Tramadol and the risk of fracture in an elderly female population: a cost utility assessment with comparison to transdermal buprenorphine
Introduction Opioid treatment for chronic pain is a known risk factor for falls and/or fractures in elderly patients. The latter cause a significant cost to the National Health Service and the Personal Social Services in the UK. Tramadol has a higher risk of fractures than some other opioid analgesics used to treat moderate-to-severe pain and, in the model described here, we investigate the cost effectiveness of transdermal buprenorphine treatment compared with tramadol in a high-risk population. Methods A model was developed to assess the cost effectiveness of tramadol compared with transdermal buprenorphine over a 1-year time horizon and a patient population of high-risk patients (female patients age 75 or older). To estimate the total cost and quality-adjusted life years (QALYs) of treatment, published odds ratios are used in combination with the published incidence rates of four types of fracture: hip, wrist, humerus and other. Results The model shows tramadol to be associated with 1,058 more fractures per 100,000 patients per year compared with transdermal buprenorphine, resulting in transdermal buprenorphine being cost-effective with an incremental cost-effectiveness ratio of less than £7,000 compared with tramadol. Sensitivity analysis found this result to be robust. Limitations In the UK data, there is uncertainty regarding the transdermal buprenorphine odds ratios for fractures. Odds ratios published in Danish and Swedish studies show similar point estimates but are associated with less uncertainty. Conclusion Transdermal buprenorphine is cost-effective compared to tramadol at a willingness-to-pay threshold of £20,000 per QALY.