Cost-Effectiveness of Duloxetine in Chronic Low Back Pain A Quebec Societal Perspective

Study Design. Cost-effectiveness model from a Quebec societal perspective using meta-analyses of clinical trials. Objective. To evaluate the cost-effectiveness of duloxetine in chronic low back pain (CLBP) compared with other post-first-line oral medications. Summary of Background Data. Duloxetine has recently received a CLBP indication in Canada. The cost-effectiveness of duloxetine and other oral medications has not previously been evaluated for CLBP. Methods. A Markov model was created on the basis of the economic model documented in the 2008 osteoarthritis clinical guidelines of the National Institute for Health and Clinical Excellence. Treatment-specific utilities were estimated via a meta-analysis of CLBP clinical trials and a transfer-to-utility regression estimated from duloxetine CLBP trial data. Adverse event rates of comparator treatments were taken from the National Institute for Health and Clinical Excellence model or estimated by a meta-analysis of clinical trials in osteoarthritis using a maximum-likelihood simulation technique. Costs were developed primarily from Quebec and Ontario public sources as well as the published literature and expert opinion. The 6 comparators were celecoxib, naproxen, amitriptyline, pregabalin, hydromorphone, and oxycodone. Subgroup analyses and 1-way and probabilistic sensitivity analyses were performed. Results. In the base case, naproxen, celecoxib, and duloxetine were on the cost-effectiveness frontier, with naproxen the least expensive medication, celecoxib with an incremental cost-effectiveness ratio of $19,881, and duloxetine with an incremental cost-effectiveness ratio of $43,437. Other comparators were dominated. Key drivers included the rates of cardiovascular and gastrointestinal adverse events and proton pump inhibitor usage. In subgroup analysis, the incremental cost-effectiveness ratio for duloxetine fell to $21,567 for a population 65 years or older and to $18,726 for a population at higher risk of cardiovascular and gastrointestinal adverse events. Conclusion. The model estimates that duloxetine is a moderately cost-effective treatment for CLBP, becoming more cost-effective for populations older than 65 years or at greater risk of cardiovascular and gastrointestinal events.