Statistical analysis plan for the Healthy Hands Project; single centre cluster-randomised clinical trial of a skin care program for the prevention of contact dermatitis in health care workers

Background: The Healthy Hands Project (HHP) is a randomised clinical trial aiming to determine the effectiveness of an intervention program in the prevention of hand dermatitis in healthcare workers (HCWs). The intervention is comprised of placing dispensers with hand creams on wards combined with continuous electronic monitoring of cream consumption and regular feedback to HCWs. The clinical severity (HECSI score) was used as the primary outcome and natural moisturising factor (NMF) levels as the secondary outcome. The study protocol for the cluster-randomised controlled trial of HHP was published in Trials in 2017. This article describes the detailed statistical analysis plan for the HHP trial. Methods/design: The HHP is a single-centre, cluster-randomised controlled trial with two parallel groups and blinded outcome assessment. This update article presents (1) the descriptive statistics of the primary and secondary outcomes, (2) the statistical models used for the analysis of the main outcomes, (3) sensitivity analyses on the effect of observed exposure to wet work, (4) handling of missing data including sensitivity analysis and (5) an updated power calculation. This statistical analysis plan was written prior to unblinding of the study. Discussion: This paper presents a comprehensive statistical analysis plan for the data resulting from the HHP trial. It supports transparency in reporting by clarifying differences between the previously published protocol and the proposed actual statistical analyses. Trial registration: Netherlands Trial Register (NTR), identification number NTR5564. Registered on 2 November 2015.