The Plasma-Lyte 148 versus Saline (PLUS) statistical analysis plan: a multicentre, randomised controlled trial of the effect of intensive care fluid therapy on mortality

Background and objective: The Plasma-Lyte 148 versus Saline (PLUS) study is a prospective, multicentre, parallel-group, concealed, blinded, randomised controlled trial comparing the effect of Plasma-Lyte 148 versus 0.9% sodium chloride (saline) for fluid resuscitation and other fluid therapy on 90-day mortality among critically ill adults requiring fluid resuscitation. The original target for recruitment was 8800 participants, which was reduced to 5000 participants following the onset of the coronavirus disease 2019 (COVID-19) pandemic in 2020. This article describes the statistical analysis plan for the PLUS study. Methods: The statistical analysis plan was developed by the study statistician, chief investigator, and project manager, and was approved by the Management Committee before unblinding. The plan describes in detail the analysis of baseline characteristics, process measures, and outcomes, including covariate adjustments, subgroup analyses, missing data handling, and sensitivity analyses. Results and conclusions: A statistical analysis plan for the PLUS study was developed. This pre-specified plan accords with high quality standards of internal validity and should minimise future analysis bias.