A trial-based economic evaluation of peppermint oil for the treatment of irritable bowel syndrome

Z.Z.R.M. Weerts*, B.A.B. Essers, D.M.A.E. Jonkers, J.I.A. Willems, D.J.P.A. Janssen, B.M. Witteman, C.H.M. Clemens, A. Westendorp, A.A.M. Masclee, D. Keszthelyi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


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. Objective We aimed to assess cost-effectiveness of small-intestinal release peppermint oil versus placebo in IBS patients. Methods In a multicenter randomized placebo-controlled trial, cost-effectiveness was evaluated from a societal perspective. The incremental cost-effectiveness ratios (ICERs) were expressed as (1) incremental costs per Quality Adjusted Life Years (QALY), and (2) incremental costs per successfully treated patient, that is 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. 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 euro10.000/QALY. Peppermint oil was also a dominant treatment per additional successfully treated patient according to FDA definitions, that is in 51% of replications. In this case, the acceptability curve showed an 89% probability of being cost-effective. Conclusions 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.
Original languageEnglish
Pages (from-to)997-1006
Number of pages10
JournalUnited European Gastroenterology Journal
Issue number9
Early online date1 Sept 2021
Publication statusPublished - Nov 2021


  • Abdominal pain
  • cost-effectiveness
  • economic burden
  • ICER
  • irritable bowel syndrome
  • peppermint oil
  • QALY
  • 12-WEEK
  • IBS


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