- Email: [email protected]
‘Topping up’ methadone: An analysis of patterns of heroin use among a treatment sample of Scottish drug users
Public Health (2008) 122, 1013e1019
www.elsevierhealth.com/journals/pubh
Original Research
‘Topping up’ methadone: An analysis of patterns of heroin use among a treatment sample of Scottish drug users M. Bloora,*, J. McIntosha, N. McKeganeya, M. Robertsonb a
Centre for Drug Misuse Research, University of Glasgow, 89 Dumbarton Road, Glasgow G11 6PW, UK Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK
b
Received 14 February 2007; received in revised form 29 November 2007; accepted 30 January 2008 Available online 19 May 2008
KEYWORDS Methadone maintenance; Drug use; Cohort study
Summary Objectives: To determine: (a) whether Scottish drug users on methadone maintenance use heroin less frequently than their peers following other forms of drug treatment; and (b) to what extent those on methadone maintenance ‘top up’ with heroin. Design: A cohort study followed-up for 33 months from 2001 to 2004. Methods: Four hundred and ten interviewees who responded at all four interview sweeps, recruited as new treatment entrants from 28 drug treatment agencies across Scotland. Results: Sixty-eight of the 401 interviewees had commenced an episode of methadone-maintenance treatment at the start of the study. There was no significant difference between the methadone-maintained sample and the other interviewees in their propensity to abstain from heroin use, nor was there any difference between the two groups in the mean reduction over time in their self-reported dependence on drugs. However, if the outcome measure used is the change (between baseline and 33 months) in the number of days that the interviewee reported having used heroin in the previous 3 months, the reduction in the number of days that heroin was used was significantly greater (52 days) in the methadone-maintained group than in the rest of the sample (36.4 days). This fall in the number of days of heroin use was greater still if the comparison was restricted to those who had continued on methadone-maintenance treatment, although 67.4% of those still on methadone maintenance had ‘topped up’ with heroin at some point in the 3 months prior to 33-month follow-up. Those on higher maintenance doses were not significantly more likely to have reduced the number of days on which they used heroin compared with those on lower doses, and those still on methadone maintenance were not more likely to have reduced their criminality (measured by the number of days on which they committed acquisitive crimes in the previous 3 months) compared with the rest of the sample.
* Corresponding author. Tel.: þ44 (0) 141 330 2670; fax: þ44 (0) 141 330 2820. E-mail address: [email protected] (M. Bloor). 0033-3506/$ - see front matter ª 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.puhe.2008.01.007
1014
M. Bloor et al. Conclusions: Methadone-maintained drug users are not more likely to achieve abstinence than drug users receiving other forms of treatment, but they are significantly more likely to achieve a reduction in the frequency of their illicit drug use; they ‘top up’ on methadone, but the frequency of their illicit drug use is less than that of drug users in other treatment modalities. These data confirm the value of methadone-maintenance services as part of a ‘mixed economy’ of services for the treatment of drug use. ª 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.
Introduction ‘They [the doctors] always think that if you don’t stick to your methadone and you’re still using smack [heroin] on top of it, then it’s not working. That’s not the case at all and I know that’s true for an awful lot of people. That is a very important point e methadone still works even if you’re abusing on top of it, because you can use it to stop yourself from getting in jail, to stop yourself from going out on the game, and to keep your children with you.’ The above quotation,1 from a drug user on methadone maintenance who still ‘topped up’ by intermittent heroin use, neatly encapsulates the counter-argument to those who would claim that substitute prescribing is ‘not working’ if drug users in treatment continue to use heroin. If heroin users are only ‘topping up’, the counter-argument goes, then their overall consumption of heroin is much reduced, their health risks are reduced and their criminality is reduced. This is an aspect of the broader ‘harm-reduction’ approach in drugs policy2 which promotes interventions to contain and ameliorate drug-related harms to individuals and the wider community, alongside the pragmatic recognition that interventions to eliminate drug use are unlikely to be wholly successful. Methadone maintenance is a central component of harm-reduction policies in the UK.3,4 It involves the administration (usually by a non-parenteral route and usually daily) of the long-acting (24e 36 h) opioid to an opioid-dependent person on a maintenance basis, in order to improve the health status and psychological and social well-being of the opiate-dependent person. Once improvement has occurred, patient and doctor may concur in moving to a progressively reducing dosage.5 Between 1995 and 2005, the number of substitute opiate prescriptions in England is estimated to have doubled, with 83% of them for methadone.6 The extensive research literature concentrates on
issues of treatment effectiveness in trials,7 reviews8 and meta-analyses,9 or on issues of treatment delivery.10 Although ‘topping up’ seems to be a frequent practice, its extensiveness has seldom been described. Raffa et al. reported that only four out of 60 patients in a Canadian methadone maintenance and HIV medication programme abstained from all illicit drug use.11 The present study aimed to estimate the extent, if any, to which drug users who ‘topped up’ were are using less illicit drugs than their peers who were not receiving substitute methadone prescribing.
Methods The Drug Outcome Research in Scotland (DORIS) study is a cohort study of 1007 drug users recruited in 33 drug treatment agencies (both community-based and prison-based) across Scotland in 2001/2002. The baseline treatment offered at sample recruitment was methadone (27%), other prescribed drugs (dihydrocodeine, diazepam, temazepam, lofexidine, MXL) (29%), residential detoxification (12%), residential rehabilitation (12%), counselling (14%) and group work (4%). Methadone treatment may be short term on a reducing dose, or longer term on a maintenance dose. In this study, baseline treatment was self-reported by the interviewee, rather than being defined by the service provider or the researcher. The mean methadone dose for those on methadone maintenance was 55.4 mg (median dose 50 mg, range 12e120 mg). This may be considered quite a low mean dose, as the UK guidelines for a maintenance dose are 60e120 mg3; however, it is comparable with the mean dose of 56.3 mg found in a large survey of pharmacies in England in 2005.6 Since very few prisoners in Scotland had access to methadone-maintenance treatment in 2001, the prison-recruited respondents have been excluded from these analyses. DORIS respondents were followed-up at 8 months (DORIS2), 16 months (DORIS3) and 33 months (DORIS4), with response
Patterns of heroin use among Scottish drug users rates of eligible respondents of 85%, 79% and 70%, respectively. The DORIS4 analyses were therefore conducted on those respondents recruited in community-based agencies and interviewed at all four sweeps (n ¼ 410, see Fig. 1). The sociodemographic profile of the DORIS respondents is comparable with the profile of returns made to the Scottish Drug Misuse Database of all drug users entering treatment in 2001.12 Sixty-nine percent of DORIS respondents were male and their mean age was 28 years. The 28 agencies, other than prisons, from which DORIS respondents were recruited included 19 community drug agencies, five residential drug treatment agencies (both detoxification and rehabilitation agencies), three general practices and one pharmacy. The first 275 DORIS respondents were asked to provide oral fluid samples for drug testing. Concordance with reporting was 94% for methadone, 86% for opiates, 81% for benzodiazepines and 80% for cannabis, with testing failing to identify reported drug use more often than unreported drug use.13 The great majority of respondents were polydrug users, but 81% reported that their main drug was heroin, with 5% citing diazepam, 5% citing methadone, 3% citing cannabis and less than 2% citing either cocaine, crack, dihydrocodeine, amphetamine, buprenorphine or ecstasy as their main drug. Logistic regression analysis of attrition bias at DORIS4 showed that differential attrition had only occurred in respect of two variables; being a prisoner and being homeless at DORIS1. DORIS1 (1007 respondents)
Deaths and lost to follow-up (n=354)
DORIS respondents to all four sweeps (n=653)
Prison-based treatment (n=252) Treatment outside prison (n=410)
Other non-prison treatments (n=342) Methadone-maintenance treatment (n=68)
Figure 1
The DORIS sample.
1015 Interviews were unnamed and voluntary and took between 1 and 2 h. Ethical oversight was exercised by the Scottish Multicentre Research Ethics Committee. The standard instruments used had been developed and validated in other studies; the measure of self-reported drug dependence was developed specifically for use with drug treatment populations, including methadone-maintained patients.14 More detailed reports of the study methods have been published elsewhere,12 as have reports of other DORIS study outcomes such as changes in health status.15
Results Sixty-eight of the 401 DORIS interviewees at 33month follow-up were receiving methadone maintenance as baseline treatment. If one takes as a measure of performance, whether or not the interviewee had ever used heroin in the 3 months prior to interview, 21 (30.9%) of those on methadone maintenance had improved over the 33 months, compared with 140 (40.9%) of those on other treatments; this difference was not significant (Chi-squared test: P ¼ 0.1210). Likewise, if one takes change in severity of dependence scores as a measure of performance, the fall in mean score over the 33 months in the interviewees receiving methadone maintenance was not significantly different from the fall in mean score among those receiving other forms of treatment (Table 1). However, Table 1 also shows performance as measured by change in the number of days in which they had used heroin in the last 3 months. Between baseline and 33 month followup, the average fall in the number of days that interviewees used heroin was 52 for those on methadone maintenance at baseline, compared with 36.4 days for those receiving other treatments. Many of those who had received methadone maintenance were ‘topping up’ with heroin, but they were using heroin on significantly fewer days than those who had undergone different treatments. This relative advantage that methadone maintenance has over other treatments, in changed frequency of heroin use, is more apparent still if one compares, not those who started on methadone maintenance (68 interviewees) with the rest of the sample, but rather those who remained in methadone-maintenance treatment (46 interviewees) with the rest of the sample. No significant difference was found between the two treatment groups in changes in those who had ever used heroin in the last 3 months; 15 (32.6%) of those on methadone maintenance had improved compared
1016
M. Bloor et al.
Table 1 Changes in frequency of heroin use and in dependence score among those receiving methadone maintenance at baseline.
Change in SD (dependence) score (DORIS1eDORIS4) Change in days when used heroin in the last 3 months (DORIS1eDORIS4)
Baseline treatment: methadone maintenance (n ¼ 68)
All other (non-prison) treatments (n ¼ 342)
P-value (two-sample t-test)
Mean (SD)
Mean (SD)
5.1 (4.6)
4.8 (5.6)
0.6988
52.0 (41.7)
36.4 (41.5)
0.0050
SD, standard deviation.
with 146 (40.1%) among the rest (Chi-squared test: P ¼ 0.3263). Table 2 shows no significant difference in changes in dependence scores between the two groups (P ¼ 0.7523). However, the mean fall in the number of days using heroin was 57.2 among those starting methadone maintenance at baseline who were still in contact with the treatment agency, compared with 36.7 days for the rest of the sample (P ¼ 0.0017). For those still on methadone maintenance 33 months later, the mean number of days on which they had used heroin in the last 3 months was 17.6 days, compared with 22.6 days for the rest of the sample; the median number of days was 3. Other studies have found that higher doses are more treatment effective,16 so it was relevant to establish whether or not those interviewees on relatively high doses showed the greatest reductions in frequency of use. Due to small subsample sizes, this comparison is only shown for changes in dependence score and frequency of heroin use between DORIS1 and DORIS2 (an 8-month period, rather than a 33-month period). Again, no significant difference was observed between those on higher and lower maintenance doses in changes in whether they had ever used heroin in the last
3 months; 12 (54.5%) of the 22 interviewees on higher doses had improved, compared with 51 (66.2%) interviewees on lower doses (Chi-squared test: P ¼ 0.3149). Table 4 compares the performances of those receiving high doses of methadone (more than one standard deviation above the mean, i.e. 79.4 mg) with those receiving lower doses, in respect of changes in dependence scores and changes in frequency of heroin use. As in Tables 1 and 2, no significant differences were found in respect of changes in dependence scores in Table 3 (P ¼ 0.5854). Those on higher doses did report a slightly larger fall in the frequency of heroin use (57.8 days vs 48.0 days), but this was not significant (P ¼ 0.2781). Table 4 shows changes between baseline and DORIS4 in self-reported criminality, in terms of changes in the number of days on which interviewees reported that they committed acquisitive crimes (defined as drug dealing, house breaking, shop lifting and thefts from persons) and changes in the number of days on which interviewees reported that they had been arrested for acquisitive crimes. The comparison made is between those methadone-maintenance interviewees still in contact with their treatment agency and the rest of
Table 2 Changes in frequency of heroin use and in dependence score among those receiving methadone maintenance at baseline and still in contact with the treatment agency.
Change in SD (dependence) score (DORIS1eDORIS4) Change in days when used heroin in the last 3 months (DORIS1eDORIS4) SD, standard deviation.
P-value (two-sample t-test)
Baseline treatment: methadone maintenance and still in contact with agency (n ¼ 46)
All other (non-prison) treatments (n ¼ 364)
Mean (SD)
Mean (SD)
5.1 (4.6)
4.8 (5.5)
0.7523
57.2 (35.9)
36.7 (42.0)
0.0017
Patterns of heroin use among Scottish drug users
1017
Table 3 Changes in frequency of heroin use and in dependence score among those receiving high methadonemaintenance doses versus others on maintenance doses.
Change in SDS (dependence) score (DORIS1eDORIS2) Change in days when used heroin in the last 3 months (DORIS1eDORIS2)
P-value (two-sample t-test)
Baseline treatment: methadone maintenance and methadone dose more than 1 SD above the mean (n ¼ 22)
Baseline treatment: methadone maintenance and methadone dose less than 1 SD above the mean (n ¼ 77)
Mean (SD)
Mean (SD)
5.9 (4.0)
5.3 (4.8)
0.5854
57.8 (37.9)
48.0 (36.8)
0.2781
SD, standard deviation.
the sample. As the data are skewed, the comparison made is between the median change in criminality, rather than the mean change. Levels of criminality fell over time across the whole DORIS sample, but there was no significant tendency for acquisitive crimes to fall faster among those receiving methadone treatment (and remaining in treatment) than in the rest of the sample.
Discussion It has proved difficult to retain recruited drug users into controlled trials of service effectiveness, because sample members who do not receive the treatment to which they aspire are likely to leave the trial and seek that treatment elsewhere. Thus cohort studies (comparing the post-treatment performance of drug users in a range of different treatment modalities) have become a frequent pragmatic alternative tool for evaluation of drug
user treatments and a major component of the evidence base on treatment effectiveness.3 DORIS, the largest ever cohort study of Scottish drug users, is one of a series of cohort studies (e.g. DATOS,17 NTORS18) designed to evaluate treatments for drug users. All such cohort studies are naturally subject to the difficulty that the treatment subpopulations of drug users being compared may not be equivalent. The difficulty is diminished but not eliminated by choosing (as in this paper) outcome measures that assess subpopulation changes rather than end states. A further difficulty is that drug users may go on to experience different treatment episodes in different treatment modalities subsequent to the baseline treatment episode. While data on subsequent treatments have been collected in the DORIS study, it has proved impossible to disaggregate the sample into subpopulations which both faithfully reflect similarities in postrecruitment treatment careers and are of sufficient size for statistical analysis.
Table 4 Changes in days when acquisitive crimes were reported among those still receiving methadone maintenance.
Change in days committing acquisitive crimes (DORIS1eDORIS4) Change in days arrested for acquisitive crimes (DORIS1eDORIS4)
Baseline treatment: methadone maintenance and still in contact with agency (n ¼ 46)
All other (non-prison) treatments (n ¼ 364)
P-value (Mann-Whitney)
Median (interquartile range)
Median (interquartile range)
4 (0e13)
5 (0e56.5)
0.5219
3 (1e8)
9 (0e62)
0.5622
1018 Accordingly, this study has followed past practice in cohort studies and compared outcomes only in respect of differences in baseline treatments. This study is also based (again reflecting past research practice) on self-reported data for both drug use and criminality. There was close concordance between self-reported data and oral fluid testing at DORIS1, and there is no reason to suppose that any tendency to under-report criminality would vary systematically between methadonemaintained patients and other treatment groups; the accuracy of the self-reported DORIS data on criminality is also discussed elsewhere.19 A final caveat to consider is the possibility that patterns of methadone-maintenance provision in Scotland may have changed in important ways since sample recruitment in 2001. Bearing these points in mind, these data appear to indicate that methadone-maintenance services have one valuable advantage over other services. Methadone-maintenance clients are not more likely to achieve abstinence than other clients; that distinction goes to clients of residential rehabilitation services.20 Nor are methadone-maintenance clients more likely to reduce their level of drug dependence relative to clients of other services. However, they are significantly more likely to achieve a reduction in the frequency of their illicit drug use; they ‘top-up’ on methadone, but the frequency of their illicit drug use in ‘topping up’ is less than that of drug users who have been clients in other drug treatment modalities. It might be supposed that higher doses of methadone would result in a reduced propensity to ‘top-up’ with heroin, but this propensity was not observed in the study data. The observed reduction in frequency of illicit drug use among methadone-maintained clients has been noted in other studies to be associated with reduced levels of criminality,18 but this was not observed in the present study. It remains possible that both dose effects and disproportionate changes in criminality may have been found in a larger methadone-maintained sample. Of course, there are public health benefits consequent on reductions in the frequency of heroin use. These would be more substantial if there were an additional propensity for methadone-maintenance clients to achieve abstinence in the longer term, but the study data indicate no significant difference in achievement of abstinence from heroin between methadone-maintained clients and clients of other services when grouped. These data confirm the value of methadone-maintenance services as part of a ‘mixed economy’ of services for the treatment of drug use.
M. Bloor et al.
Acknowledgements The authors wish to thank all members of the DORIS research team and all study participants.
Ethical approval Multicentre Research Ethics Committee Scotland, Ref. WH/MREC/01/0/33.
for
Funding The Robertson Trust and the Scottish Executive.
Competing interests None declared.
References 1. Neale J. Drug users in society. Basingstoke: Palgrave; 2002. 199. 2. Hunt N. A review of the evidence-base for harm reduction approaches to drug use. London: Forward Thinking on Drugs. Available from: http://forward-thinking-on-drugs. org/review2.html; 2003 [accessed 22.01.07]. 3. Department of Health. Drug misuse and dependence e guidelines on clinical management. London: Stationery Office; 1999. 4. Strang J, Gossop M, editors. Heroin addiction and the British system: treatment and other responses, vol. 2. London: Routledge; 2004. 5. Hall W, Ward J, Mattick P. Introduction. In: Ward J, Mattick R, Hall R, editors. Methadone maintenance treatment and other opioid replacement therapies. Amsterdam: Harwood; 1998. 6. Strang J, Manning V, Mayet S, Ridge G, Best D, Sheridan J. Does prescribing for opiate addiction change after national guidelines? Methadone and buprenorphine prescribing to opiate addicts by general practitioners and hospital doctors in England, 1995e2005. Addiction 2007;102:761e70. 7. Newman R, Whitehill W. Double blind comparison of methadone and placebo maintenance treatment of narcotic addicts in Hong Kong. Lancet 1979;ii:485e8. 8. Farrell M, Ward J, Mattick R, Hall W, Stimson G, Des Jarlais D, et al. Methadone maintenance treatment in opiate dependence: a review. BMJ 1994;309:997e1001. 9. Marsch L. The efficacy of methadone maintenance interventions in reducing illicit opiate use, HIV risk behaviour and criminality: a meta-analysis. Addiction 1998;93:515e32. 10. Luty J, O’Gara C, Sessay M. Editorial: is methadone too dangerous for opiate addiction? BMJ 2005;331:1352e3. 11. Raffa J, Grebely J, Tossonian H, Wong T, Viljoen M, Khara M, et al. The impact of ongoing illicit drug use on methadone adherence in illicit drug users receiving treatment for HIV in a directly observed therapy programme. Drug Alcohol Depend 2007;89:306e9. 12. Neale J, Robertson M. Recent life problems and non-fatal overdose among heroin users entering treatment. Addiction 2005;100:168e75.
Patterns of heroin use among Scottish drug users 13. Neale J, Robertson M. Comparisons of self-report data and oral fluid testing in detecting drug use among new treatment clients. Drug Alcohol Depend 2005;71:57e64. 14. Gossop M, Darke S, Griffiths P, Marsden J, Stewart D. The Severity of Dependence Scale (SDS): psychometric properties of the SDS in English and Australian samples of heroin, cocaine and amphetamine users. Addiction 1995;90:607e14. 15. McIntosh J, Bloor M, Robertson M. The health benefits of reductions in individuals’ use of illegal drugs. J Subst Use, in press. 16. Strain E, Stitzer M, Liebson I, Bigelow G. Dose response effects of methadone in the treatment of opioid dependence. Ann Intern Med 1993;119:23e37. 17. Anglin M, Hser Y, Grella C. Drug addiction and treatment careers among clients in the Drug Abuse Treatment
1019 Outcome Study (DATOS). Psychol Addict Behav 1997;11: 308e23. 18. Gossop M, Marsden J, Stewart D, Treacy S. Outcomes after methadone maintenance and methadone reduction treatments: two year follow-up results from the National Treatment Outcome Research Study. Drug Alcohol Depend 2001; 62:255e64. 19. McIntosh J, Bloor M, Robertson M. The effect of drug treatment upon the commission of acquisitive crime. J Subst Use 2007;12:375e84. 20. McKeganey N, Bloor M, Robertson M, Neale J. Abstinence and drug abuse treatment in Scotland: results from the Drug Outcome Research in Scotland study. Drugs Educ Prev Policy 2006;13:537e51.
Available online at www.sciencedirect.com
www.elsevierhealth.com/journals/pubh
Original Research
‘Topping up’ methadone: An analysis of patterns of heroin use among a treatment sample of Scottish drug users M. Bloora,*, J. McIntosha, N. McKeganeya, M. Robertsonb a
Centre for Drug Misuse Research, University of Glasgow, 89 Dumbarton Road, Glasgow G11 6PW, UK Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK
b
Received 14 February 2007; received in revised form 29 November 2007; accepted 30 January 2008 Available online 19 May 2008
KEYWORDS Methadone maintenance; Drug use; Cohort study
Summary Objectives: To determine: (a) whether Scottish drug users on methadone maintenance use heroin less frequently than their peers following other forms of drug treatment; and (b) to what extent those on methadone maintenance ‘top up’ with heroin. Design: A cohort study followed-up for 33 months from 2001 to 2004. Methods: Four hundred and ten interviewees who responded at all four interview sweeps, recruited as new treatment entrants from 28 drug treatment agencies across Scotland. Results: Sixty-eight of the 401 interviewees had commenced an episode of methadone-maintenance treatment at the start of the study. There was no significant difference between the methadone-maintained sample and the other interviewees in their propensity to abstain from heroin use, nor was there any difference between the two groups in the mean reduction over time in their self-reported dependence on drugs. However, if the outcome measure used is the change (between baseline and 33 months) in the number of days that the interviewee reported having used heroin in the previous 3 months, the reduction in the number of days that heroin was used was significantly greater (52 days) in the methadone-maintained group than in the rest of the sample (36.4 days). This fall in the number of days of heroin use was greater still if the comparison was restricted to those who had continued on methadone-maintenance treatment, although 67.4% of those still on methadone maintenance had ‘topped up’ with heroin at some point in the 3 months prior to 33-month follow-up. Those on higher maintenance doses were not significantly more likely to have reduced the number of days on which they used heroin compared with those on lower doses, and those still on methadone maintenance were not more likely to have reduced their criminality (measured by the number of days on which they committed acquisitive crimes in the previous 3 months) compared with the rest of the sample.
* Corresponding author. Tel.: þ44 (0) 141 330 2670; fax: þ44 (0) 141 330 2820. E-mail address: [email protected] (M. Bloor). 0033-3506/$ - see front matter ª 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.puhe.2008.01.007
1014
M. Bloor et al. Conclusions: Methadone-maintained drug users are not more likely to achieve abstinence than drug users receiving other forms of treatment, but they are significantly more likely to achieve a reduction in the frequency of their illicit drug use; they ‘top up’ on methadone, but the frequency of their illicit drug use is less than that of drug users in other treatment modalities. These data confirm the value of methadone-maintenance services as part of a ‘mixed economy’ of services for the treatment of drug use. ª 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.
Introduction ‘They [the doctors] always think that if you don’t stick to your methadone and you’re still using smack [heroin] on top of it, then it’s not working. That’s not the case at all and I know that’s true for an awful lot of people. That is a very important point e methadone still works even if you’re abusing on top of it, because you can use it to stop yourself from getting in jail, to stop yourself from going out on the game, and to keep your children with you.’ The above quotation,1 from a drug user on methadone maintenance who still ‘topped up’ by intermittent heroin use, neatly encapsulates the counter-argument to those who would claim that substitute prescribing is ‘not working’ if drug users in treatment continue to use heroin. If heroin users are only ‘topping up’, the counter-argument goes, then their overall consumption of heroin is much reduced, their health risks are reduced and their criminality is reduced. This is an aspect of the broader ‘harm-reduction’ approach in drugs policy2 which promotes interventions to contain and ameliorate drug-related harms to individuals and the wider community, alongside the pragmatic recognition that interventions to eliminate drug use are unlikely to be wholly successful. Methadone maintenance is a central component of harm-reduction policies in the UK.3,4 It involves the administration (usually by a non-parenteral route and usually daily) of the long-acting (24e 36 h) opioid to an opioid-dependent person on a maintenance basis, in order to improve the health status and psychological and social well-being of the opiate-dependent person. Once improvement has occurred, patient and doctor may concur in moving to a progressively reducing dosage.5 Between 1995 and 2005, the number of substitute opiate prescriptions in England is estimated to have doubled, with 83% of them for methadone.6 The extensive research literature concentrates on
issues of treatment effectiveness in trials,7 reviews8 and meta-analyses,9 or on issues of treatment delivery.10 Although ‘topping up’ seems to be a frequent practice, its extensiveness has seldom been described. Raffa et al. reported that only four out of 60 patients in a Canadian methadone maintenance and HIV medication programme abstained from all illicit drug use.11 The present study aimed to estimate the extent, if any, to which drug users who ‘topped up’ were are using less illicit drugs than their peers who were not receiving substitute methadone prescribing.
Methods The Drug Outcome Research in Scotland (DORIS) study is a cohort study of 1007 drug users recruited in 33 drug treatment agencies (both community-based and prison-based) across Scotland in 2001/2002. The baseline treatment offered at sample recruitment was methadone (27%), other prescribed drugs (dihydrocodeine, diazepam, temazepam, lofexidine, MXL) (29%), residential detoxification (12%), residential rehabilitation (12%), counselling (14%) and group work (4%). Methadone treatment may be short term on a reducing dose, or longer term on a maintenance dose. In this study, baseline treatment was self-reported by the interviewee, rather than being defined by the service provider or the researcher. The mean methadone dose for those on methadone maintenance was 55.4 mg (median dose 50 mg, range 12e120 mg). This may be considered quite a low mean dose, as the UK guidelines for a maintenance dose are 60e120 mg3; however, it is comparable with the mean dose of 56.3 mg found in a large survey of pharmacies in England in 2005.6 Since very few prisoners in Scotland had access to methadone-maintenance treatment in 2001, the prison-recruited respondents have been excluded from these analyses. DORIS respondents were followed-up at 8 months (DORIS2), 16 months (DORIS3) and 33 months (DORIS4), with response
Patterns of heroin use among Scottish drug users rates of eligible respondents of 85%, 79% and 70%, respectively. The DORIS4 analyses were therefore conducted on those respondents recruited in community-based agencies and interviewed at all four sweeps (n ¼ 410, see Fig. 1). The sociodemographic profile of the DORIS respondents is comparable with the profile of returns made to the Scottish Drug Misuse Database of all drug users entering treatment in 2001.12 Sixty-nine percent of DORIS respondents were male and their mean age was 28 years. The 28 agencies, other than prisons, from which DORIS respondents were recruited included 19 community drug agencies, five residential drug treatment agencies (both detoxification and rehabilitation agencies), three general practices and one pharmacy. The first 275 DORIS respondents were asked to provide oral fluid samples for drug testing. Concordance with reporting was 94% for methadone, 86% for opiates, 81% for benzodiazepines and 80% for cannabis, with testing failing to identify reported drug use more often than unreported drug use.13 The great majority of respondents were polydrug users, but 81% reported that their main drug was heroin, with 5% citing diazepam, 5% citing methadone, 3% citing cannabis and less than 2% citing either cocaine, crack, dihydrocodeine, amphetamine, buprenorphine or ecstasy as their main drug. Logistic regression analysis of attrition bias at DORIS4 showed that differential attrition had only occurred in respect of two variables; being a prisoner and being homeless at DORIS1. DORIS1 (1007 respondents)
Deaths and lost to follow-up (n=354)
DORIS respondents to all four sweeps (n=653)
Prison-based treatment (n=252) Treatment outside prison (n=410)
Other non-prison treatments (n=342) Methadone-maintenance treatment (n=68)
Figure 1
The DORIS sample.
1015 Interviews were unnamed and voluntary and took between 1 and 2 h. Ethical oversight was exercised by the Scottish Multicentre Research Ethics Committee. The standard instruments used had been developed and validated in other studies; the measure of self-reported drug dependence was developed specifically for use with drug treatment populations, including methadone-maintained patients.14 More detailed reports of the study methods have been published elsewhere,12 as have reports of other DORIS study outcomes such as changes in health status.15
Results Sixty-eight of the 401 DORIS interviewees at 33month follow-up were receiving methadone maintenance as baseline treatment. If one takes as a measure of performance, whether or not the interviewee had ever used heroin in the 3 months prior to interview, 21 (30.9%) of those on methadone maintenance had improved over the 33 months, compared with 140 (40.9%) of those on other treatments; this difference was not significant (Chi-squared test: P ¼ 0.1210). Likewise, if one takes change in severity of dependence scores as a measure of performance, the fall in mean score over the 33 months in the interviewees receiving methadone maintenance was not significantly different from the fall in mean score among those receiving other forms of treatment (Table 1). However, Table 1 also shows performance as measured by change in the number of days in which they had used heroin in the last 3 months. Between baseline and 33 month followup, the average fall in the number of days that interviewees used heroin was 52 for those on methadone maintenance at baseline, compared with 36.4 days for those receiving other treatments. Many of those who had received methadone maintenance were ‘topping up’ with heroin, but they were using heroin on significantly fewer days than those who had undergone different treatments. This relative advantage that methadone maintenance has over other treatments, in changed frequency of heroin use, is more apparent still if one compares, not those who started on methadone maintenance (68 interviewees) with the rest of the sample, but rather those who remained in methadone-maintenance treatment (46 interviewees) with the rest of the sample. No significant difference was found between the two treatment groups in changes in those who had ever used heroin in the last 3 months; 15 (32.6%) of those on methadone maintenance had improved compared
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M. Bloor et al.
Table 1 Changes in frequency of heroin use and in dependence score among those receiving methadone maintenance at baseline.
Change in SD (dependence) score (DORIS1eDORIS4) Change in days when used heroin in the last 3 months (DORIS1eDORIS4)
Baseline treatment: methadone maintenance (n ¼ 68)
All other (non-prison) treatments (n ¼ 342)
P-value (two-sample t-test)
Mean (SD)
Mean (SD)
5.1 (4.6)
4.8 (5.6)
0.6988
52.0 (41.7)
36.4 (41.5)
0.0050
SD, standard deviation.
with 146 (40.1%) among the rest (Chi-squared test: P ¼ 0.3263). Table 2 shows no significant difference in changes in dependence scores between the two groups (P ¼ 0.7523). However, the mean fall in the number of days using heroin was 57.2 among those starting methadone maintenance at baseline who were still in contact with the treatment agency, compared with 36.7 days for the rest of the sample (P ¼ 0.0017). For those still on methadone maintenance 33 months later, the mean number of days on which they had used heroin in the last 3 months was 17.6 days, compared with 22.6 days for the rest of the sample; the median number of days was 3. Other studies have found that higher doses are more treatment effective,16 so it was relevant to establish whether or not those interviewees on relatively high doses showed the greatest reductions in frequency of use. Due to small subsample sizes, this comparison is only shown for changes in dependence score and frequency of heroin use between DORIS1 and DORIS2 (an 8-month period, rather than a 33-month period). Again, no significant difference was observed between those on higher and lower maintenance doses in changes in whether they had ever used heroin in the last
3 months; 12 (54.5%) of the 22 interviewees on higher doses had improved, compared with 51 (66.2%) interviewees on lower doses (Chi-squared test: P ¼ 0.3149). Table 4 compares the performances of those receiving high doses of methadone (more than one standard deviation above the mean, i.e. 79.4 mg) with those receiving lower doses, in respect of changes in dependence scores and changes in frequency of heroin use. As in Tables 1 and 2, no significant differences were found in respect of changes in dependence scores in Table 3 (P ¼ 0.5854). Those on higher doses did report a slightly larger fall in the frequency of heroin use (57.8 days vs 48.0 days), but this was not significant (P ¼ 0.2781). Table 4 shows changes between baseline and DORIS4 in self-reported criminality, in terms of changes in the number of days on which interviewees reported that they committed acquisitive crimes (defined as drug dealing, house breaking, shop lifting and thefts from persons) and changes in the number of days on which interviewees reported that they had been arrested for acquisitive crimes. The comparison made is between those methadone-maintenance interviewees still in contact with their treatment agency and the rest of
Table 2 Changes in frequency of heroin use and in dependence score among those receiving methadone maintenance at baseline and still in contact with the treatment agency.
Change in SD (dependence) score (DORIS1eDORIS4) Change in days when used heroin in the last 3 months (DORIS1eDORIS4) SD, standard deviation.
P-value (two-sample t-test)
Baseline treatment: methadone maintenance and still in contact with agency (n ¼ 46)
All other (non-prison) treatments (n ¼ 364)
Mean (SD)
Mean (SD)
5.1 (4.6)
4.8 (5.5)
0.7523
57.2 (35.9)
36.7 (42.0)
0.0017
Patterns of heroin use among Scottish drug users
1017
Table 3 Changes in frequency of heroin use and in dependence score among those receiving high methadonemaintenance doses versus others on maintenance doses.
Change in SDS (dependence) score (DORIS1eDORIS2) Change in days when used heroin in the last 3 months (DORIS1eDORIS2)
P-value (two-sample t-test)
Baseline treatment: methadone maintenance and methadone dose more than 1 SD above the mean (n ¼ 22)
Baseline treatment: methadone maintenance and methadone dose less than 1 SD above the mean (n ¼ 77)
Mean (SD)
Mean (SD)
5.9 (4.0)
5.3 (4.8)
0.5854
57.8 (37.9)
48.0 (36.8)
0.2781
SD, standard deviation.
the sample. As the data are skewed, the comparison made is between the median change in criminality, rather than the mean change. Levels of criminality fell over time across the whole DORIS sample, but there was no significant tendency for acquisitive crimes to fall faster among those receiving methadone treatment (and remaining in treatment) than in the rest of the sample.
Discussion It has proved difficult to retain recruited drug users into controlled trials of service effectiveness, because sample members who do not receive the treatment to which they aspire are likely to leave the trial and seek that treatment elsewhere. Thus cohort studies (comparing the post-treatment performance of drug users in a range of different treatment modalities) have become a frequent pragmatic alternative tool for evaluation of drug
user treatments and a major component of the evidence base on treatment effectiveness.3 DORIS, the largest ever cohort study of Scottish drug users, is one of a series of cohort studies (e.g. DATOS,17 NTORS18) designed to evaluate treatments for drug users. All such cohort studies are naturally subject to the difficulty that the treatment subpopulations of drug users being compared may not be equivalent. The difficulty is diminished but not eliminated by choosing (as in this paper) outcome measures that assess subpopulation changes rather than end states. A further difficulty is that drug users may go on to experience different treatment episodes in different treatment modalities subsequent to the baseline treatment episode. While data on subsequent treatments have been collected in the DORIS study, it has proved impossible to disaggregate the sample into subpopulations which both faithfully reflect similarities in postrecruitment treatment careers and are of sufficient size for statistical analysis.
Table 4 Changes in days when acquisitive crimes were reported among those still receiving methadone maintenance.
Change in days committing acquisitive crimes (DORIS1eDORIS4) Change in days arrested for acquisitive crimes (DORIS1eDORIS4)
Baseline treatment: methadone maintenance and still in contact with agency (n ¼ 46)
All other (non-prison) treatments (n ¼ 364)
P-value (Mann-Whitney)
Median (interquartile range)
Median (interquartile range)
4 (0e13)
5 (0e56.5)
0.5219
3 (1e8)
9 (0e62)
0.5622
1018 Accordingly, this study has followed past practice in cohort studies and compared outcomes only in respect of differences in baseline treatments. This study is also based (again reflecting past research practice) on self-reported data for both drug use and criminality. There was close concordance between self-reported data and oral fluid testing at DORIS1, and there is no reason to suppose that any tendency to under-report criminality would vary systematically between methadonemaintained patients and other treatment groups; the accuracy of the self-reported DORIS data on criminality is also discussed elsewhere.19 A final caveat to consider is the possibility that patterns of methadone-maintenance provision in Scotland may have changed in important ways since sample recruitment in 2001. Bearing these points in mind, these data appear to indicate that methadone-maintenance services have one valuable advantage over other services. Methadone-maintenance clients are not more likely to achieve abstinence than other clients; that distinction goes to clients of residential rehabilitation services.20 Nor are methadone-maintenance clients more likely to reduce their level of drug dependence relative to clients of other services. However, they are significantly more likely to achieve a reduction in the frequency of their illicit drug use; they ‘top-up’ on methadone, but the frequency of their illicit drug use in ‘topping up’ is less than that of drug users who have been clients in other drug treatment modalities. It might be supposed that higher doses of methadone would result in a reduced propensity to ‘top-up’ with heroin, but this propensity was not observed in the study data. The observed reduction in frequency of illicit drug use among methadone-maintained clients has been noted in other studies to be associated with reduced levels of criminality,18 but this was not observed in the present study. It remains possible that both dose effects and disproportionate changes in criminality may have been found in a larger methadone-maintained sample. Of course, there are public health benefits consequent on reductions in the frequency of heroin use. These would be more substantial if there were an additional propensity for methadone-maintenance clients to achieve abstinence in the longer term, but the study data indicate no significant difference in achievement of abstinence from heroin between methadone-maintained clients and clients of other services when grouped. These data confirm the value of methadone-maintenance services as part of a ‘mixed economy’ of services for the treatment of drug use.
M. Bloor et al.
Acknowledgements The authors wish to thank all members of the DORIS research team and all study participants.
Ethical approval Multicentre Research Ethics Committee Scotland, Ref. WH/MREC/01/0/33.
for
Funding The Robertson Trust and the Scottish Executive.
Competing interests None declared.
References 1. Neale J. Drug users in society. Basingstoke: Palgrave; 2002. 199. 2. Hunt N. A review of the evidence-base for harm reduction approaches to drug use. London: Forward Thinking on Drugs. Available from: http://forward-thinking-on-drugs. org/review2.html; 2003 [accessed 22.01.07]. 3. Department of Health. Drug misuse and dependence e guidelines on clinical management. London: Stationery Office; 1999. 4. Strang J, Gossop M, editors. Heroin addiction and the British system: treatment and other responses, vol. 2. London: Routledge; 2004. 5. Hall W, Ward J, Mattick P. Introduction. In: Ward J, Mattick R, Hall R, editors. Methadone maintenance treatment and other opioid replacement therapies. Amsterdam: Harwood; 1998. 6. Strang J, Manning V, Mayet S, Ridge G, Best D, Sheridan J. Does prescribing for opiate addiction change after national guidelines? Methadone and buprenorphine prescribing to opiate addicts by general practitioners and hospital doctors in England, 1995e2005. Addiction 2007;102:761e70. 7. Newman R, Whitehill W. Double blind comparison of methadone and placebo maintenance treatment of narcotic addicts in Hong Kong. Lancet 1979;ii:485e8. 8. Farrell M, Ward J, Mattick R, Hall W, Stimson G, Des Jarlais D, et al. Methadone maintenance treatment in opiate dependence: a review. BMJ 1994;309:997e1001. 9. Marsch L. The efficacy of methadone maintenance interventions in reducing illicit opiate use, HIV risk behaviour and criminality: a meta-analysis. Addiction 1998;93:515e32. 10. Luty J, O’Gara C, Sessay M. Editorial: is methadone too dangerous for opiate addiction? BMJ 2005;331:1352e3. 11. Raffa J, Grebely J, Tossonian H, Wong T, Viljoen M, Khara M, et al. The impact of ongoing illicit drug use on methadone adherence in illicit drug users receiving treatment for HIV in a directly observed therapy programme. Drug Alcohol Depend 2007;89:306e9. 12. Neale J, Robertson M. Recent life problems and non-fatal overdose among heroin users entering treatment. Addiction 2005;100:168e75.
Patterns of heroin use among Scottish drug users 13. Neale J, Robertson M. Comparisons of self-report data and oral fluid testing in detecting drug use among new treatment clients. Drug Alcohol Depend 2005;71:57e64. 14. Gossop M, Darke S, Griffiths P, Marsden J, Stewart D. The Severity of Dependence Scale (SDS): psychometric properties of the SDS in English and Australian samples of heroin, cocaine and amphetamine users. Addiction 1995;90:607e14. 15. McIntosh J, Bloor M, Robertson M. The health benefits of reductions in individuals’ use of illegal drugs. J Subst Use, in press. 16. Strain E, Stitzer M, Liebson I, Bigelow G. Dose response effects of methadone in the treatment of opioid dependence. Ann Intern Med 1993;119:23e37. 17. Anglin M, Hser Y, Grella C. Drug addiction and treatment careers among clients in the Drug Abuse Treatment
1019 Outcome Study (DATOS). Psychol Addict Behav 1997;11: 308e23. 18. Gossop M, Marsden J, Stewart D, Treacy S. Outcomes after methadone maintenance and methadone reduction treatments: two year follow-up results from the National Treatment Outcome Research Study. Drug Alcohol Depend 2001; 62:255e64. 19. McIntosh J, Bloor M, Robertson M. The effect of drug treatment upon the commission of acquisitive crime. J Subst Use 2007;12:375e84. 20. McKeganey N, Bloor M, Robertson M, Neale J. Abstinence and drug abuse treatment in Scotland: results from the Drug Outcome Research in Scotland study. Drugs Educ Prev Policy 2006;13:537e51.
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