Sex-related differences in outcomes after coronary artery bypass surgery-A patient-level pooled analysis of randomized controlled trials: rationale and study protocol.

INTRODUCTION: The impact of sex on the outcomes after coronary artery bypass grafting (CABG) is controversial. The majority of CABG studies are retrospectively collected clinical or registry data, women comprise only a minority, and the reported findings represent the male predominated cohort. This individual patient meta-analysis is aimed at evaluating sex-related differences in outcomes after CABG using high quality data from randomized controlled trials (RCTs). METHODS AND ANALYSIS: A systematic literature search will be performed to identify all CABG RCTs (minimum follow-up: 5 years). Detailed specification for the minimum deidentified patient records' data requirements will be provided to RCT primary contact to request their deidentified data for pooling. The pooled analysis will follow the prospective register of systematic reviews (PROSPERO) and the preferred reporting items for systematic reviews and meta-analyses for individual patient data systematic reviews (PRISMA-IPD) recommendations and will compare sex-related outcomes after CABG. The main hypothesis is that outcomes after CABG are worse in women than in men. We will also test whether treatment effects for off-pump and the use of multiple arterial grafts are present within each sex, and also, whether there are differential treatment effects between sexes. The primary endpoint will be a composite of all-cause mortality, myocardial infarction, stroke, and repeat revascularization at long-term follow up. ETHICS AND DISSEMINATION: Ethics approval and participant consent for the study will be obtained locally by each study team if needed. Data will be disseminated and submitted to peer-reviewed scientific journals and meetings irrespective of study outcome.