The iHealth-T2D study: Statistical analysis plan for a cluster randomised controlled trial with intensive family-based lifestyle modification programme to reduce type 2 diabetes risk amongst South Asians

Abstract

AbstractBackgroundSouth Asians are at high risk of type 2 diabetes (T2D). Lifestyle modification is effective at preventing T2D amongst South Asians, but the approaches to screening and intervention are limited by high-costs, poor scalability and thus low impact on T2D burden. An intensive family-based lifestyle modification programme for prevention of T2D was developed. The aim of the iHealth-T2D trial is to compare the effectiveness of this programme with usual care.MethodsThe iHealth-T2D trial is designed as a cluster randomised controlled trial (RCT) conducted at 120 locations across India, Pakistan, Sri Lanka and the UK. A total of 3,682 South Asian men and women with age between 40-70 years without T2D but at elevated risk for T2D [defined by central obesity (waist circumference ≥95cm in Sri Lanka, or ≥100cm in India, Pakistan and UK) and/or prediabetes (HbA1c ≥6.0%)] were included in the trial. Here we describe in detail the statistical analysis plan (SAP), which was finalised before outcomes were available to the investigators. The primary outcome will be evaluated after three years of follow-up after enrolment to the study, and is defined as T2D incidence in the intervention arm compared to usual care. Secondary outcomes are evaluated both after one and three years of follow-up and include biochemical measurements, anthropometric measurements, behavioural components and treatment compliance.DiscussionThe iHealth-T2D trial will provide evidence whether an intensive family-based lifestyle modification programme in South Asians who are at high risk for T2D is effective in the prevention of T2D. The data from the trial will be analysed according to this pre-specified SAP.Ethics and disseminationThe trial was approved by the international review board of each participating study site. Study findings will be disseminated through peer-reviewed publications and in conference presentations.Trial registrationEudraCT 2016-001350-18. Registered 14 April 2016 https://www.hra.nhs.uk/planning-and-improving-research/application-summaries/research-summaries/ihealth-t2d/; ClinicalTrials.govNCT02949739. Registered 31 October 2016, https://clinicaltrials.gov/ct2/show/NCT02949739, First posted 31/10/2016.