Childhood obesity prevention trials: A systematic review and meta-analysis on trial design and the impact of type 1 error

Effect sizes from previously reported trials are often used to determine the meaningful change in weight in childhood obesity prevention interventions because information on clinically meaningful differences is lacking. Estimates from previous trials may be influenced by statistical significance; therefore, it is important that they have a low risk of type 1 error. A systematic review and meta-analysis were conducted to report on the design of child obesity prevention randomized controlled trials and effectiveness according to risk of type 1 error. Eighty-four randomized controlled trials were identified. A large range of assumptions were applied in the sample size calculations. The most common primary outcome was BMI, with detectable effect size differences used in sample size calculations ranging from 0.25 kg/m2 (followed up at 2 years) to 1.1 kg/m2 (at 9 months) and BMI z-score ranging from 0.1 (at 4 years) to 0.67 (at 3 years). There was no consistent relationship between low risk of type 1 error and reports of higher or lower effectiveness. Further clarity of the size of a meaningful difference in weight in childhood obesity prevention trials is required to support evaluation design and decision-making for intervention and policy. Type 1 error risk does not appear to impact effect sizes in a consistent direction.</p

Contamination within trials of community-based public health interventions: lessons from the HENRY feasibility study

Introduction: Contamination occurs when participants allocated to trial control arms receive elements of the active intervention. Randomisation at cluster level, rather than individual level, may reduce or eliminate contamination, avoiding the dilution of intervention effectiveness that it may cause. However, cluster randomisation can result in selection bias and may not be feasible to deliver. We explored the extent of contamination in a qualitative study nested within a feasibility study of HENRY (Health, Exercise and Nutrition for the Really Young); a UK community-based child obesity prevention programme. We aimed to determine the nature and impact of contamination to inform a larger planned trial and other trials in community based public health settings. Method: We invited participants to take part in the nested qualitative study who were already involved in the HENRY feasibility study. Semi-structured interviews/focus groups were conducted with children’s centre managers (n=7), children’s centre staff (n=15), and parents (n=29). Data were transcribed and analysed using an integrative approach. First, deductively organised using a framework guided by the topic guide and then organised using inductive thematic analysis. Results: Potential for contamination between treatment arms was recognised by all stakeholder groups. Staff within the intervention centres presented the greatest risk of contamination, predominantly because they were often asked to work in other children centre’s (including control group centres). ‘Sharing of best practice’ by staff was reported to be a common and desirable phenomenon within community based settings. Parental sharing of HENRY messages was reported inconsistently; though some parents indicated a high degree of knowledge transfer within their immediate circles. Conclusions: The extent of contamination identified has influenced the design of a future effectiveness trial of HENRY which will be clustered at the centre level (with geographically distinct clusters). The common practice of knowledge sharing amongst community teams means that this clustering approach is also likely to be most suitable for other trials based within these settings. We provide recommendations (e.g. cluster randomisation, training intervention facilitators on implications of contamination) to help reduce the impact of contamination in public health intervention trials with or without clustering, whilst enabling transfer of knowledge where appropriate. Trial registration: ClinicalTrials.gov Identifier NCT03333733 registered 6th November 2017

Cluster randomised controlled feasibility study of HENRY: a community-based intervention aimed at reducing obesity rates in preschool children

BackgroundCommunity-based obesity prevention interventions are often commissioned despite the limited evidence base. HENRY (Health, Exercise, Nutrition for the Really Young) is a programme delivered to parents of preschool children across the UK. Early evidence suggests that it may be effective, but a robust evaluation has not been conducted. We initiated a systematic evaluation of HENRY by studying the feasibility of conducting a multi-centre definitive trial to evaluate its effectiveness and cost-effectiveness to prevent obesity. Objectives were to assess the feasibility of recruiting local authorities, centres and parents; test processes and time required to train and certify intervention staff; explore HENRY commissioning processes; identify potential sources (and associated impact) of contamination; and consider the feasibility of trial procedures.MethodsWe conducted a multi-centre, open labelled, two group, prospective, cluster randomised, controlled, feasibility study, with embedded process evaluation and pre-defined criteria for progression to definitive trial. We sought to recruit 120 parents from 12 children’s centres, across two UK local authority (government) areas. Within each local authority, we planned to randomise three centres to HENRY and three to ‘standard care’ control. Our plan was to collect data in family homes at baseline and 12 months, including parent and child height and weight, and parent-reported questionnaires on self-efficacy, feeding, eating habits, quality of life and resource use. Contamination, implementation and study acceptability were explored using parent interviews.ResultsWe recruited two local authorities and 12 children’s centres within eight months. One hundred and seventeen parents were recruited (average 3.9 parents per programme) and follow-up data were collected from 85% of participants. Process data from 20 parents and 24 members of staff indicate that both would benefit from more detail about their involvement as participants, but that methods were acceptable. Contamination was likely, though the impact of this on behaviour was unclear.ConclusionOur findings indicate that a cluster RCT of HENRY to assess its effect on childhood obesity prevention is feasible. This study has allowed us to design a pragmatic definitive trial with minimal bias, taking account of lessons learnt from conducting evaluation research in public health settings.Trial registrationClinicalTrials.gov Identifier NCT03333733 registered 6th November 2017.</div

Contamination: friend or foe? The extent and implication of contamination within RCT’s of community-based child obesity prevention interventions

Conference abstract

Collection of cancer Patient Reported Outcome Measures (PROMS) to link with primary and secondary electronic care records to understand and improve long term cancer outcomes: A protocol paper

Introduction More people are living with and beyond a cancer diagnosis. There is limited understanding of the long-term effects of cancer and cancer treatment on quality of life and personal and household finances when compared to people without cancer. In a separate protocol we have proposed to link de-identified data from electronic primary care and hospital records for a large population of cancer survivors and matched controls. In this current protocol, we propose the linkage of Patient Reported Outcomes Measures data to the above data for a subset of this population. The aim of this study is to investigate the full impact of living with and beyond a cancer diagnosis compared to age and gender matched controls. A secondary aim is to test the feasibility of the collection of Patient Reported Outcomes Measures (PROMS) data and the linkage procedures of the PROMs data to electronic health records data. Materials and methods This is a cross-sectional study, aiming to recruit participants treated at the Leeds Teaching Hospitals National Health Service Trust. Eligible patients will be cancer survivors at around 5 years post-diagnosis (breast, colorectal and ovarian cancer) and non-cancer patient matched controls attending dermatology out-patient clinics. They will be identified by running a query on the Leeds Teaching Hospitals Trust patient records system. Approximately 6000 patients (2000 cases and 4000 controls) will be invited to participate via post. Participants will be invited to complete PROMs assessing factors such as quality of life and finances, which can be completed on paper or online (surveys includes established instruments, and bespoke instruments (demographics, financial costs). This PROMs data will then be linked to routinely collected de-identified data from patient’s electronic primary care and hospital records. Discussion This innovative work aims to create a truly ‘comprehensive patient record’ to provide a broad picture of what happens to cancer patients across their cancer pathway, and the long-term impact of cancer treatment. Comparisons can be made between the cases and controls, to identify the aspects of life that has had the greatest impact following a cancer diagnosis. The feasibility of linking PROMs data to electronic health records can also be assessed. This work can inform future support offered to people living with and beyond a cancer diagnosis, clinical practice, and future research methodologies