The Active for Life Year 5 (AFLY5) school-based cluster randomised controlled trial protocol: detailed statistical analysis plan

BACKGROUND The Active For Life Year 5 (AFLY5) randomised controlled trial protocol was published in this journal in 2011. It provided a summary analysis plan. This publication is an update of that protocol and provides a detailed analysis plan. UPDATE This update provides a detailed analysis plan of the effectiveness and cost-effectiveness of the AFLY5 intervention. The plan includes details of how variables will be quality control checked and the criteria used to define derived variables. Details of four key analyses are provided: (a) effectiveness analysis 1 (the effect of the AFLY5 intervention on primary and secondary outcomes at the end of the school year in which the intervention is delivered); (b) mediation analyses (secondary analyses examining the extent to which any effects of the intervention are mediated via self-efficacy, parental support and knowledge, through which the intervention is theoretically believed to act); (c) effectiveness analysis 2 (the effect of the AFLY5 intervention on primary and secondary outcomes 12 months after the end of the intervention) and (d) cost effectiveness analysis (the cost-effectiveness of the AFLY5 intervention). The details include how the intention to treat and per-protocol analyses were defined and planned sensitivity analyses for dealing with missing data. A set of dummy tables are provided in Additional file 1. DISCUSSION This detailed analysis plan was written prior to any analyst having access to any data and was approved by the AFLY5 Trial Steering Committee. Its publication will ensure that analyses are in accordance with an a priori plan related to the trial objectives and not driven by knowledge of the data. TRIAL REGISTRATION ISRCTN50133740.