Estimating the size of crack cocaine users in France: Methods for an elusive population with high heterogeneity

BackgroundDespite several sources corroborating an expanding market and increased visibility and greater diversity in users’ profiles, very little is known about the number of crack cocaine users in France.MethodThe estimates rely on a single data source capture–recapture method. Annual data are extracted from treatment centres nationwide. To account for heterogeneity, we use an innovative zero-truncated geometric, regression-based estimator controlling for individual and centre characteristics. We use the well-known Zelterman estimator as a benchmark.ResultsThe number of crack cocaine users received in treatment centres increased dramatically, from 3388 in 2010 to 5143 in 2017 (+52%). The estimated number of crack cocaine users is believed to have tripled over the course of the same period (from 9775, 95% CI [8288–11530] to 28983 [24876–33766], respectively), with prevalences below 1‰, similar to other European countries. The coverage rate (observed number/estimated number of users) decreased in a similar fashion, indicating lower utilization. In particular, females and younger users are underestimated by data from treatment centres.ConclusionThe prevalence of crack cocaine use is fairly low but steadily increasing. The diversity in users’ profiles is a challenge to prevention and public health policies that should expand their scope to a more inclusive perspective of what defines crack cocaine users. Our method overcomes several methodological issues (data sources, data linkage, heterogeneity) and can be easily applied to a wide range of settings.     

Estimating the Number of Heroin Users in Metropolitan France Using Treatment Centers Data: An Exploratory Analysis

Background: An updated prevalence estimate for heroin users in France is lacking. Accurate figures are needed to estimate the potential need for treatment. Method: This research relies on a capture-recapture framework and, for the first time, makes use of individual data collected by a standardized survey conducted within treatment centers. Taking the hierarchical structure of data collection into consideration, a multilevel Zelterman regression model was used, thus enabling estimates at national level. Results: The number of heroin users was estimated to be 76,000, 95% CI = [68,000; 85,000] in 2009 (prevalence of 1.9‰ [1.7–2.1]), 101,000 in 2011, 95% CI = [66,000–137,000] (prevalence of 2.5‰ [1.6–3.4]), and 107,000 in 2013, 95% CI = [85,000–124,000] (prevalence of 2.6‰ [2.1–3.1]), with a 4:1 ratio of male:female. Less than one heroin users out of three was seen in treatment centers in 2013. Conclusions: The rise in the number of heroin users is related to an increasing availability of heroin, increasing use in more remote areas, and providers targeting new types of users. The figures, however, should be completed with alternative estimates and enhance the need for a perennial monitoring.     

Capture–recapture estimates of the local and national prevalence of problem drug use in Scotland

Estimates of the prevalence of problem drug use, defined within this study as the illicit use of opiates or benzodiazepines, have been provided for all 32 local government areas in Scotland. A national prevalence estimate has been derived as the sum of the local estimates.Data on individual drug users were collated from the police, social work departments, general practitioners, drug treatment services. These data were augmented by the Scottish Drug Misuse Database. In total 22,795 individuals were identified as opiate or benzodiazepine users. This figure corresponds to 0.8% of the population aged 15 to 54.In terms of the national prevalence of problem drug use, it was estimated that there were 55,800 individuals illicitly using opiates and benzodiazepines in Scotland in the year 2000 (95% CI: 43,591–77,697%). That figure corresponds to 2.0% (95% CI: 1.5–2.7%) of the population aged 15 to 54. The local prevalence rates, derived from capture–recapture estimates, ranged from 0.8 to 3.8%.This study has demonstrated that it is possible to use the capture–recapture method in urban and rural areas and, by systematically applying this method at the local level, a national prevalence estimate can be obtained.     

Drug-Related Deaths in France in 2007: Estimates and Implications

Compared with other European countries, France's low number of drug use-related deaths may appear enviable. Previous studies have suggested significant underreporting. The three official records listing drug-related deaths in France in 2007 were cross-checked. Different capture–recapture techniques were applied. The estimated numbers of drug-related deaths differ from the official figures. Different explanations and proposals to improve the recordings are consequently discussed. However, there are doubts as to the reliability of at least one of the records and the consequent accuracy of the proportion of overlapping cases. Estimates should be handled with caution and interpreted as upper bounds.     

Estimates of the national trend of drugs use during 2000–2030 in China: A population-based mathematical model

BackgroundThe use of synthetic drugs has exceeded heroin to become a major public health concern in China. We aimed to estimate the trend of heroin-only, synthetic drug-only and poly-drug (heroin and synthetic drug) use during 2000–2030 period in China using existing data.MethodsWe used data from the Annual Report on Drug Control in China and peer-reviewed publications. We constructed a mathematical model to estimate the drug use trend based on Monte Carlo simulations.ResultsThe best calibrated model estimated that the number of drug users would increase from 0.86 million to 3,120,059 (95% CI 2,669,214-3,570,904) during 2000–2030 period. The proportion of heroin-only users among the total drug users will decrease from 96.8% (95% CI, 96.6–97.1%) in 2000 to 36.9% (30.1–40.8%) in 2030, while the proportion of synthetic drug-only users will increase from 1.1% (0.9–1.3%) in 2000 to 57.7% (51.7–65.6%) in 2030. In contrast, the proportion of poly-drug users shared an increasing trend during 2000–2016 (from 2.1% (1.5–2.8%) to 15.1 (13.8–17.1%)) but declined to 5.5% (3.4–7.2%) in 2030. Estimated 46,370 (41,634-51,106) heroin-only users and 3767 (3481–4053) synthetic drug only users initiated poly-drug use in 2000. We observed a cross-over in 2012 where more synthetic drug-only users were initiating heroin use than heroin-only users initiating synthetic drug use. There will be estimated 2,094,052 (1,819,830–2,368,274) synthetic drug-only users and poly-drug users 211,407 (177,150–245,664) in 2030.ConclusionsSynthetic drug use will become dominant in drug users in China, but poly-drug use of both heroin and synthetic drugs will remain substantial.     

捕获再捕获法估计四川乐山市中区吸毒人群基数

目的:使用捕获再捕获法估计乐山市中区现有吸毒人群基数。方法:利用强戒所建所以来资料确定平均捕获期和平均捕获间隔期及两次捕获起始点并收集相应时间段内的收戒人数。利用Lincoln-Petersen模型进行估计,定性和定量研究结合以解释说明估计结果等。结果:平均捕获期3.02月,平均捕获间期12.59月,两次捕获期起止时间点为2002年9月30日-2003年1月31日和2004年1月31日-2004年5月31日,对应收戒人数为234人和251人,重复捕获34人。不分层点估计数1742人,标准误240.45,95%CI1220-2163(人)。分层后合计点估计数为1645人,标准误225.46,95%CI1203-2087(人)。结论:75%位数捕获期和平均捕获间期为4个月和12个月,可满足分析需要。Lincoln-Petersen模型简单,费用低,可操作性强。估计结果存有一定程度的低估,可作为估计底限值。选择适当的捕获再捕获模型可提高估计精度。估计数为公安部门同期提供现有吸毒登记数的1.5倍。     

Factors associated with teenage ecstasy use

Aims: The aim of this article was to investigate the factors associated with ecstasy use in school-aged teenagers.

Methods: This was a longitudinal study of adolescent drug use, which was undertaken in three towns in Northern Ireland. A questionnaire was administered annually to participants. In this article ecstasy use patterns amongst a cohort of young people aged 14–16 years participating in the Belfast Youth Development Study (BYDS) was explored.

Findings: The percentage of those who had used ecstasy at least once increased from 7% when aged 14 years to 9% at 15 and 13% at 16 years. Female gender, delinquency, problem behaviours at school and the number of evenings spent out with friends each week were found to be significant variables predicting ‘ever use’ of ecstasy in all 3 years by logistic regression.

Conclusions: The findings suggest that ecstasy use patterns may be changing from their historical perception as a ‘party’ drug, as the demographic profile ecstasy of users in this study reflected the traditional profile of illicit drug use during adolescence, which raises challenges for addressing the problems associated with this drug.     

Towards an effective social care model for arrest referral: Implications for criminal justice interventions for problem drug users

Aims: To assess an operational model for arrest-referral schemes that successfully facilitates the entry of highly entrenched and chaotic problem drug users into specialist drug-treatment services. Methods: (1) An examination of case records from a voluntary arrest-referral service (SMART CJS) based across the Thames Valley region of the UK during 2002–2003; (2) Probablistic database linkage of agency case records with the National Drug Treatment Monitoring System (NDTMS); (3) participant observation and semi-structured interviews with agency staff.

Findings: Over half of problem drug users (58%) maintained contact with the scheme following initial contact in police custody. Referrals were made to a wide range of social-care services in addition to specialist drug treatment to include prison-based services, housing support and primary care. This model was able to demonstrate very high levels of specialist drug treatment uptake (53%) following referral. There was a close relationship between the average length of time a problem drug user entered treatment following contact in police custody and the average length of an active case file. Such an approach was considered essential to maintain motivation with clients.

Discussion: This social care model has operational validity in ensuring treatment uptake of recidivist problem drug-using offenders. Continuity of care alongside referrals addressing wider community harms including social exclusion and public health should be encouraged.     

Patterns of cocaine and opioid co-use and polyroutes of administration among street-based cocaine users in Montréal,Canada

BackgroundEffective public health programs aimed at problematic cocaine users are challenged by the fact that they can have complex patterns of drug use with respect to polysubstance use and routes of drug administration. This study was carried out to explore the presence of subgroups of cocaine users on the basis of their concurrent use of opioids and their routes of cocaine and opioid administration, and to determine if subgroups could be differentiated in terms of sociodemographic factors and risk behaviours.MethodsRegular cocaine users (≥1 per week) were recruited in low-threshold services located in the Montréal downtown area. The following variables were examined: demographic characteristics, types of drug used, routes of drug administration, and condom use with occasional or commercial sexual partners. Latent class analysis and multinomial logistic regression modeling were carried out.Results886 cocaine users were recruited (83.5% male: mean age 35.38 years). A 5-class model was identified: (1) “cocaine smokers” (CSs) (n = 161; membership probability (MP) = 0.183); (2) “cocaine smokers/sniffers” (CSSs) (n = 201; MP = 0.218); (3) “cocaine injectors” (CIs) (n = 207; MP = 0.231); (4) “cocaine-opioid injectors” (COIs) (n = 277; MP = 0.291); (5) “cocaine-opioid polyroute users” (COPs) (n = 40; MP = 0.077). Compared with COIs, other subtypes were significantly different in terms of either age, duration of cocaine use, ethnic background, homelessness, polydrug use or condom use.ConclusionThe heterogeneity of consumption patterns supports the importance of offering an array of interventions aimed at problematic cocaine users. These should include the provision of clean injecting and smoking material, the promotion of safe sexual behaviours and the prevention of initiation to drug injection. In the absence of specific treatment, cocaine users should have access to primary health care services and addiction treatment based on innovative behavioural and pharmacological approaches.     

Typology of cannabis use among adults: A latent class approach to risk and protective factors

BackgroundCannabis is among the most widely used substances worldwide. The United States has seen an increase in the number of adult daily cannabis users and in the number of adults diagnosed with cannabis use disorder. However, little work has examined patterns of use or unique subgroups of adult cannabis users, which may be useful in developing targeted treatment interventions for problematic cannabis users. Therefore, the current study used latent profile analysis to identify whether cannabis users can be categorized across distinct subgroups of adult users.MethodThe sample included 374 current cannabis using adults (64.2% Male; M_age = 32.6). Cannabis use frequency, quantity, and related problems were used to differentiate subgroups. Further, age, race, emotion dysregulation, affect, anxiety sensitivity, other substance use, and motives for cannabis use were examined as class correlates.ResultsResults supported five unique classes of cannabis users, generally ranging from light, infrequent users with few problems to heavy, frequent users with more problems. Additionally, race, negative affectivity, anxiety sensitivity, emotion regulation, cannabis use motives, and alcohol use emerged as unique predictors of class membership. The current findings substantiate past work for heterogeneous latent classes that underlie the larger cannabis using population, however, this study provides novel evidence for subgroups of adult users.ConclusionThe identification of different classes of cannabis users may inform future treatment interventions, and ultimately, lead to the development of personalized treatments for each class based on correlates of group membership.     

Mortality of registered drug users in Central Asia

BackgroundWithin the fifth phase of the Central Asia Drug Action Programme (CADAP) covering five post-Soviet Central Asian countries, an analysis of the mortality of drug users was performed. The results for Kazakhstan and Uzbekistan are presented in detail in this paper since results from Kyrgyzstan and Tajikistan are not considered valid and Turkmenistan did not provide data at all.MethodsA system of registration of all users of illegal drugs known to the health and/or law enforcement authorities (“narcological registers”) exists in Central Asian countries inherited from the system of Soviet “narcology”. According to the legal norms, the death of a registered person should be recorded. We conducted indirect standardisation of crude mortality rates and computed the standardised mortality ratio (SMR) comparing observed number of deaths with expected number of deaths according to age and gender specific mortality rates in the general population of the same country.ResultsThe results show excess mortality in registered drug users, particularly in registered females, in Uzbekistan (the latest available SMR for all those registered is 7.4; the SMR in females is 16.3) and Kazakhstan (4.0 and 12.9). The excess mortality is highest among young adults (18–34) in all the studies.ConclusionTaking into account the limited quality and reliability of the data – first of all, the likely under-reporting of deaths in the narcological registers – the crude mortality rate among registered drug users is quite high when compared to EU countries. The SMR in total is comparably lower as a result of the high background mortality in the general population. This excess mortality is preventable and should be targeted by the national drug policies. Specifically, the programmes should target registered and unregistered female drug users.     

Evaluation of dystonia in children and adolescents treated with atomoxetine within the Truven MarketScan database: a retrospective cohort study

Objective: Atomoxetine is a non-stimulant drug indicated for the treatment of attention-deficit/hyperactivity disorder in children aged ≥6 years, adolescents, and adults. In this retrospective cohort study, the incidence and risk of dystonia in children and adolescents treated with atomoxetine was compared to a propensity score-matched cohort of stimulant users.

Methods: Data between 1 January 2006 and 31 December 2014 from patients aged 6–17 years in the Truven Health Analytics MarketScan database were used to generate two cohorts of patients: (1) atomoxetine users and (2) stimulant (methylphenidates or amphetamines) users. A Cox proportional hazards regression model was used to compare incidence of dystonia across propensity score-matched cohorts.

Results: Of the 70,657 atomoxetine users, 70,655 users were propensity score-matched to a stimulant user. In the atomoxetine- and stimulant-treated cohorts, the crude incidence rates of dystonia were 54.9 (95% CI: 27.1–82.7) and 77.9 (95% CI: 49.1–106.8) per 100,000 person-years, respectively. The hazard ratio for occurrence of dystonia with atomoxetine use relative to stimulant use was 0.68 (95% CI: 0.36 ? 1.28; P = 0.23).

Conclusion: In this large retrospective cohort study, there was no significant difference in incidence or risk of dystonia among patients treated with atomoxetine compared to stimulants.     

Examining differential effects of psychosocial treatments for cocaine dependence: An application of latent trajectory analyses

BackgroundThe NIDA Collaborative Cocaine Treatment Study yielded different efficacies for different psychosocial treatments for cocaine dependence. However, substantial heterogeneity of patient outcomes was evident. Longitudinal data analysis techniques can be helpful in examining differential effects of psychosocial interventions on specific subpopulations of patients.MethodsOverall drug and cocaine use of 346 patients diagnosed with DSM-IV cocaine dependence and treated with one of four psychosocial interventions were assessed monthly during 6-month treatment. Growth mixture models were used to identify patient subgroups based on typical patterns of change in substance use during treatment and to evaluate differential treatment effects within these subgroups.ResultsThree patient subgroups following different change patterns in cocaine and overall drug use were identified irrespective of the treatment type: (a) those with moderate baseline severity of drug use and very rapid reduction of drug use during treatment, (b) those with moderate baseline severity of drug use and moderate reduction of drug use during treatment, and (c) those with severe levels of baseline drug use with moderate reduction of drug use during treatment. Patient baseline characteristics enabled discrimination between these subgroups. Individual drug counseling was most efficacious among those patients with moderate baseline severity and moderate treatment response. There were no differential treatment effects in the two other patient subgroups.ConclusionsThe population of treatment-seeking cocaine dependent individuals is heterogeneous. Research on patient subgroups with different change patterns revealed its potential to enable classifications of patients that indicate which treatment is most effective for which type of patient.     

Declining trends in drug dealing among adolescents in the United States

IntroductionThe link between drug selling and other delinquent behaviors in adolescence is well established. Less is known regarding the trends in drug selling among youth in the US and whether they are consistent with the recently observed decline in problem behaviors among this population.MethodsData were collected between 2002 and 2015 as part of the National Survey on Drug Use and Health (NSDUH). Participants included 233,435 US youth aged 12–17. The primary variable of interest was self-reported past year drug-selling. Logistic regression assessed trends in drug-selling among male and female subgroups.ResultsBetween 2002 and 2015, the prevalence of drug-selling decreased significantly across all youth (AOR = 0.970, p < .001). Analysis of gender differences revealed that the rate of drug-selling decreased significantly among boys (AOR = 0.962, p < .001), however, the trend remained stable for girls (AOR = 0.987, p > .05). The decrease in drug-selling was observed for nearly all male subgroups, African-American girls (0.946, p < .01) and girls reporting no illegal substance use in the past year (0.960, p < .05).ConclusionsThe prevalence of past year drug-selling among youth in the US is declining significantly, especially for boys.     

Factors Contributing to Retention of Not-in-Treatment Drug Users in an HIV/AIDS Outreach Prevention Project

SUMMARY

Studies have attempted to identify the characteristics of substance-abusing clients that are related to premature termination from alcohol and drug treatment. Few studies, however, have looked at predictors of loss to follow-up among drug users participating in HIV/AIDS prevention projects. This paper develops and tests models of program retention employing data from approximately 250 not-in-treatment drug users enrolled in an outreach based HIV risk reduction program. Logistic regression was used to fit a model which included measures of: (1) demographic characteristics including: age and ethnicity; (2) social environmental factors including: living situation and type of network connection; (3) risk behaviors including: composite scores for drug use in the past 30 days and history of Sexually Transmitted Diseases (STDs); and (4) program factors including: outreach workers' knowledge of clients and number of intervention sessions received. Findings suggest that social environmental and program factors are most predictive of client retention in the program. Implications for ways in which to monitor retention of out-of-treatment drug users participating in AIDS prevention programs are addressed.     

Gender and regional differences in client characteristics among substance abuse treatment clients in the Europe

Aims: To assesses the extent of the gender gap among the treated population of drug users across Europe.

Methods: This analysis reports data on 363,170 clients from 4647 treatment units in 23 countries (22 European Union member states and Switzerland).

Findings: Overall, males outnumber females by four, but the gender ratio varies not only by geographical region/country, but also by drug. In the majority of countries, the most common primary problem drug is opioids, and the overall gender ratio mirrors the gender ratio of opioid users. In some countries, a considerable proportion of treated drug users have cannabis and stimulants (cocaine/amphetamines/methamphetamines) as primary problem drugs. Stimulants other than cocaine and other drugs have lower, while cannabis has a higher than overall male-to-female gender ratio.

Conclusions: The very high male-to-female gender ratios may reveal differential access to treatment. Our findings highlight the need to assess access to treatment for women problem drug users and to make women-focussed programmes more available to increase the proportion of women in drug treatment programmes across Europe.     

Minimal uptake of sterile drug preparation equipment in a predominantly cocaine injecting population: implications for HIV and hepatitis C prevention

ObjectiveTo identify factors associated with using sterile drug injection equipment by injection drug users (IDUs).Methods275 IDUs were recruited from syringe exchange programs in Montreal, Canada in 2004–2005. A structured, interviewer-administered questionnaire collected information about demographics, drug injection practices, self-reported HIV and hepatitis C virus (HCV) status, and harm reduction behaviours. Logistic regression was used to model variables in relation to the use of sterile syringes, containers, filters, and drug preparation water.ResultsSterile syringes, containers, filters, and water were used for at least half of injecting episodes by 95%, 23%, 23%, and 75% of subjects, respectively. In multivariate analysis, users of sterile syringes had higher odds of being older and injecting alone, and were less likely to report problems obtaining sterile syringes and requiring or providing help with injecting. Using sterile filters was associated with having at least high school education, injecting heroin, and injecting alone. In addition to the factors associated with filters, users of sterile containers were more likely to be HCV-negative and older. Using sterile water was associated with daily injecting and being HCV-negative.ConclusionsImproving the uptake of sterile drug preparation equipment among IDUs could be aided by considering drug-specific risks, such as drug of choice and injecting context, while reinforcing existing messages on safer injecting. The association between sterile equipment use and HCV-negative status may be representative of an established subgroup of safer injectors who have remained free of infection because of consistent safe injecting practices.