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

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.

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 €10.000/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.

Keywords: Abdominal pain; ICER; QALY; cost-effectiveness; economic burden; irritable bowel syndrome; peppermint oil.

FIGURE 1

Cost‐effectiveness plane of small‐intestinal release peppermint oil compared with placebo. Each data‐point represents one bootstrapped estimate of incremental costs and baseline corrected quality adjusted life years. The bootstrapped incremental cost‐effectiveness ratios cover all four quadrants in both planes, indicating some uncertainty of the data. 46% of simulations lie in the south‐east quadrant, the quadrant indicating dominance of peppermint oil. 31% of simulations lie in the north‐east quadrant, indicating higher efficacy but at higher cost. The cost‐effectiveness acceptability curve (Figure 2) shows the probability peppermint oil is cost‐effective at different willingness to pay‐thresholds

FIGURE 2

Cost‐effectiveness acceptability curve. The line indicates the probability (y‐axis) of a treatment being cost‐effective, that is, the proportion of replications small‐intestinal release peppermint oil has the highest net monetary benefit, given various levels of willingness to pay (cost‐effectiveness thresholds (x‐axis)

FIGURE 3

Cost‐effectiveness acceptability curve of costs and abdominal pain responder (food and drug administration definition). The line indicates the probability (y‐axis) of small‐intestinal release peppermint oil being cost‐effective. At a WTP‐threshold of 5.000, small‐intestinal release has a probability of 89% of being cost effective when using the main clinical parameter, abdominal pain responder, as effect outcome