Sensitivity analysis
Sensitivity analysis demonstrated an incremental cost per QALY of euro11 000–35 000 under a variety of assumptions (Table 4). Using 1-y data from the XENDOS study in the model, we estimated a cost per QALY of euro14 950. This was lower than the base-case because of a higher QALY gain for orlistat. The most critical assumptions were duration of sustained effect and daily dose. For example, the lowest cost per QALY arose when it was assumed that patients took only 2.1 tablets per day. This resulted in lower drug costs. The highest cost per QALY arose when it was assumed that all weight was regained within the first year post treatment as the QALYs gained were lower with orlistat.