A cluster RCT and process evaluation evaluating the effectiveness of an optimisation intervention to promote parental engagement in a childhood obesity prevention programme: Results of the Optimising Family Engagement in HENRY (OFTEN) trial

Background Low parental participation reduces the impact and sustainability of public health childhood obesity prevention programmes. Using data from a focused ethnography, we developed a multi-level, theory-based implementation optimisation intervention. The optimisation intervention aimed to support local authorities and children’s centres to adopt behaviours to promote engagement in ‘HENRY (Health Exercise Nutrition for the Really Young)’, a UK community obesity prevention intervention. Methods We evaluated the effectiveness of the optimisation intervention on programme enrolment and completion over a 12 implementation period in a cluster randomised controlled trial. We randomised 20 local government authorities (with 126 children’s centres) to HENRY plus the optimisation intervention or to HENRY alone. Primary outcomes were (1) the proportion of centres enrolling at least eight parents per programme and (2) the proportion of centres with a minimum of 75% of parents attending at least five of eight sessions per programme. Trial analyses adjusted for stratification factors (pre-randomisation implementation of HENRY, local authority size, deprivation) and allowed for cluster design. A parallel mixed-methods process evaluation used qualitative interview data and routine monitoring to explain trial results. Results Neither primary outcome differed significantly between groups; 17.8% of intervention centres and 18.0% of control centres achieved the parent enrolment target (adjusted difference -1.2%; 95%CI: -19.5%, 17.1%); 17.1% of intervention centres and 13.9% of control centres achieved the attendance target (adjusted difference 1.2%; 95%CI: -15.7%, 18.1%). Unexpectedly, the trial coincided with substantial national service restructuring, including centre closures and reduced funds. Some commissioning and management teams stopped or reduced implementation of both HENRY and the optimisation intervention due to competing demands. Thus, at follow up, HENRY programmes were delivered to approximately half the number of parents compared to baseline (n=433 vs. 881). Conclusions During a period in which services were reduced by policies outside the realm of this research, this first definitive trial found no evidence of effectiveness for an implementation optimisation intervention promoting parent engagement in an obesity prevention intervention. Trial registration: ClinicalTrials.gov Identifier: NCT02675699 registered 4th February 2016. https://clinicaltrials.gov/ct2/show/NCT02675699