined by 3 independent cohort studies, was in 2006 to 2007. Interventions targeting IDUs with long experience of heroin injection and high levels of injection risk behaviors are urgently needed.

Longitudinal changes in psychological distress in a cohort of people who inject drugs in Melbourne, Australia

BackgroundPrevious research into psychological distress among people who inject drugs (PWID) is predominantly cross-sectional; we determined longitudinal predictors of change in psychological distress among a cohort of PWID. MethodWe examined Kessler Psychological Distress Scale (K10) scores from 564 PWID (66% male) enrolled in the Melbourne Injecting Drug User Cohort Study. Gender-stratified linear models with fixed effects for each participant were used to examine correlates of change in individual K10 scores. Further linear regressions of adjusted K10 scores were used to measure correlations between demographic variables. ResultsParticipants reported higher K10 scores (higher psychological distress) than the general Australian population (mean K10 scores 23.4 (95%CI 22.6–24.2) and 14.5 (95%CI 14.3–14.7) respectively). The cohort’s mean K10 score did not significantly differ over time, but individual variations were common. Women reported higher K10 scores than men (mean baseline K10 scores 25.2 (95%CI 23.9–26.6) and 22.4 (95%CI 21.5–23.3) respectively), however no significant differences remained after controlling for temporal factors. Key predictors of increases in K10 scores were being the victim of an assault in the past six months (P<0.001 for women and men) and intentionally overdosing in the past 12 months (P=.010 for women and P<0.001 for men). ConclusionsPWID experience higher levels of psychological distress than the general population. Temporal rather than individual factors may account for the higher levels of psychological distress reported among women. Interventions to reduce rates of assault and/or intentional overdose should be explored to reduce high levels of psychological distress among PWID.

How is methamphetamine typically purchased and used in Melbourne, Australia? Reports from a cohort of people who inject drugs

Background: Methamphetamine-related harms have been increasing in Melbourne, Australia, yet little is known of how users interact with the drug market. We describe methamphetamine purchases and use as reported by a Melbourne-based cohort of people who inject drugs (PWID).Methods: A total of 2862 interviews from 757 participants of the Melbourne Injecting Drug User Cohort Study between April 2008 and February 2015 were used to generate descriptive statistics for the: size, search time and setting (e.g. house, street) of methamphetamine purchases, and the percentage that were shared; and the time of day, time between purchasing and using and setting of methamphetamine use.Results: No meaningful differences were observed between the powder and crystal methamphetamine markets. The most frequently purchased amount of methamphetamine was $100 with much larger transactions common; however 42% of purchases were shared, most commonly 50/50 with a partner or friend. The median time to obtain methamphetamine was 20 minutes (interquartile range (IQR) 5–30 minutes) and the median time between purchasing and using methamphetamine was 5 minutes (IQR 5–10 minutes). Most purchases were used between 10 am and 2 pm (43% of purchases), but 33% were used outside of business hours. Both purchasing and using methamphetamine occurred more frequently in houses than public settings.Conclusions: It was common for PWID in our sample to obtain >$100 of methamphetamine with a partner or friend, with relatively little search time. Support services for methamphetamine users may need to increase their operating hours to adapt to the large amount of use occurring outside of business hours.

Mortality in the Melbourne injecting drug user cohort study (MIX).

BackgroundThere are few studies of mortality amongst people who inject drugs (PWID) in Australia. In this study, we estimate mortality in a cohort of PWID in Melbourne and examine predictors of mortality including health service use, demographic characteristics, drug use and personal wellbeing.FindingsWe linked identifiers from the Melbourne injecting drug use cohort study (MIX; n = 655) to the National Death Index from 2008 to 2012 to estimate standardised mortality ratios (SMRs). Cox regression was used to examine the bivariate relationship between exposures determined at baseline and subsequent mortality. There were 24 (3.6 %) deaths over the study period. The mortality rate in the cohort was 1.0 per 100 PY (95 % CI 0.71–1.57), with an SMR of 17.3 (95 % CI 11.6–25.8). Baseline reports of four or more lifetime incarcerations (HR 3.65, 95 % CI 1.16–11.52), past month ambulance attendance (HR 4.43, 95 % CI 1.76–11.17), past month emergency department presentation (HR 3.44, 95 % CI 1.47–8.03) and past 6-month self-reported heroin overdose (HR 3.14, 95 % CI 1.24–7.96) were associated with increased mortality risk.ConclusionsContact with emergency services, particularly for drug overdose, remains a lost opportunity to provide referrals for harm reduction and naloxone training programmes to PWID at greater risk of mortality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12954-015-0089-3) contains supplementary material, which is available to authorized users.

Associations of Circulating Soluble Tumor Necrosis Factor-α Receptors 1 and 2 with Interleukin-6 Levels in an Aging Cohort of Injection Drug Users with or at High Risk for HIV Infection.

Chronic inflammation marked by elevated interleukin (IL)-6, soluble tumor necrosis factor (TNF)-α receptor (sTNFR)-1, and sTNFR-2 levels may play a detrimental role in aging and HIV infection. This study aimed to evaluate the relationships of circulating IL-6 with sTNFR-1 and sTNFR-2 levels in an aging cohort of injection drug users (IDUs) with or at high risk for HIV infection. The AIDS Linked to the Intravenous Experience (ALIVE) study is a community-recruited, prospective observational study of former and current IDUs in Baltimore, Maryland. Serum IL-6, sTNFR-1, and sTNFR-2 levels were measured using standard ELISA. Multivariate linear regression analysis was employed, adjusting for age, sex, HIV status, injection drug use, comorbidities, as well as HIV viral load, CD4 T cell counts, and antiretroviral therapy where appropriate. The analysis included 1,178 participants (316 HIV positive and 862 HIV negative). In the adjusted model, sTNFR-1 and sTNFR-2 were individually associated with IL-6 (regression coefficient: 0.877 and 0.556, respectively, for all participants; 0.607 and 0.407 for HIV positives; and 0.999 and 0.628 for HIV negatives, all p < 0.0001). In the model combining sTNFR-1 and sTNFR-2, the associations for sTNFR-1 remained significant (0.693 for all participants, p < 0.0001; 0.417 for HIV positives, p < 0.05; and 0.840 for HIV negatives), while those for sTNFR-2 were no longer significant. sTNFR-1 and sTNFR-2 were positively associated with IL-6 in ALIVE participants. These findings provide initial insight into the in vivo relationship between TNF-α activation and IL-6 and a basis for further investigations into potential mechanisms underlying chronic inflammation in aging and HIV infection.

APSAD 2015 Conference, 8-11 November 2015, Perth, Western Australia.

Design and Methods: Participants were 757 PWID enrolled in the Melbourne Injecting Drug User Cohort Study. We used gender-stratified linear models with fixed effects for each participant to examine correlates of change in individual scores on the Personal Wellbeing Index (PWI) over time. Further linear regression of adjusted PWI scores was used to measure correlations between demographic variables.

Patterns of drug preference and use among people who inject drugs in Melbourne, Australia

Background: Understanding of substitution patterns in drug using careers is limited. Between 2009 and mid-2013, the purity-adjusted price of methamphetamine declined sharply in Melbourne in absolute terms and relative to the purity-adjusted price of heroin. We determine whether there were associated increases among people who inject drugs (PWID) in (1) use of methamphetamine and (2) citing methamphetamine as the drug of choice. Method: Responses to “drug of choice” and “most used drug” were obtained from baseline and follow-up interviews of the 688 PWID enrolled in the Melbourne Injecting Drug User Cohort Study between April 2008 and August 2013, categorised as heroin, methamphetamine, cannabis or other. Previous month heroin and methamphetamine use was reported at baseline by 82% and 41% of participants, respectively, and 51% had completed four or more interviews in this period. A Markov model that included marginal effects for methamphetamine purity-adjusted price was used to calculate (1) transitions between drug of choice and (2) conditional probabilities for most used drug. Parameters were determined by fitting multinomial logistic models to appropriate data subsets. Results: At baseline, the majority of participants reported heroin as both their preferred drug and the drug they used most. There were no significant increases in reports of methamphetamine as drug of choice, or as the most used drug. Conclusion: In a cohort of PWID who reported a range of drug behaviours, there was little evidence of drug substitution into methamphetamine, despite substantial declines in its purity-adjusted price.

Prescription opioid use and non-fatal overdose in a cohort of injection drug users

Background: There is growing concern regarding rising rates of prescription drug-related deaths among the general North American population as well as increasing availability of illicitly obtained prescription opioids. Concurrently among people who inject drugs (IDU), illicit prescription opioid use has increased while non-fatal overdose remains a major source of morbidity. Objectives: To evaluate whether the use of prescription opioids was associated with non-fatal overdose among IDU in Vancouver, Canada. Methods: Data was obtained from two open prospective cohorts of IDU between December 2005 and May 2013. We used generalized estimating equation (GEE) logistic regression to evaluate the association between prescription opioid use and non-fatal overdose, adjusting for various social, demographic, and behavioral factors. Results: There were 1614 IDU, including 541 (33.5%) women, who were recruited and included in this analysis. At baseline, 526 (32.6%) reported using prescription opioids and 118 (7.3%) reported experiencing an overdose in the previous six months. In a multivariable analysis, prescription opioid use remained independently associated with non-fatal overdose (adjusted odds ratio: 1.61, 95% confidence interval: 1.32–1.95), after adjusting for confounders. Conclusion: We observed relatively high rates of prescription opioid use among IDU in this setting, and found an independent association between prescription opioid use and non-fatal overdose. Our data is likely representative of riskier substance use associated with those who use prescription opioids within our sample. Interventions to prevent and respond to overdoses should consider the higher risk profiles of IDU who use prescription opioids.