Cost Effectiveness of Etoricoxib versus Celecoxib and Non-Selective NSAIDS in the Treatment of Ankylosing Spondylitis

Objective : To evaluate the cost effectiveness of etoricoxib (90mg/day) relative to celecoxib (200 or 400mg/day), and the non-selective NSAIDs naproxen (1000mg/day) and diclofenac (150 mg/day) in the initial treatment of ankylosing spondylitis (AS) from the UK NHS perspective. Methods : A Bayesian cost-effectiveness model was developed to estimate the costs and benefits associated with initiating AS treatment with etoricoxib, celecoxib, diclofenac or naproxen. Efficacy, safety and medical resource and cost data were obtained from the literature. The obtained efficacy estimates were synthesized with a mixed treatment comparison meta-analysis. Treatment benefit and degree of disease activity, as reflected with Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores, were related to QALYs and AS-specific costs (related to BASDAI). Other cost outcomes related to drug acquisition, and gastrointestinal and cardiovascular safety. Uncertainty in the source data was translated into uncertainty in cost-effectiveness estimates and therefore decision uncertainty. Costs and outcomes were discounted at 3.5% per annum. Results : There was a >98% probability that treatment with etoricoxib results in greater QALYs than the other interventions. Over a 30-year time horizon, starting AS treatment with etoricoxib was associated with about 0.4 more QALYs than the other interventions. At 2 years there was a 77% probability that etoricoxib had the lowest cost. This increased to >99% at 30 years. Etoricoxib is expected to save £13 620 (year 2007 values) relative to celecoxib (200/400 mg), £9957 relative to diclofenac and d9863 relative to naproxen. For a willingness-to-pay ceiling ratio of £20 000 per QALY, there was a >97% probability that etoricoxib was the most cost-effective treatment. Additional analysis with different assumptions, including celecoxib 200 mg, and ignoring cost-offsets associated with improvements in disease activity, supported these findings. Conclusions : This economic evaluation suggests that, from the UK NHS perspective, etoricoxib is the most cost-effective initial NSAID treatment for AS patients.