Weekend versus weekday cardiac surgery: A comprehensive meta-analysis of more than 500,000 cases with meta-regression

Objectives The "weekend effect" describes worse outcomes with weekend hospital care, but its impact on cardiac surgery remains unclear. We performed a comprehensive meta-analysis and meta-regression to assess whether weekend cardiac surgery is associated with poorer perioperative outcomes than weekday procedures. Methods PubMed, Scopus, and the Cochrane Library were systematically searched for studies comparing weekend versus weekday cardiac surgery outcomes. Pooled odds ratios (ORs) and mean differences with 95% CIs were calculated using a random-effects model. Subgroup analyses were performed by procedure type (emergent, coronary artery bypass grafting, acute type A aortic dissection) and geographic region. Meta-regressions explored effects of mean age, percentage of female patients, proportion of emergent cases, and publication year. A day-by-day mortality heat map was constructed to assess daily trends. Results Seventeen studies comprising 527,195 patients were included; 7.4% underwent surgery on weekends. Weekend surgery was associated with significantly greater mortality (OR, 1.5; 95% CI, 1.2-1.8; P = .001) and longer stay in the intensive care unit (mean difference, 0.4 days; 95% CI, 0.1-0.7; P = .01). No significant differences were found for acute kidney injury, stroke, aortic crossclamp time, reoperation for bleeding, or total hospital stay. The incidence of transient ischemic attack was slightly lower on weekends (OR, 0.8; 95% CI, 0.6-1.0; P = .02). Subgroup analyses showed consistently elevated mortality in weekend cases across emergent, coronary artery bypass grafting, and acute type A aortic dissection subgroups, and in studies from Asia and the United States but not Europe. Meta-regression showed no significant effect of age, sex, emergent case proportion, or publication year on mortality differences. Conclusions Weekend cardiac surgery is associated with greater mortality and longer stay in the intensive care unit, independent of case mix. The absence of patient-level effect modification suggests that systemic or institutional factors, rather than patient acuity, underlie the weekend effect, supporting the need for policies ensuring consistent care across all days.