Comorbidity-modified biomarker prediction of postoperative atrial fibrillation after cardiac surgery: a scoping review

Abstract

Postoperative atrial fibrillation (POAF) complicates 20–50% of cardiac surgical procedures and is associated with increased stroke risk, prolonged hospitalisation, and mortality. Numerous circulating and clinical biomarkers have been proposed for POAF risk stratification; however, diabetes, chronic kidney disease (CKD), and obesity are typically entered as adjustment covariates rather than assessed as effect modifiers of biomarker performance. This scoping review mapped the extent to which the POAF biomarker literature evaluates comorbidities as modifiers of predictive performance. Following the Arksey and O’Malley framework and PRISMA-ScR reporting guidance, PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception, without date or language restriction, alongside backward and forward citation chasing of the included sources. Two reviewers independently screened the records and extracted the data; disagreements were resolved by discussion or by a third reviewer. Data were descriptively synthesised. Out of 1,409 records identified, 887 remained after de-duplication, and 845 were excluded at title/abstract screening, leaving 42 reports for full-text retrieval (one could not be retrieved). Of the 41 reports assessed in full text, 23 studies met the inclusion criteria, and 18 were excluded for documented reasons. Diabetes was the most frequently assessed comorbidity, reported in 21 of 23 studies, almost always as an adjustment covariate or unstratified baseline characteristic rather than a formally tested interaction term. Only two studies performed explicit statistical interaction testing between comorbidities and candidate predictors for POAF, and both found no significant interactions. Chronic kidney disease and obesity were assessed less frequently and with limited methodological rigor. Comorbidities are rarely evaluated as genuine effect modifiers of biomarker performance in POAF prediction research. Although diabetes has been formally tested, it does not appear to modify predictor performance, although the evidence base is too sparse to draw firm conclusions. Future POAF biomarker studies should pre-specify and report comorbidity-stratified or interaction analyses to clarify whether comorbidity-tailored risk models are warranted.