Base-case
After 12 months, patients receiving orlistat had lost 11.6% in weight compared with 7.9% in those receiving placebo. Orlistat responders lost 15.5% of their initial weight. In addition, the criterion of a response (ie ≥5% loss in weight) at 3 months was met by twice as many patients in the group treated with orlistat plus a calorie-reduced diet (49%) as in the group who only received a calorie-reduced diet (26%). No correction was made for those who dropped out during the 3–12-month period as the % dropouts for orlistat and placebo were similar.
As a result of weight loss in the 52-week period, the model predicted that orlistat responder patients had a 0.14-y shorter period of time with diabetes over the 11-y modelling period, than those who had not lost weight (Table 3). Placebo-treated patients had a 0.07-y shorter period of time with diabetes. For orlistat-responders this was associated with a saving of euro353 in diabetes-related costs over the same period. This should be compared with savings of euro119 and euro179 for orlistat nonresponders and placebo (diet alone) (Table 3). The incremental cost for the average orlistat-treated patient was euro478. The net utility gain in the orlistat arm was 0.028 compared with placebo but the orlistat responders gained 0.090 compared to placebo patients as a result of 1 year's orlistat treatment (Table 3). The number needed to treat (NNT) to achieve a gain of one QALY was 35. The incremental cost per QALY gained was euro16 954.