HP4: ASSESSING LIFESTYLE DRUGS FOR DRUG BENEFIT FORMULARIES: A COST-UTILITY ANALYSIS OF ORLISTAT AND SIBUTRAMINE FOR THE TREATMENT OF OBESITY IN ADULTS

Abstract

Obesity is now recognized as a chronic health condition instead of a cosmetic or lifestyle issue. Orlistat and sibutramine are effective weight-loss/weight-maintenance agents. Insurers argue that the high prevalence of obesity (i.e., body mass index (BMI)3 30kg/m2), questionable long-term health benefits, and cost of these drugs make it unfeasible to cover them. Proponents claim decreases in obesity's comorbidities would offset acquisition costs. OBJECTIVES: To provide evidence for a rational reimbursement policy for pharmacological treatments of obesity in adults. METHODS: A Markov decision analytic model was used to evaluate the cost-effectiveness of orlistat (120mg TID) and sibutramine (5–20mg QD) relative to diet and exercise alone. The model analyzed a hypothetical population of obese, but otherwise healthy 30 year olds over their lifetime. Estimates of efficacy and tolerance were derived from a meta-analysis of randomized, placebo-controlled trials of orlistat and sibutramine. The Framingham Study was used to derive risk-adjusted equations for the incidence of hypertension, dyslipidemia, and DM as well as the incidence of CV events, CV-attributable death, and non-CV death. Equations were adjusted for known risk factors, including BMI. The reference case analysis used the societal perspective and included both direct and indirect costs (discount rate, 3%). Costs were derived from the literature and inflated to year 2000 Canadian dollars (CDN$). Utilities were derived from a Canadian health survey and from the literature. Decision index: incremental cost per quality adjusted life year ($/QALY). A Monte Carlo simulation will be used to perform a sensitivity analyses around: estimated weight-loss, estimated dropout rates, estimated weight regain, cost of treatment, and major clinical events. RESULTS: Results for the base case (i.e., societal viewpoint) and third party payer (i.e., Ministry of Health) perspectives will be presented and discussed. Emphasis will be placed on the decision model approach for informing formulary decisions on “lifestyle” drugs.