Evaluation of the cost-effectiveness of buprenorphine in treatment of chronic pain using competing EQ-5D weights.

Background and aims Chronic pain is a life altering condition and common among elderly persons. The 7-day buprenorphine patch could be a suitable treatment for managing chronic pain of moderate severity in elderly patients in Sweden. The objective of this analysis was to investigate the cost-effectiveness of the 7-day buprenorphine patch, versus no treatment, in patients >50 years old who suffer from moderate pain in a health economic perspective. An additional aim was to evaluate how the cost-effectiveness is affected by the choice of EQ-5D weights. Methods The annual treatment cost and the potential gains in health-related quality of life (HRQoL) of buprenorphine, compared to no treatment, were evaluated. Original EQ-5D data were collected from four clinical reference studies at baseline and at the final visit. Treatment effects on HRQoL were then assessed using both UK and Swedish EQ-5D weights. Annual treatment costs were calculated based on costs of physician visits and pharmaceuticals. The optimal treatment dose was 10-15 μg/h and the analysis was hence performed on both a 10- and a 15 μg/h buprenorphine patch. Results The analysis of buprenorphine treatment resulted in improved HRQoL in all reference studies, irrespective of choice of EQ-5D weight set. The change in quality adjusted life years (QALYs) varied with a gain of 0.042-0.118 using the UK weights and 0.020-0.051 with the Swedish weights. The average annual treatment cost was SEK14454 for the 10μg/h patch and SEK17 017 for the 15 μg/h patch, while cost for the no-treatment alternative was SEK 9 960. The base case incremental cost-effectiveness ratios (ICER) with the UK weights were SEK 40000-SEK 170000 and SEK 90000-SEK 350000 when applying the Swedish weights. The corresponding ICER-span in the sensitivity analysis was SEK 15 000-SEK 400 000 when applying the UK weights and SEK 30 000-SEK 840 000 with the Swedish weights (SEK 100 is about €11). Conclusions The results imply that the 7-day buprenorphine patch may be a cost-effective treatment of moderate chronic pain in patients over 50 years of age. The UK and the Swedish EQ-5D weights generated vastly different HRQoL estimates but buprenorphine remains cost-effective regardless choice of weight set.