Overview
Health-care costs and benefits (ie quality-adjusted-life-years (QALYs) gained) were estimated by comparing orlistat in combination with a 12-month dietary programme with a dietary programme alone in the treatment of obese patients without diabetes. In line with National Institute of Clinical Excellence (NICE) guidance on orlistat22 and summary of product characteristics (SPC), we assumed that after 3 months of treatment with orlistat, only treatment responders (ie those who achieve at least 5% reduction in body weight) continue treatment with orlistat. Our model used data on weight loss at 12 months with orlistat in combination with a dietary programme from five randomized, placebo-controlled trials. The model also incorporated known relationships between weight loss and quality of life (utility) gain, and weight loss and reduction in risk of T2DM to predict the impact of weight loss on QALYs gained and on reduced time with T2DM. The costs associated with each treatment arm included the acquisition cost of orlistat, cost of a calorie-controlled dietary programme and monitoring and treatment costs associated with T2DM. The difference in total costs between the treatment arms were compared with the difference in QALYs gained to estimate the incremental cost per QALY for orlistat. All costs were evaluated from the perspective of the Irish health-care system. The model was run for an 11-y period (treatment year plus 10 y post treatment) to capture treatment effects on diabetes incidence and associated costs.
The treatment algorithm is summarized in Figure 1. Key demographic and weight loss data used in the model are summarized in Table 1.