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 l oss and maintenance outcome in The Sibutramine Trial of Obesity Reduction a nd Maintenance (STORM), a 2y randomized, double-blind, placebo-controlled, European multicenter study examining the effect of sibutramine (Sib) on ind ucing 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 p atients 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 patient s 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 fu rther 18 months. MAIN OUTCOME AND ANALYSES: Pre-treatment individual characteristics were as sessed as predictors of 6 months weight loss (kg) and 24 months weight main tenance using simple and multivariate correlation and regression analyses. RESULTS: In univariate analyses, the 6 month weight loss (n = 505) was posi tively 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 w as found with age, gender, smoking status, age at onset of obesity, or numb er of previous slimming attempts. The same predictors were found for weight change to endpoint in the Sib/Sib group (n = 350), while no predictors wer e identified in the Sib/Pla (n = 114). In the multivariate regression analy sis 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 we ight (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 indepen dent predictor of 6 months weight loss and 24 month weight maintenance in t his 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 inf ormation is limited.