Evaluating the impact of Weight-loss Referrals for Adults in Primary care (WRAP): a pragmatic randomised controlled trial.
There is good evidence that primary care referral to open group commercial weight loss programmes (CP) is an effective treatment for obesity, but there is debate about the optimal duration of intervention.
This non-blinded randomised controlled parallel group trial recruited participants (32% men, age≥18 years, BMI≥28 kg/m²) through 23 primary care practices in England. More than half of participating practices were from areas with an index of multiple deprivation higher than the national median. Participants were randomised in a 2:5:5 allocation to: brief self-help intervention (BI), referral to a CP for 12 weeks (CP12), referral to the same CP for 52 weeks (CP52). The primary outcome was weight at 12 months, analysed using mixed effects models under the assumption of missing at random in a hierarchical closed testing procedure comparing combined CP arms v BI, and then CP52 v CP12. Potential interactions were examined between intervention effects and gender, educational qualification and income.
Between October 2012 and February 2014, 1269 participants were enrolled (211 BI; 530 CP12; 528 CP52). 823 (65%) completed the 12 month visit (124 BI, 339 CP12, 360 CP52). Mean weight change at 12 months was -3·40 kg in BI, -4·99 kg in CP12, and -7·03 kg in CP52. Participants in the CP arms lost more weight than BI participants [adjusted difference = -2·79 kg (95% CI -4·10,-1·47); p<0·0001] and CP52 participants lost more weight than CP12 participants [adjusted difference= -2·32 kg (95% CI -3·38, -1·26); p<0·0001]. There was no evidence that the intervention effect differed by gender (p=0.48), educational attainment (p=0.79), or household income (p=0.64) of the participants. Participants reported no related adverse events.
Referral to a CP for at least 12 weeks leads to greater weight loss than brief intervention and is an effective intervention for a broad cross-section of the population seen in routine primary care settings. Longer duration (52 weeks) of referral resulted in greater weight loss than shorter (12 week) referral. Greater efforts are needed to encourage people who would benefit most from such referral programmes to attend in order to reduce health inequalities.