Buprenorphine versus methadone maintenance: a cost-effectiveness analysis

Abstract

This article presents the cost-effectiveness results of a randomised controlled trial conducted in two Australian cities. The trial was designed to assess the safety, efficacy and cost-effectiveness of buprenorphine versus methadone in the management of opioid dependence. The trial utilised a flexible dosing regime that was tailored to the clinical need of the patients, with high maximum doses, using the marketed formulation, under double-blind conditions. A total of 405 subjects were randomised to a treatment at one of three specialist outpatient drug treatment centres in Adelaide and Sydney, Australia. The perspective of the cost-effectiveness analysis was that of the service provider and included costs relevant to the provision of treatment. The primary outcome measure used in the economic analysis was change in heroin-free days from baseline to the sixth month of treatment. Treatment with methadone was found to be both less expensive and more effective than treatment with buprenorphine, which suggests methadone dominates buprenorphine. However, statistical testing found that the observed difference between the cost-effectiveness of methadone and buprenorphine treatments was not statistically significant. The results of this study provide useful policy information on the costs and outcomes associated with the use of methadone and buprenorphine and indicate that buprenorphine provides a viable alternative to methadone in the treatment of opioid dependence.

Introduction

Methadone maintenance treatment is the best-researched treatment for opioid dependence (Cooper et al., 1983, Gerstein and Harwood, 1990, Hargreaves, 1983, Mattick and Hall, 1993, Ward et al., 1998). Goldschmidt conducted the first economic evaluation of methadone treatment in the early 1970s. Methadone maintenance was as effective as a therapeutic community intervention, but with cost of providing methadone one-quarter the cost of therapeutic communities, methadone treatment was found to be twice as cost-effective (Goldschmidt, 1976). In a recent review of the literature on cost–benefit analysis of drug treatment, Cartwright (2000) identified a number of studies that calculated benefit cost ratios of methadone treatment and concluded that drug abuse treatment services, in general, provide positive economic returns to society. For example, Leslie (1971) calculated a benefit cost ratio of methadone treatment of 7.9, while Maidlow and Berman (1972) calculated a benefit cost ratio of methadone maintenance of 18.7. The most comprehensive cost–benefit analysis to date is that conducted by Gerstein and colleagues in 1994 in the Californian Drug and Alcohol Treatment Assessment (CALDATA) study. Gerstein et al. (1994) examined the effects of treatment—residential programs, residential “social model” programs, outpatient programs, and methadone programs—on alcohol and drug use, criminal activity, health and health care utilisation, and source of income. Cost of treatment and the economic value of treatment were also examined. Gerstein et al. (1994) found that for each modality of treatment the summed benefits from, during and after the first year of treatment significantly exceeded the cost of delivering the episode of care. For residential treatment the ratio of benefits to costs was 4.8. Comparable ratios were obtained for social model treatment and for continuing methadone. Much higher ratios of 11 to 1 and 12.6 to 1 were estimated for outpatient and discharged methadone participants.

Buprenorphine is a relatively new drug. It is a partial opioid agonist that, compared with methadone, appears to be safer in overdose, may have an easier withdrawal phase, and can be used as an alternate day dosing schedule in most patients (Mattick et al., 2002). A number of randomised clinical trials have reported that buprenorphine is as effective as methadone for use in maintenance therapy of opioid dependent patients (Johnson et al., 1992, Strain et al., 1994a, Strain et al., 1994b, Johnson et al., 2000, Pani et al., 2000). However, a similar number of studies have reported inferior results for buprenorphine (Kosten et al., 1993, Ling et al., 1996, Schottenfeld et al., 1997, Fischer et al., 1999, Petitjean et al., 2001). Usually, these latter authors attribute the inferiority of buprenorphine to doses of buprenorphine that are to low (Kosten et al., 1993, Ling et al., 1996, Schottenfeld et al., 1997, Fischer et al., 1999, Petitjean et al., 2001), or to slow induction onto low doses of buprenorphine (Uehlinger et al., 1998, Fischer et al., 1999).

While there is large number of studies on the relative effectiveness of methadone and buprenorphine as agents in the management of opioid dependence, there is little information on the relative economic impacts of these pharmacotherapies. This article presents the results of a cost-effectiveness analysis conducted alongside a randomised controlled trial that was designed to assess the safety and efficacy of buprenorphine versus methadone in the management of opioid dependence. The trial utilised a flexible dosing regime that was tailored to the clinical need of the patients, with high maximum doses, using the marketed tablet formulation, under double-blind conditions (Mattick et al., 2003).