Predictors of weight loss and maintenance during 2 years of treatment by sibutramine in obesity.: Results from the European multi-centre STORM trial

BACKGROUND: In this report we assess pre-treatment determinants of weight loss and maintenance outcome in The Sibutramine Trial of Obesity Reduction and Maintenance (STORM), a 2y randomized, double-blind, placebo-controlled, European multicenter study examining the effect of sibutramine (Sib) on inducing and maintaining weight loss in obese subjects. MATERIAL: A total of 605 obese patients (BMI: 30-45 kg/m(2)) of both gender were included from eight European centers and treated for 24 months. The patients were treated for the initial 6 months by Sib (10 mg/day) and a low-fat low-energy, individualized diet (600 kcal/day deficit). The 467 patients who achieved > 5% weight loss after 6 months were randomized 3:1 to Sib (10 mg/day) (Sib/Sib) and placebo (Sib/Pla) for weight maintenance over a further 18 months. MAIN OUTCOME AND ANALYSES: Pre-treatment individual characteristics were assessed as predictors of 6 months weight loss (kg) and 24 months weight maintenance using simple and multivariate correlation and regression analyses. RESULTS: In univariate analyses, the 6 month weight loss (n = 505) was positively associated with pre-treatment body weight (r = 0.27), height (r = 0.18), fat-free mass (r = 0.21) (all P < 0.001), fat mass (r= 0.1 3, P < 0.03), and resting metabolic rate (r= 0.1 3, P < 0.003). However, no relation was found with age, gender, smoking status, age at onset of obesity, or number of previous slimming attempts. The same predictors were found for weight change to endpoint in the Sib/Sib group (n = 350), while no predictors were identified in the Sib/Pla (n = 114). In the multivariate regression analysis only pre-treatment body weight predicted weight loss at 6 months (P < 0.001). Weight change (kg) to 24 month was predicted by: 4.34 + 0.07*body weight (kg) 4*treatment (Sib = 1, Pla = 0) - 0.06*age (y), (r(2) = 8%, P < 0.001). CONCLUSION: Only pre-treatment body weight seems to be an important independent predictor of 6 months weight loss and 24 month weight maintenance in this study on diet and Sib. As only 8% of the variation in 24 months weight change could be explained by the predictors, the clinical value of this information is limited.