Zsa Zsa Weerts

Cost-effectiveness of peppermint oil in IBS 197 8 groups in indirect costs during the treatment period, except for a higher productivity loss in unpaid work in the small-intestinal peppermint oil group ( Table 8.3 ). Table 8.3 Total costs per category (ITT-population). Placebo Small-intestinal release Peppermint oil Difference in means ♮ (€) (95% CI) N =64 N =62 Costs , mean (SD) (€) Total direct costs Mental healthcare General practice Rehabilitation Outpatient consultation Company doctor Homeopathy Medication Dietician Travelling-expenses Treatment or diagnostics Hospitalization Study treatment costs Total indirect costs Absenteeism Presenteeism Productivity loss unpaid work 355 (90) 287 (90) 29 (2) 0 (0) 3 (1) 7 (2) 7 (2) 2 (0) 1 (0) 2 (0) 17 (6) - N.A. 818 (73) 386 (59) 364 (20) 68 (10) 161 (11) 69 (8) 19 (2) 0 (0) 4 (1) 8 (2) 8 (3) 1 (0) 5 (1) 1 (0) 6 (2) - 42 (0) 975 (78) 453 (71) 371 (21) 145 (19) -194 (-392;-35)* -218 (-411;-57)* -11 (-17;-5)* 0 (0) 0 (-2; 3) 0 (-5; 6) 0 (-6; 7) -1 (-2;0) 4 (2;5)* -1 (-2;0) -11 (-24;0) - - 157 (-55;370) 71 (-103;256) 7 (-50;65) 77 (37;120)* Total costs , mean (SD) 1.175 (113) 1.132 (82) -40 (-226;322) ♮ Bootstrapped differences (means and confidence intervals) between small-intestinal release peppermint oil and placebo. CI Confidence Interval. * significant (no zero in confidence interval). Cost-effectiveness analysis The incremental cost-savings of small-intestinal peppermint oil were €40.00, with an incremental corrected QALY gain over eight-weeks of 0.004 compared to placebo. The cost-effectiveness plane is presented in Figure 8.1 and shows that small-intestinal release peppermint oil is a dominant treatment compared to placebo in 46% of simulations (southeast quadrant, greater effectiveness at lower costs). Peppermint oil is more effective, but at a higher cost (northeast quadrant) in 31% of the simulated ratios, while it is inferior in 18% of simulations (northwest quadrant, less effective and higher costs). The net benefit acceptability curve showed that the probability of peppermint oil being cost-effective was 50% at a WTP-threshold of €1.000 and increased to 56% at a WTP threshold of €10.000 ( Figure 8.2 ).