Zsa Zsa Weerts

Chapter 8 190 Abstract Background Irritable Bowel Syndrome (IBS) is a prevalent, chronic gastrointestinal disorder that imposes a substantial socioeconomic burden. Peppermint oil is a frequently used treatment for IBS, but evidence about cost-effectiveness is lacking. The objective of this trial-based economic evaluation was to assess the cost-effectiveness of small-intestinal release peppermint oil versus placebo in patients with IBS. Methods In a multicenter randomized placebo-controlled trial, cost-effectiveness was evaluated from a societal perspective. The incremental cost-effectiveness ratios were expressed as 1) incremental costs per Quality Adjusted Life Years (QALY), and 2) incremental costs per successfully treated patient, i.e. per abdominal pain responder (according to FDA definitions), both after an eight-week treatment period with placebo versus peppermint oil. Cost-utility and uncertainty were estimated using non-parametric bootstrapping. Sensitivity analyses were performed to examine parameter uncertainty. Results The analysis comprised 126 patients ( N =64 placebo, N =62 small-intestinal release peppermint oil). Peppermint oil was a dominant treatment compared to placebo in 46% of bootstrap replications. Peppermint oil was also more effective but at higher cost in 31% of replications. The net benefit acceptability curve showed that peppermint oil has a 56% probability of being cost-effective at a conservative willingness-to-pay threshold of €10.000 per QALY. Peppermint oil was also a dominant treatment per additional successfully treated patient according to FDA definitions, i.e. in 51% of the bootstrap replications. In this case, the acceptability curve showed an 89% probability of being cost-effective Conclusion In patients with IBS, small-intestinal release peppermint oil appears to be a cost-effective treatment although there is uncertainty surrounding the ICER. When using abdominal pain responder as outcome measure for the ICER, peppermint oil has a high probability of being cost-effective. The use of peppermint oil, which is a low-cost treatment, can be justified by the modest QALY gains and slightly higher proportion of abdominal pain responders. More research and long-term data are necessary to confirm the cost- effectiveness of peppermint oil. NCT02716285