Validation of 'Days Alive and out of Hospital' as an Outcome Measure After Coronary Artery Bypass Graft Surgery, Acute Coronary Syndrome and Heart Failure Hospitalisation.

Background and Rationale Days alive and out of hospital (DAOH) is a composite outcome measure that integrates several outcomes, including death, hospital length-of-stay, and hospital readmission. The minimum clinical important difference (MCID) in DAOH and its relation to clinically important long-term outcomes has not yet been studied for patients admitted to hospital for coronary artery bypass graft surgery (CABG), acute coronary syndrome (ACS), or heart failure (HF). We propose to determine whether differences in DAOH in common use as a MCID in clinical trials will be associated with significant differences in clinically important outcomes. Methods and AnalysisThis is a retrospective observational cohort study in three separate cohorts of adult ([≥]18 years) patients admitted to National Health Service (NHS) hospitals in England for: i) ACS ii) CABG iii) HF. Patients will be identified through Hospital Episode Statistics (HES) Admitted Patient Care (APC) data from 01/01/2009 - 31/12/2015 and followed up to 5 years after the index admission date. Adjusted and unadjusted multivariable fractional polynomial Cox regression models will be used to estimate HRs for primary outcomes, according to pre-specified differences in DAOH. Ethics and DisseminationThis is a sub study of the observational cohort study In Silico Trials of Surgical Interventions - Using Routinely Collected Data to Model Trial Feasibility and Design Efficiency In Vivo Randomised Controlled Trials - ClinicalTrials.gov Identifier: NCT05853536. Ethical approval has been obtained from University of Leicester Research Ethics Committee (22322-yll15-ls:cardiovascularsciences). Findings from this study will be disseminated through peer-reviewed scientific publications and research conferences.