Cast versus functional brace in the rehabilitation of patients with a rupture of the Achilles tendon: statistical analysis plan for the UK study of tendo Achilles rehabilitation (UK STAR) multi-centre randomised controlled trial

Abstract Background The incidence of Achilles tendon rupture in the UK is increasing and the best rehabilitation strategy for patients treated non-operatively remains unclear. We describe a statistical analysis plan (SAP) for the UK study of tendo Achilles rehabilitation (UK STAR) multi-centre randomised trial. Methods/design UK STAR is a 1:1, multi-centre, parallel, two-arm, superiority randomised controlled trial. This study aims to evaluate the use of functional bracing compared to plaster cast for the management of acute Achilles tendon rupture in adult patients treated non-operatively. The primary outcome is the Achilles Tendon Rupture Score measured at 9 months after injury and will be estimated based on a linear mixed effects regression model adjusted for the stratification factor (centre) and other key prognostic variables. Secondary outcomes include complications, quality of life and resource use evaluated at 8 weeks and at 3, 6 and 9 months after the injury. Missing data will be summarised and reported by treatment arm. Full details of the planned analysis methods are described in this paper. Further study design details are published in the UK STAR protocol. Discussion The planned statistical analyses for UK STAR aim to reduce the risk of outcome reporting bias arising from prior data knowledge. Any changes or deviations from the current SAP will be described and justified in the final study report. Trial registration International Standard Randomised Controlled Trial Number Registry, ISRCTN62639639. Registered on 22 June 2016.