Extended and Standard Duration Weight-Loss Program
Does a 52-week open-group weight-management program achieve greater weight loss and improvements in a range of health outcomes, and is it more cost-effective than a 12-week program?
WRAP was a nonblinded, parallel-group, randomized, controlled trial, in participants aged ≥18 years and with a body mass index (BMI) of ≥28 kg/m2 from 23 primary care practices in England. Participants were randomly assigned (2:5:5) to brief advice and self-help materials, a weight-management program (Weight Watchers) for 12 weeks, or the same weight-management program for 52 weeks and were followed up over 2 years. The primary outcome was weight at 1 year of follow-up. A within-trial incremental cost-effectiveness ratio analysis used person-level data and modeled outcomes over a 25-year time horizon using microsimulation.
A total of 1,267 eligible participants were randomly assigned to the brief intervention (n = 211), the 12-week program (n = 528), and the 52-week program (n = 528); 823 (65%) of 1,267 participants completed an assessment at 1 year, and 856 (68%) participants at 2 years. All eligible participants were included in the analyses. At 1 year, mean weight changes in the groups were –3.26 kg (brief intervention), –4.75 kg (12-week program), and –6.76 kg (52-week program). Participants in the behavioral program lost more weight than those in the brief intervention (adjusted difference, –2.71 kg; 95% confidence interval, –3.86 to –1.55). The 52-week program was more effective than the 12-week program (–2.14 kg, –3.05 to –1.22). Differences between groups were still significant at 2 years. There was improvement in fasting blood sugar and hemoglobin A1c with the 52-week program not seen in the others. Changes over time in blood pressure, quality of life, triglycerides, high-density lipoprotein, low-density lipoprotein, and total cholesterol were small and no significant differences between groups were recorded. Although the 52-week program was more expensive in the within-trial analysis, when the impact was modeled over 25 years, the 52-week program resulted in the greatest gain in quality-adjusted life-years and the greatest reduction in disease incidence.
For adults with overweight or obesity, referral to this open-group behavioral weight-loss program for at least 12 weeks is more effective than brief advice and self-help materials. A 52-week program produces greater weight loss and other clinical benefits than a 12-week program and, although it costs more, modeling suggests that the 52-week program is cost-effective in the longer-term.
The results are impressive, but for the effect on coronary risk factors. Based on randomized studies, there would have been further improvement in both weight loss and other coronary risk factors if exercise was incorporated into the programs.
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