Primary care referral to a commercial provider for weight loss treatment versus standard care: a randomised controlled trial

Methods In this parallel group, non-blinded, randomised controlled trial, 772 overweight and obese adults were recruited by primary care practices in Australia, G ermany, and the UK. Participants were randomly assigned with a computer-generated simple randomisation sequence to receive either 12 months of standard care as defi ned by national treatment guidelines, or 12 months of free membership to a commercial programme (Weight Watchers), and followed up for 12 months. The primary outcome was weight change over 12 months. Analysis was by intention to treat (last observation carried forward [LOCF] and baseline observation carried forward [BOCF]) and in the population who completed the 12-month assessment. This trial is registered, number ISRCTN85485463. Findings 377 participants were assigned to the commercial programme, of whom 230 (61%) completed the 12-month assessment; and 395 were assigned to standard care, of whom 214 (54%) completed the 12-month assessment. In all analyses, participants in the commercial programme group lost twice as much weight as did those in the standard care group. Mean weight change at 12 months was –5∙06 kg (SE 0·31) for those in the commercial programme versus –2∙25 kg (0·21) for those receiving standard care (adjusted diff erence –2∙77 kg, 95% CI –3∙50 to –2∙03) with LOCF; –4∙06 kg (0·31) versus –1∙77 kg (0·19; adjusted diff erence –2∙29 kg, –2∙99 to –1∙58) with BOCF; and –6∙65 kg (0·43) versus –3∙26 kg (0·33; adjusted diff erence –3∙16 kg, –4∙23 to –2∙11) for those who completed the 12-month assessment. Participants reported no adverse events related to trial participation.