Hidden need for drug treatment services: measuring levels of problematic drug use in the North West of England

Self reported health status, and health service contact, of illicit drug users aged 50 and over: a qualitative interview study in Merseyside, United Kingdom

Background

The populations of industrialised countries are ageing; as this occurs, those who continue to use alcohol and illicit drugs age also. While alcohol use among older people is well documented, use of illicit drugs continues to be perceived as behaviour of young people and is a neglected area of research. This is the first published qualitative research on the experiences of older drug users in the United Kingdom.

Methods

Semi-structured interviews were conducted in Merseyside, in 2008, with drug users aged 50 and over recruited through drug treatment services. Interviews were recorded and transcribed and analysed thematically. Only health status and health service contact are reported here.

Results

Nine men and one woman were interviewed (age range: 54 to 61 years); all but one had been using drugs continuously or intermittently for at least 30 years. Interviewees exhibited high levels of physical and mental morbidity; hepatitis C was particularly prevalent. Injecting-related damage to arm veins resulted in interviewees switching to riskier injecting practices. Poor mental health was evident and interviewees described their lives as depressing. The death of drug-using friends was a common theme and social isolation was apparent. Interviewees also described a deterioration of memory. Generic healthcare was not always perceived as optimal, while issues relating to drug specific services were similar to those arising among younger cohorts of drug users, for example, complaints about inadequate doses of prescribed medication.

Conclusion

The concurrent effects of drug use and ageing are not well understood but are thought to exacerbate, or accelerate the onset of, medical conditions which are more prevalent in older age. Here, interviewees had poor physical and mental health but low expectations of health services. Older drug users who are not in contact with services are likely to have greater unmet needs. The number of drug users aged 50 and over is increasing in Europe and America; this group represent a vulnerable, and in Europe, a largely hidden population. Further work to evaluate the impact of this change in demography is urgently needed.

Estimating the prevalence of ex-injecting drug use in the population

Injecting drug use is the main route of transmission for the hepatitis C virus in the developed world. Knowledge about the characteristics of the past and current injecting drug user (IDU) population is therefore vital in order to understand the epidemiology of hepatitis C. The IDU population is ;hard to reach' and hence most epidemiological studies have concentrated on estimating current IDU prevalence, whilst little is known about the potentially large pool of ex-injectors. We demonstrate a method for estimating the proportion of ex-users in the population, by considering injecting drug use as a time-to-event process. We show how unbiased estimates of injecting duration and historical patterns in injecting initiation can be derived from a sample of ex-IDUs obtained from a population survey, and how such data lead to estimates of the proportion of ex-IDUs in the population. Finally, we show how to obtain estimates of the prevalence of ex-IDUs by using additional information on the prevalence of current IDUs.

Capture—recapture and anchored prevalence estimation of injecting drug users in England: national and regional estimates

Capture—recapture (C—RC) using four data sources, one of which accounted for 81% of captured injectors, and multiple indicator methods (MIM) were used to obtain national, regional and local estimates of the prevalence of injecting drug use among opiate and/or crack cocaine users in England. Persons aged 15 to 64 years, in contact with health and/or criminal justice services during 2005/2006, and known to be using opiates and/or crack cocaine and injecting drugs were included in the C—RC analysis. The MIM analysis included indicators relating to drug treatment, drug-related deaths, population density and drug offences.

There were an estimated 130,000 opiate and/or crack cocaine users who injected drugs in 2005/06 (95% confidence interval 125,800 to 137,000), corresponding to 3.9 per thousand of the population aged 15 to 64 years (95% confidence interval 3.8—4.1). Regional variation in the prevalence of injecting was evident, ranging from 6.1 per thousand of the population aged 15 to 64 years in Yorkshire and the Humber (95% confidence interval 5.6 to 6.6) to 2.3 per thousand in the East of England (95% confidence interval 1.8 to 2.9). Application of gender and age-group distributions for treated injecting drug users (IDUs) to the prevalence estimates suggested that there were 97,200 male injectors (95% confidence interval 94,000 to 102,500) and 63,600 female injectors aged 25 to 34 years (95% confidence interval 61,500 to 67,000).

The prevalence estimates provide a basis from which numbers of current IDUs infected with hepatitis C virus (HCV) can be approximated.

Estimating current injectors in Scotland and their drug-related death rate by sex, region and age-group via Bayesian capture--recapture methods

Using Bayesian capture-recapture methods, we estimate current injectors in Scotland in 2003, and, thereby, injectors' drug-related death rates for the period 2003-2005. Four different data sources are considered [Hepatitis C Virus (HCV) database, hospital admissions, social enquiry reports, and drug misuse database reports by General Practices or Drug Treatment Agencies] which provide covariate information on sex, region (Greater Glasgow versus elsewhere in Scotland) and age group (15-34 years and 35+ years).We quantified Scotland's current injectors in 2003 at 27,400 (95% highest probability density interval: 20,700-32,100) by incorporating underlying model uncertainty in terms of the possible interactions present between data sources and/or covariates. The posterior probability was 72% that Scotland had more current injectors in 2003 than in 2000. Detailed comparison with 2000 gave evidence of importantly changed numbers of current injectors for different covariate classes.In addition, and of particular social interest, is the estimation of injectors' drug-related death rates. Expert information was used to construct upper and lower bounds on the number of drug-related deaths pertaining to injectors, which were then used to provide bounds on injectors' drug-related death rates. Failure to incorporate expert information could result in over-estimation of drug-related death rates for subclasses of injectors.

Factors predicting drop out from, and retention in, specialist drug treatment services: a case control study in the North West of England

BACKGROUND

In the United Kingdom (UK), the National Treatment Agency for Substance Misuse (NTA) considers retention to be the best available measure of drug treatment effectiveness. Accordingly, the NTA has set local treatment systems the annual target of retaining 75% of clients for 12 weeks or more, yet little assessment of this target or factors that improve retention has occurred. This study aims to quantify the proportion of people retained in treatment for 12 weeks in the North West of England and to identify factors associated with premature drop out.

METHODS

The North West National Drug Treatment Monitoring System (NDTMS) was used to identify treatment durations for everyone beginning a treatment episode between 1st April 2005 and 31st March 2006 (N = 16626). Odds ratios, chi-square and logistic regression analyses compared clients retained for 12 weeks to clients whose discharge record showed they had prematurely dropped out before 12 weeks. Individuals with other outcomes were excluded from analyses.

RESULTS

75% of clients (N = 12230) were retained for 12 weeks and 10% (N = 1649) dropped out prematurely. Multivariate analysis showed drop out was more likely among Asian drug users (adjusted odds ratio 1.52, 95% CI 1.12 to 2.08) than their white equivalents. Drop out was more likely among residents of Cumbria and Lancashire (adjusted odds ratio 1.80, 95% CI 1.51 to 2.15) and Greater Manchester (adjusted odds ratio 2.00, 95% CI 1.74 to 2.29) than Cheshire and Merseyside and less likely among alcohol users (adjusted odds ratio 0.73, 95% CI 0.59 to 0.91). A significant interaction between age and deprivation was observed. For those aged 18 to 24 years and 25 to 34 years, drop out was significantly more likely among those living in affluent areas. For those in the older age groups the converse effect was observed.

CONCLUSION

In combination, the drug treatment systems of the North West achieved the Government's retention target in 2005/06. A number of factors associated with drop out were identified; these should be considered in strategies that aim to improve retention. Drop out and retention are measures that capture the joint effect of many factors. Further work is required to evaluate the effect of deprivation.

Problematic drug use, ageing and older people: trends in the age of drug users in northwest England

In the United Kingdom (UK) and elsewhere, little is known about problematic drug use among older people (defined here as aged 50–74 years), either because few older drug users exist or because they represent a ‘hidden’ population. In this paper, we show that the average age of drug users in contact with treatment services and agency-based syringe exchange programmes (SEPs) in the counties of Cheshire and Merseyside in northwest England is rising. Between 1998 and 2004–05, the number of older male drug users in treatment increased from 80 to 310, and the number of older females rose from 46 to 117. Consequently, the median age rose from 30.8 years in 1998 to 34.9 years in 2004–05. Similarly, between 1992 and 2004, the number of older injectors accessing SEPs increased from three to 65 men and from one to nine women. The median age of SEP attenders was 27.0 years in 1992 and 34.9 years in 2004. Drug use amongst older people is associated with poor physical and psychological health and longer hospital stays. The future cost of the ageing of drug users may be considerable. Detailed research is needed to identify the characteristics and health needs of this vulnerable population.

Trends in drop out, drug free discharge and rates of re-presentation: a retrospective cohort study of drug treatment clients in the North West of England

Background

Governments aim to increase treatment participation by problematic drug users. In the UK this has been achieved by fiscal investment, an expanded workforce, reduced waiting times and coercive measures (usually criminal justice (CJ) led). No assessment of these measures on treatment outcomes has been made. Using established monitoring systems we assessed trends in 'dropped out' and 'discharged drug free' (DDF), since the launch of the national drug strategy, and rates of treatment re-presentation for these cohorts.

Methods

A longitudinal dataset of drug users (1997 to 2004/05, n = 26,415) was used to identify people who dropped out of, and were DDF from, services for years 1998 to 2001/02, and re-presentations of these people in years to 2004/05. Trends in drop out and DDF, baseline comparisons of those DDF and those who dropped out and outcome comparisons for those referred from the CJ system versus other routes of referral were examined using chi square. Logistic regression analyses identified variables predicting drop out versus DDF and subsequent re-presentation versus no re-presentation.

Results

The proportion of individuals dropping out has increased from 7.2% in 1998 to 9.6% in 2001/02 (P < 0.001). The proportion DDF has fallen from 5.8% to 3.5% (P < 0.001). Drop out was more likely in later years, by those of younger age and by CJ referrals. The proportion re-presenting to treatment in the following year increased from 27.8% in 1998 to 44.5% in 2001/02 (P < 0.001) for those DDF, and from 22.9% to 48.6% (P < 0.001) for those who dropped out. Older age and prior treatment experience predicted re-presentation. Outcome (drop out or DDF) did not predict re-presentation.

Conclusion

Increasing numbers in treatment is associated with an increased proportion dropping out and an ever-smaller proportion DDF. Rates of drop out are significantly higher for those coerced into treatment via the CJ system. Rates of re-presentation are similar for those dropping out and those DDF. Encouragingly, those who need to re-engage with treatment, particularly those who drop out, are doing so more quickly. The impact of coercion on treatment outcomes and the appropriateness of aftercare provision require further consideration.

The prevalence of problem drug misuse in a rural county of England

Previous capture-recapture studies have estimated the prevalence of problem drug misuse in urban areas. This study estimates the prevalence in a rural county, Norfolk, using data from four sources: drug treatment agencies, probation, the arrest referral service, and police (drug-related crime with/without acquisitive crime). Careful consideration was given to methods of matching datasets and sensitivity analyses involved altering matching rules and postcode criteria. Whilst it is recognised that acquisitive crime is often related to drug use, this is the first capture-recapture study to incorporate acquisitive crime data. In further sensitivity analyses the proportion of acquisitive crime assumed to be drug-related was varied from 25-60%. The main analysis provided an estimated prevalence of problem drug use in Norfolk of 2.05% (95% confidence interval: 1.66%-2.56%) for ages 15-54 years, considerably higher than the 1.1% currently suggested for the UK. Sensitivity analyses based on varied matching and postcode criteria produced estimates ranging from 2.41%-3.37%, suggesting our estimate may be conservative. Sensitivity analyses assuming that 25-60% of acquisitive crimes were drug-related, produced estimates ranging from 2.02% to 5.73%, further supporting our main analysis. In conclusion, this study provides evidence that problem drug misuse is more prevalent in this rural population than previously thought.

Prior information in behavioral capture-recapture methods: demographic influences on drug injectors' propensity to be listed in data sources and their drug-related mortality

The authors present findings from a Bayesian analysis of Scotland's four primary capture-recapture data sources for 2000 that was carried out to estimate numbers of current injecting drug users by region (Greater Glasgow vs. elsewhere in Scotland), sex (male vs. female), and age group (15-34 years vs. > or =35 years). A secondary goal of the analysis was to obtain Bayesian estimates and credible intervals for the demographic influences on Scotland's drug-related death rate per 100 current injectors. Incorporation of informative priors altered the models with highest posterior probability. Expert opinion on how demography influenced Scottish drug injectors' propensity to be listed in different data sources was taken into account, along with external information about European injectors' drug-related death rates and male:female ratios. Higher drug-related mortality was confirmed in older drug injectors and those outside of Greater Glasgow. Female injectors' lower drug-related death rate was not sustained beyond 34 years of age. The authors recommend that demographic influences be accommodated in behavioral capture-recapture estimation, especially when it is a prelude to secondary analysis, such as the analysis of drug-related death rates presented here.

Capture-recapture estimates of problem drug use and the use of simulation based confidence intervals in a stratified analysis

STUDY OBJECTIVE

To establish the prevalence of problem drug use in the 10 local authorities within the Metropolitan County of Greater Manchester between April 2000 and March 2001.

SETTING AND PARTICIPANTS

Problem drug users aged 16-54 resident within Greater Manchester who attended community based statutory drug treatment agencies, were in contact with general practitioners, were assessed by arrest referral workers, were in contact with the probation service, or arrested under the Misuse of Drugs Act for offences involving possession of opioids, cocaine, or benzodiazepines.

DESIGN

Multi-sample stratified capture-recapture analysis. Patterns of overlaps between data sources were modelled in a log-linear regression to estimate the hidden number of drug users within each of 60 area, age group, and gender strata. Simulation methods were used to generate 95% confidence intervals for the sums of the stratified estimates.

MAIN RESULTS

The total number of problem drug users in Greater Manchester was estimated to be 19 255 giving a prevalence of problem drug use of 13.7 (95% CI 13.4 to 15.7) per 1000 population aged 16-54. The ratio of men to women was 3.5:1. The distribution of problem drug users varied across three age groups (16-24, 25-34, and 35-54) and varied between the 10 areas.

CONCLUSIONS

Areas in close geographical proximity display different patterns of drug use in terms of prevalence rates and age and gender patterns. This has important implications, both for future planning of service provision and for the way in which the impact of drug misuse interventions are evaluated.

Injecting drug use in Brighton, Liverpool, and London: best estimates of prevalence and coverage of public health indicators

STUDY OBJECTIVE

To estimate the prevalence of injecting drug use (IDU) in three cities in England and to measure the coverage of key public health indicators.

DESIGN

Capture-recapture techniques with covariate effects.

SETTING

Liverpool, Brighton, and 12 London boroughs, 2000/01.

PARTICIPANTS

IDU collated and matched across five data sources-community recruited survey, specialist drug treatment, arrest referral, syringe exchange, and accident and emergency-896 in Brighton, 1224 in Liverpool, and 6111 in London.

MAIN RESULTS

It is estimated that in 2000/01 the number and prevalence of IDU aged 15-44 was 2300 (95%CI 1500 to 3700) and 2.0% (95%CI% 1.3% to 3.2%) in Brighton; 2900 (95%CI 2500 to 5000) and 1.5% (95%CI 1.3% to 2.6%) in Liverpool; 16 700 (95%CI 13 800 to 21 600) and 1.2% (95%CI 1.0% to 1.6%) in 12 London boroughs; with a prevalence of 1.7% (95%CI 1.2% to 3.3%) in inner London. It is estimated that: less than one in four IDU are in treatment in the three areas; syringe exchange programmes covered about 25% of injections in Brighton and Liverpool and 20% in London; and that the annual opioid mortality rate among IDU was 2% in Brighton compared with less than 1% in Liverpool and London.

CONCLUSIONS

Credible estimates of the prevalence of injecting drug use (and key public health indicators) can be determined using covariate capture-recapture techniques. These suggest that: targets to double the number in treatment are possible: syringe distribution should be increased; and further attention, especially in Brighton, given to reducing overdose mortality.