OBJECTIVE: To assess the effectiveness of evidence-based treatment of obesity in a primary care setting, we conducted the S.A.T.-trial (Sibutramine in Adiposity Trial) which is a multicenter, double-blind, placebo-controlled, randomized parallel group comparison of 54-week continuous therapy with Sibutramine 15 mg or Placebo in addition to a standardized non-pharmacological therapy consisting of a calorie-restricted diet, modification of eating behavior and lifestyle, and an activity programme. Patients with a BMI between 30 and 40 are included. The primary endpoint in this study is weight loss in kg between the last measurement of body weight (visit 11) and the measurement at the first visit. Secondary endpoints are amongst other clinical parameters health economic and quality of life data. Since the random code is still not broken, the results given in this abstract refer to all randomized obese patients in the study (both Sibutramine and placebo group). The presentation in November will show the results for the two patient groups separately. QUALITY OF LIFE MEASURES: Quality of life is measured by 4 different instruments: the Short Form 36 (SF-36): the EuroQol, the Time-trade-off-Method (TTO) and the Willingness-to-pay-Method (WTP). The SF-36 is a general, standardized and validated Quality-of-life-instrument, consisting of 36 questions that can be aggregated into 8 health dimensions. The EuroQol is also a general, standardized and validated quality-of-life-questionnaire, having the advantage of aggregating the five health dimensions into one quality-of-life-index. Therefore, the EuroQol is frequently used in health economic evaluations to calculate Quality adjusted life years saved (QALYs). In the TTO interview patients are asked questions to calculate a quality-of-life-index for each patient stratified by age. In the willingness-to-pay-questionnaire, obese patients are asked how much they would be prepared to pay per month for an immediate and sustained weight loss of 10 kg from their current body weight. The answers are stratified by net income classes. RESULTS: Quality of life measured by the SF 36 has improved in all 8 health dimensions at visit 2 compared to visit 1. Especially energy/fatigue is impaired in obese patients. The quality-of-life-index measured by the EuroQol has slightly improved from visit 1 to visit 2 over all age-groups. The quality-of-life-index of the TTO-interview and the EuroQol-questionnaire are very similar except for the age group <35 years. Willingness-to-pay correlates positively with net income. DISCUSSION: The results are preliminary, but in line with the published literature. They reveal the massive burden of obese patients.