Zsa Zsa Weerts

Chapter 8 192 informed consent prior to participation. Full details of the clinical trial have been published elsewhere 9 and are briefly summarized below. All authors had access to the study data and reviewed and approved the final manuscript. Patients, setting and interventions IBS patients, between 18 and 75 years of age were eligible for inclusion if they fulfilled the ROME IV criteria. 11 Patients had to have a mean daily worst abdominal pain score ≥3 during a two-week run-in period (on an eleven-point numerical rating scale (NRS)). Randomization was done with ALEA Screening and Enrollment software using the minimization method accounted for inclusion center, IBS subtypes, gender, and age. Patients were assigned to 182 mg of small-intestinal release peppermint oil in enteric- coated soft gel capsules (Tempocol, WillPharma S.A.), ileocolonic release peppermint oil (Tempocol core capsules, coated with ColoPulse coating layer 12 ), or placebo. The study consisted of a two-week run-in period, an eight-week treatment period, followed by a six-month follow-up period in which no study medication was given. Patients were asked to refrain from lifestyle changes and new treatments. Standard care however, could be continued in a stable manner. Patient inclusion took place between August 2016 and March 2018. Economic evaluation The economic evaluation was performed in accordance with the Dutch guidelines for cost-calculations. 13,14 the CHEERS checklist and The Professional Society for Health Economics and Outcomes Research (ISPOR) guidelines, based on intention-to-treat analysis. Costs were calculated from the societal perspective and expressed in 2017 euros. The primary outcome of the current study is the incremental cost-effectiveness ratio (ICER), calculated as difference in costs between peppermint oil and placebo divided by the difference in QALY between peppermint oil and placebo, over the eight- week treatment period. As the newly formulated ileocolonic release peppermint oil did not yield any benefits over small-intestinal release peppermint oil 9 , this formulation will not be developed further and will not be available to patients. Consequently, this formulation was not taken into account in this economic evaluation. Costs included all IBS-related direct costs ( i.e. outpatient consultations, general practice consultation, dietician, and mental healthcare) and indirect costs ( i.e . absenteeism, presenteeism, and impaired unpaid work). Additionally, cost of treatment assigned was included (small-intestinal release peppermint oil or placebo). An overview of treatment and other costs per unit is given in Table 8.1 .