Estimating injection drug use prevalence using state wide administrative data sources: Estonia, 2004

Estonia has rapidly expanding injection drug use (IDU) driven HIV/AIDS epidemic with the highest reported incidence rate and prevalence (1.3%) of HIV in the European region. To evaluate the feasibility of IDU prevalence estimations based on routine nationwide data sources using capture-recapture methodology, and provide estimates of IDU prevalence. IDUs were identified from the Police, Health insurance fund, State HIV reference laboratory data sources. Poisson regression models were fitted to the observed data, with interactions between data sources fitted to replicate ‘dependencies’ between the data sources. There were 13,886 (95% CI 8132–34,443) IDUs in Estonia in 2004, which translates into a prevalence of 2.4% (95% CI 1.4–5.9%) among people aged 15–44 years. The estimate is in line with the estimate provided by the panel of experts and estimates from the neighbouring countries experiencing similar societal and economic challenges.     

The pitfalls of prevalence estimation: the case of regular and dependent methamphetamine use in Australia

Objectives: The prevalence of regular and dependent methamphetamine use in Australia in 2013/14 was recently estimated indirectly using multipliers at 268,000 regular (defined as >monthly use in the past 6?months) and 160,000 dependent (defined as >3 on the Severity of Dependence Scale) methamphetamine consumers, respectively. We replicated this approach using more contemporary multipliers and alternate data sources to explore identified limitations with this approach.

Design: Two multipliers were derived from surveys of methamphetamine consumption in Sydney (NSW) in 2003/04 (the original multiplier) and Melbourne (VIC) in 2010 (a more contemporary multiplier), and applied to the time series of treatment utilisation figures for NSW and VIC, along with ABS-estimated resident population figures.

Results: Using the more contemporary VIC multiplier, we estimated numbers of regular (67,250, 95% CI?=?50,312-91,635) and dependent (43,232, 95% CI?=?34,477-57,947) methamphetamine users for Australia in 2013/14. This is approximately one-third of the figures reported previously. Our national estimates using the 2003/04 NSW multiplier applied to NSW treatment data (175,452, 95% CI?=?124,514-256,575 for regular, and 103,761, 95% CI?=?73,576-154,699 dependent, methamphetamine users respectively) are approximately two-thirds of the figures reported previously.

Conclusions: We urge caution in using treatment multipliers to estimate the prevalence of illicit drug use, particularly during periods of dramatic changes in treatment system capacity, user behaviour, drug purity and policing practices.     

Estimating the Number of Drug Injectors from Needle Exchange Data

Background. Information on the size of a drug injecting population is required for resource allocation and health service evaluation. The truncated Poisson (tP) estimator is a method of prevalence estimation which, in contrast to the capture-recapture method, can be used when only a single data source is available. Objective. We present a study on the size of a drug injecting population to illustrate how the tP estimator can be calculated and how some of its underlying assumptions can be checked. Results. Although 647 individuals attended the needle exchange in 1997, the total number of drug injectors was estimated to be 1041 within a 95% confidence interval of 960 ～ 1137. Discussion. The truncated Poisson estimator can be an easy and quick method of providing a prevalence estimate of drug injecting and may produce valid estimates of relative changes in prevalence rates over time.     

Estimating the prevalence,incidence and cessation of injecting drug use in Glasgow 1960–2000: Combining expert opinion with capture–recapture prevalence data

Estimation of and trends in the size of injecting drug user (IDU) populations is fundamental to the planning and development of health-care services for this group. In Glasgow, log–linear modelling of capture–recapture data estimated 8490 (95% CI 7490–9720) and 7190 (6090–8620) current IDUs in 1990 and 2000, respectively. Hitherto, however, no consensus had been sought on the size and shape of its IDU epidemic curve. A modified Delphi approach was used to elicit one for Glasgow. Twelve experts were asked to provide their opinion on the prevalence, incidence and cessation of injecting for quinquennia during 1960–2000. Instead of the usual iterative process to refine experts’ consensus, the elicitation of IDU incidence and cessation provided an opportunity, not previously explored, to combine these data and examine coherence with capture–recapture IDU prevalence estimates. Scrutiny of consensus data indicated that experts had underestimated incidence during 1985–1990, and overestimated prevalence during 1995–2000 and cessation during 1985–2000. Coherent median estimates indicated that prevalence (149–557), incidence (28–49) and cessation (1–2%) remained low and stable during 1960–1975, rose steeply between 1975 and 1990 (prevalence from 557 to 8238; incidence from 49 to 1375; cessation from 2 to 10%), and by 2000 there had been a decline in prevalence (6809) and incidence (1195) but a further rise in cessation (15%). Prevalence estimates from capture–recapture studies were essential to anchor experts’ consensus and derive coherent data. Further efforts are required to collect data which allow accurate estimation of the incidence and cessation of IDU.     

Estimating the Prevalence of Crack Dependence Using Capture-Recapture With Institutional and Field Data: A Three-City Study in the Netherlands

The aim of this study was to estimate the prevalence of crack dependence in the three largest Dutch cities (Amsterdam, Rotterdam, The Hague), stratified by gender and age. Three-sample capture-recapture, using data (collected between 2009 and 2011) from low threshold substitution treatment (n = 1,764), user rooms (n = 546), and a respondent-driven sample (n = 549), and applying log-linear modeling (covariates: gender, age, and city), provided a prevalence rate of 0.51% (95% CI: 0.46%–0.60%) for the population aged 15–64 years, with similar estimates for the three cities. Females (23.0% of total estimate) and younger crack users (12.8% aged <35 years) might be underrepresented in drug user treatment services.     

Problematic drug use and drug use disorders in EU countries and Norway: an overview of the epidemiology.

OBJECTIVE: To estimate the prevalence of drug use disorders in the European Union and Norway. METHOD: Based on a systematic literature search and an expert survey, publications after 1990 on prevalence of drug use disorders (DUD, defined as drug dependence and drug abuse or harmful use) in EU countries and Norway were reviewed. The search included both direct estimations based on general population surveys using the DSM-IIIR, DSM-IV, or ICD-10 definitions of DUD; and indirect estimates based on other epidemiological methods, such as multiplier procedures based on treatment or legal data and capture-recapture techniques. The indirect methods did not use diagnostic criteria, but criteria based on duration and pattern of use, labelled as problematic drug use as a meaningful approximation. RESULTS: The majority of DUD as estimated from direct methods using general population surveys were cannabis use disorders, usually not included in indirect estimates. The prevalence of thus defined disorders can be as high as 3%. For disorders other than cannabis use disorders (i.e. opioid, cocaine and amphetamine use disorders), indirect estimates of prevalence were consistently higher than those based on direct estimates, and ranged between 0.3% and 0.9% in European Union countries and Norway. Men have higher prevalence rates of DUD than women, but the difference was much less pronounced in general population surveys. Younger age (18-25 years) is the age group with the highest estimates. CONCLUSION: General population surveys typically result in a serious underestimation of the prevalence of DUD other than cannabis use disorders, because many people with DUD are not reached by these surveys (hidden populations). Based on the more valid indirect estimates, it is concluded that problem drug use constitutes a relatively high burden of disease and social problems in Europe.     

Childhood misbehavior and the risk of injecting drug use

This investigation examined the association between misbehavior in early life and subsequent injecting drug use (IDU) among Baltimore participants in the NIMH Epidemiologic Catchment Area study. Information about early misbehavior was collected in 1981 and about IDU in 1994–1996. Conditional logistic regression models were used to estimate the degree of association between early misbehavior and IDU, with injecting drug users (n=38) and controls matched on census tract of residence (n=745), selected from within the same community survey sample, and assessed in a methodologically identical manner. Early misbehavior was associated with subsequent IDU, independent of the associations with sex, age, and race. The estimated risk of IDU increased with the number of reported conduct problems. Early misbehavior also discriminated between injecting drug users and non-injecting drug users. These results, which support and extend earlier findings, have public health implications for preventing and stopping the risk-laden practice of injecting drug use.     

Poor criterion validity of self‐reported hepatitis B infection and vaccination status among injecting drug users: A review

Issues. Limited resources may dictate the use of self‐reported hepatitis B virus (HBV) status to determine the need for testing and/or vaccination in resource‐poor settings, as well as in research and surveillance. Approach. A synthesis of the literature on the criterion validity of self‐reported HBV infection and vaccination history among injecting drug users (IDU) in order to determine the utility or otherwise of self‐reports in this area. Key Findings. The degree of agreement between self‐reported and serological HBV status is consistently poor among IDU. In previous research, 46–95% of IDU with serological evidence of exposure to HBV did not report a history of infection, and serological evidence of vaccine‐conferred immunity was not detected among 50–73% of IDU who reported being vaccinated. Implications. A lack of awareness or misapprehension about their HBV status may lead some IDU to inadvertently engage in behaviours which place their injecting and sexual partners at risk, contributing to the continued potential for high incidence of HBV infection among this population. Conclusion. Self‐reported histories should not be used in lieu of serological testing when assessing infection history or immunisation status. Poor criterion validity also indicates that self‐reports of HBV infection status should not be used to estimate the prevalence and incidence of this infection. Due to their low sensitivity, self‐reports of HBV infection should at best be considered only as a lower bound prevalence estimate.[Topp L, Day C, Dore GJ, Maher L. Poor criterion validity of self‐reported hepatitis B infection and vaccination status among injecting drug users: A review. Drug Alcohol Rev 2009]     

Groin injecting in the context of crack cocaine and homelessness: From ‘risk boundary’ to ‘acceptable risk’?

Drawing on data from recent surveys and pilot qualitative interviews among injecting drug users (IDUs) in England, we highlight the potential ‘normalisation’ of the use of the femoral vein (groin) as a site of injection. We estimate that 45% (428/952) of IDUs in English cities report groin injecting in the last 4 weeks, rising to over 50% in some areas. We also note transitions towards the injection of crack cocaine among poly drug injectors in some UK locations. We estimate that 40% (381/952) of IDUs in English cities report crack injection in the last 4 weeks, rising to over 70% in some cities. Findings from pilot qualitative interviews among homeless injectors in London are suggestive of groin injecting being situated as an ‘acceptable risk’. We emphasise the need for research to explore the potential interplay between unstable housing, groin injecting and crack injecting. We call for renewed emphasis within harm reduction interventions advising injectors how to maximise the health and longevity of arm and other peripheral veins, and for greater preparedness to advise known groin injectors how to minimise health risks associated with groin injecting.     

Benzodiazepine use and HIV risk-taking behaviour among injecting drug users.

This paper examines the prevalence of benzodiazepine use, and its relationship to other drug use and HIV risk-taking among a sample of 1245 injecting drug users (IDU). Approximately a third (36.6%) of the sample had used benzodiazepines during their last typical month of injecting. Benzodiazepine users had injected more frequently, injected more heroin and amphetamines, and had more poly-drug use than other IDU. They also had higher levels of HIV risk-taking, having shared injecting equipment more frequently and with more people. There were no differences between groups in number of sexual partners or condom use, although benzodiazepine users were more likely to have been paid for sex. The demographic and drug use variables indicate that benzodiazepine users are a more dysfunctional subgroup of IDU who require particular attention in HIV interventions.     

High HIV and hepatitis C prevalence amongst injecting drug users in Mauritius: findings from a population size estimation and respondent driven sampling survey

Background

Mauritius, an Indian Ocean Island nation of approximately 1,000,000 people, has a large number of injecting drug users (IDUs), many of whom are infected with HIV and HCV. Mauritius has been expanding harm reduction and HIV services based in the belief that HIV prevalence amongst IDUs is somewhere between 30 and 60% and the IDU population size is around 20,000. In 2009, the government of Mauritius conducted a survey to estimate the infection prevalence and risk factors and to estimate the population size of IDUs in order to more effectively expand programmes.

Methods

Men and women aged >15 years living in Mauritius and injecting illicit drugs in the past three months were recruited using respondent driven sampling (RDS). Consenting participants were interviewed about HIV-risk behaviours and tested for HIV, syphilis, HCV and HBV. Six multipliers were collected from service data and by the ‘unique identifier’ method in conjunction with the RDS survey. Proportions were calculated using the RDS analysis tool.

Results

511 IDUs enrolled in the survey; 61.2% reported injecting 2-3 times/day and 29.3% reported past month injection with a previously used needle. Amongst the 60% of IDUs who reported having sexual intercourse in the past three months, 39.5% did so with ≥2 partners. Almost all IDUs (98.1%) reported inconsistent condom use in the past 12 months. HIV prevalence was 47.4%, HCV 97.3%, HBV 9.0%, and syphilis 2.7%; 99.7% of those infected with HIV were also infected with HCV. Our population size estimates put the number of IDUs in Mauritius at around 9500, lower than previous estimates.

Conclusions

We observed high rates of HCV and HIV infection amongst IDUs in Mauritius. The scale up of targeted HCV and HIV prevention, care and treatment services for IDUs should be a high priority.     

The injection of methadone and benzodiazepines among Sydney injecting drug users 1996-2000: 5-year monitoring of trends from the Illicit Drug Reporting System

Trends in the injection of methadone and benzodiazepines by injecting drug users (IDU) recruited in Sydney for the Illicit Drug Reporting System over the period 1996-2000 were examined. A total of 788 IDU were interviewed over the 5-year period. The proportion of IDU reporting recent methadone injecting declined significantly over the study period, from a peak of 31% in 1997 to 13% in 2000. Unlike the injection of methadone, there was no significant difference between the proportions of IDU reporting recent benzodiazepine injecting over the study period, which ranged between 10% and 16%. A consistent minority (range 5-7%) of IDU reported having injected both methadone and benzodiazepines in all years of the study. There were no differences in the proportions of males and females reporting recent methadone or benzodiazepine injecting in any individual year. Both methadone and benzodiazepine injecting were independently associated with higher levels of injection-related health problems. Given the substantial harms associated with these practices, continued monitoring of their prevalence is warranted.     

A multi-centre rapid assessment of injecting drug use in India

In 1998, a series of five rapid situation assessments (RSA) of injecting drug use were undertaken by The Society for Service to Urban Poverty (SHARAN) covering the major Metropolitan cities of Mumbai, Chennai, Calcutta, Delhi and Imphal. The RSA determined the extent and patterns of injecting drug use (IDU), the available responses, current and planned interventions, and drug users' perceptions of injecting and sexual-related risk behaviour. The RSA was necessary as there are a lack of data on IDU in India. This has resulted in the denial of injecting drug use except for the north-eastern states by official sources, thereby affecting the inputs for IDU-related interventions. The draft assessment reports were disseminated though city workshops, held between April 1998 and January 1999. Local NGOs involved in drug treatment and HIV related interventions, government officials, and the relevant State AIDS Cells were invited to the workshops in order to contribute to final city assessment reports, so as to promote ownership and to enhance coverage. While the data obtained from the RSA were largely as anticipated, the outcome of the dissemination workshops was phenomenal.     

Differences in sexual behaviour and condom use among cocaine and opioid injectors in Santos, Toronto and London

This paper makes comparisons in the sexual risk behaviour of cocaine and opioid injecting drug users (IDUs) in the cities of Santos, Toronto and London. Using a standardised WHO Multi-City Study interview schedule, 6 months risk behaviour data were collected among 1204 community-recruited drug injectors in Santos (n=220), Toronto (n=479) and London (n=505). Statistically significant differences in patterns of drug injecting and sexual behaviour were found between the cities. Results show cocaine injection to be most likely in Santos and heroin injection to be most likely in London. Anonymous saliva samples show HlV-1 prevalence among IDUs to be significantly higher in Santos (60%) than in London (7.0%) or Toronto (4.5%). Santos IDUs also were statistically more likely than Toronto or London IDUs to report higher frequencies of penetrative sex with both primary and casual partners, sex in exchange for drugs or money, sex with same sex partners, anal sex with opposite sex partners, and lower levels of condom use. Santos IDUs also reported a higher average number of sexual partners (6.1) than IDUs in Toronto (3.7) or London (1.8). These findings show that sexual behaviour change among IDUs is needed most urgently in Santos, where rates of HlV-1 prevalence and casual partner change were highest and condom use lowest. Possible explanations for the observed behavioural differences include the impact of particular injected drugs on sexual activity/safety, and the impact of social and economic factors on risk behaviour. There is an absence of ‘social epidemiology’ in contemporary cross-national HIV research and this hinders the development of culturally appropriate interventions. Interventions, whether in developed or developing countries, not only need to promote changes in individual behaviour but also in the social and political environment.     

A cross-sectional study on prevalence of non-fatal drug overdose and associated risk characteristics among out-of-treatment injecting drug users in North Vietnam

In a community-based cross-sectional survey among out-of-treatment male opiate injecting drug users (IDU) aged 18-45, data on non-fatal overdose were collected using a semi-structured questionnaire. From August to September 2003, 299 IDU were recruited in two districts of Bac Ninh, a semi-urban province in North Vietnam. Prevalence of lifetime and recent non-fatal overdose were 43.5 and 83.1%, respectively. Logistic regression analyses showed associations between non-fatal overdose and younger age, unemployment, residence in the provincial township, frequency of injecting, injecting heroin mixed with valium, and history of drug treatment. While recognizing the limitations of this study, it is the first in Southeast Asia to report on prevalence of drug use-related overdose. Future research is recommended on occurrence of fatal overdose in this population.     

A Cross-Sectional Study on Prevalence of Non-Fatal Drug Overdose and Associated Risk Characteristics Among Out-of-Treatment Injecting Drug Users in North Vietnam

In a community-based cross-sectional survey among out-of-treatment male opiate injecting drug users (IDU) aged 18–45, data on non-fatal overdose were collected using a semi-structured questionnaire. From August to September 2003, 299 IDU were recruited in two districts of Bac Ninh, a semi-urban province in North Vietnam. Prevalence of lifetime and recent non-fatal overdose were 43.5 and 83.1%, respectively. Logistic regression analyses showed associations between non-fatal overdose and younger age, unemployment, residence in the provincial township, frequency of injecting, injecting heroin mixed with valium, and history of drug treatment. While recognizing the limitations of this study, it is the first in Southeast Asia to report on prevalence of drug use–related overdose. Future research is recommended on occurrence of fatal overdose in this population.     

Effectiveness of needle and syringe programmes for preventing HIV transmission

Objective: To examine the effectiveness of needle and syringe programmes (NSPs) in preventing HIV transmission among injecting drug users (IDUs).Methods: An ecological study design was used to determine change in HIV prevalence among injecting drug users between cities with and without NSPs. Several data sources, such as electronic journal databases, surveillance reports, websites, and index review of relevant journals, were used to identify studies of HIV seroprevalence among IDUs, and presence of NSPs. The rate of change in HIV prevalence was estimated by regression analysis.Results: There were 778 years of data from 99 cities globally included in the analysis. HIV prevalence decreased by 18.6% per annum in cities that introduce NSPs, and increased by 8.1% in cities that had never introduced NSPs (mean difference −24.7% [95% CI: −43.8, 0.5%], P=0.06). The mean difference was –33% when comparison was weighted to one over the variance of the regression estimator (29% decrease in cities with NSPs and 5% increase in cities without NSPs, P<0.001). When analysis was restricted to cities with first HIV seroprevalence less than 10%, the average annual change in seroprevalence was 18% lower in cities with NSPs (P=0.03).Conclusions: Despite the inherent limitations within an ecological study design, the study provides additional evidence that NSPs reduce transmission of HIV infection. The rapid spread of HIV among IDU populations and increasing rates of injecting in many countries calls for scaling up of NSPs as well as other harm reduction strategies.     

Public injecting and willingness to use a drug consumption room among needle exchange programme attendees in the UK

This study examines the prevalence of public injecting and willingness to use drug consumption rooms (DCRs) among UK needle exchange programme (NEP) attendees. Three hundred and one injecting drug users (IDUs) were surveyed using a brief questionnaire across five NEPs in London and Leeds between April and June 2005. Injection in a public place in the past week was reported by 55% of the sample and 84% reported willingness to use a DCR if it was available. Public injecting was positively associated with insecure housing (AOR=2.1, CI 1.2-3.5, p=0.009), unsafe needle and syringe disposal in the past month (AOR=3.6, CI 1.9-6.9, p<0.001) and willingness to use DCR (AOR=2.7, CI 1.3-5.4, p=0.006). Public injecting was negatively associated with being aged more than 30 years (AOR=0.4, CI 0.3-0.7, p=0.003) and living in close proximity (within 0.5 miles/0.8 km) of the usual place of drug purchase (AOR=0.6, CI 0.3-0.9, p=0.02). Our findings suggest that recent public injecting is prevalent among UK NEP attendees and the majority would be willing to use DCRs if available. It is also probable that if such services were located close to key drug markets they would engage vulnerable IDU sub-populations such as young people and the insecurely housed and reduce their levels of public injecting and unsafe needle/syringe disposal. Targeted pilot implementation of DCRs in the UK is recommended.     

Mortality among injecting drug users in Melbourne: a 16-year follow-up of the Victorian Injecting Cohort Study (VICS)

Multiple factors affect injecting drug-related mortality, many of which will vary over time and between jurisdictions. There are relatively few studies of mortality among injecting drug users (IDU) in Australia. We aimed to provide data comparable to those reported internationally on the rate of mortality among IDU in Australia. We retrospectively examined mortality among participants (N=220) from the first Australian cohort study of IDU by linking coded personal identifier records with a national death register. The overall mortality rate among those followed-up was 0.83 per 100 PY (95% CI, 0.56-1.21 per 100 PY). This rate is lower than those reported internationally but comparable to the limited Australian data from other cohorts of IDU. Mortality was higher among males, most common among those aged in their early thirties and drug-related mortality occurred typically after substantial injecting careers. Extensive experience of incarceration (>or=3 times) was associated with increased risk of mortality. These results suggest that rates of mortality among Australian IDU may be lower than those reported internationally, with low HIV prevalence and Australia's long-held harm reduction framework potentially contributing to this result. Further studies using defined cohorts followed over time are needed to examine long-term outcomes among IDU in Australia.     

The Role of Physician and Nurse Attitudes in the Health Care of Injecting Drug Users

In 2005, 60 health care workers were recruited through services that attract injecting drug users (IDUs) and asked to complete attitude measures regarding IDU clients. Mediation analyses indicated that conservative health care workers displayed more negative attitudes toward their IDU clients because they believe that injecting drug use is within the control of the IDU. Negative attitudes toward IDU clients, in turn, were associated with worry about IDU clients’ behavior in the clinic and with beliefs that IDU clients should disclose their hepatitis C status to their health care worker. Perceptions of controllability of drug use were also associated with the belief that IDU clients’ ailments were caused by their IDU status. The study's limitations are noted.