Cost-effectiveness of interventions to reduce harm from amphetamine/methamphetamine use

Abstract

Abstract Illicit methamphetamine (MA) use is an important public health concern in Australia. MA use is associated with increased health care and criminal justice spending (due to criminal activity associated with addiction). Current knowledge about effective and cost-effective treatments in Australia is limited and there is a clear need to determine the cost-effectiveness of treatment options for MA dependence. This thesis describes the economic evaluation of two community-based treatment programs for MA users. More specifically, this work evaluates the cost-effectiveness of counselling as an outpatient treatment modality and residential rehabilitation as an inpatient treatment modality for MA users, compared with no treatment. This thesis will also assess other criteria, including ‘second filter’ criteria, which may influence policy decisions about current treatment programs in the community. A cost-effectiveness framework was applied to newly available data from Australia – namely, the Methamphetamine Treatment Evaluation Study (MATES) conducted by the National Drug and Alcohol Research Centre (NDARC) of the University of New South Wales. In doing so, the health and cost outcomes associated with the two different treatment options and the non-treatment comparison group of MA users were identified. Both models, as used in the analysis of cost and health outcomes, feature a decision-tree type of models with each decision being a final decision in the decision tree node. Health–Related Quality of Life (HRQL) outcomes were obtained using the SF-6D algorithm to translate responses from the SF-12 Health Questionnaire used in MATES into a single preference-based utility score. The HRQL showed a statistically significant improvement at both 3 and 12 months follow-up compared with baseline among MATES participants for both groups. The HRQL for the residential treatment group was of greater magnitude than the other groups. The cost outcomes were evaluated on the basis of social perspective. Costs measured include treatment, crime, and health service utilisation costs. The analysis of cost and health outcomes (base case scenario discounted at 3% social preference rate and with all costs included in the analysis) indicated a difference in Quality-Adjusted Life Years, ∆QALY = 107 QALYs, costs difference of ∆Costs = -AU$18,364,110, and incremental cost-effectiveness ratio (ICER), ∆C/∆QALY, as dominant for counselling treatment modality compared with no treatment. Cost-effectiveness analysis of residential rehabilitation treatment modality compared with no treatment option indicates a QALY difference, ∆QALY = 68, difference in costs of ∆Costs = AU$1,301,630, and an ICER = AU$23,752 per QALY. Therefore, both interventions meet the cost-effectiveness criterion for cost-effectiveness (threshold below AU$76,000 per QALY), recommended by the Pharmaceutical Benefits Advisory Committee (PBAC) of Australia. The results of uncertainty analysis show the outcomes of the analysis given uncertainty surrounding parameter inputs in the model. Also, sensitivity analysis tested for major cost drivers in the model. Second stage filter criteria are used to address criteria other than cost-effectiveness for the two treatment options. The results of uncertainty analyses suggest that both interventions, counselling and residential rehabilitation when compared with no intervention and under given modelling limitations, are cost-effective strategies for managing the problems of MA dependence in Australian society. Even when different scenarios are considered in various uncertainty analyses, the ICER is either dominant or below the threshold of AU$76,000 per QALY for both interventions when compared with no intervention alternative. The results of sensitivity analyses for both interventions compared with no intervention suggest that costs of crime are major cost drivers for interventions, counselling compared with no intervention and residential rehabilitation compared with no intervention. The results suggest that policy changes towards interventions to reduce current harms in the society as well as on the individual level of users’ dependence are warranted. Firstly, more attention should be given to community treatment services that treat majority of MA users in Australia. Secondly, within the current treatment services for MA dependence in Australia, psychosocial forms of treatment such as counselling and residential rehabilitation treatments should be applied before other interventions are introduced. Thirdly, considerable savings in the Australian society are able to be achieved through the implementation of these two treatment modalities due to lower spending in the criminal justice sector after the application of treatment among MA users. The policy related implementation of the results of this study in the Australian society needs to be considered with caution in relation to the issue of efficacy versus effectiveness, i.e. findings of this study as compared to population wide impact and outcomes. Policy makers should recommend increased funding for the services providing community treatment services for MA users as this would effectively translate the results of this study into better results on cost and health outcomes on population level. Further policy related findings show that the implementation of both interventions, counselling and residential rehabilitation compared with a non-treatment option is suitable for the following reasons: (i) reduction of current inequities among MA users in the community; (ii) acceptance to stakeholders; (iii) feasibility of implementation; (iv) sustainability of the interventions; and (v) the potential for side effects is minimal for both interventions. This thesis demonstrates the cost-effectiveness of two treatment modalities for MA dependence in Australia in a transparent, standardised and evidence-based way. The findings can be used to inform policy-makers about how to better allocate resources and drive better policy decisions for treatment options for MA dependence