Weekday and Survival After Cardiac Surgery-A Swedish Nationwide Cohort Study in 106 473 Patients

Background-The purpose of this study was to investigate the association between weekday of surgery and survival following cardiac surgery. Methods and Results-In a nationwide cohort study, we included all patients who underwent cardiac surgery in 1999-2013 from the SWEDEHEART (Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies) register. All-cause mortality until March 2014 was obtained from national registers. The association between weekday of surgery and mortality was estimated using Cox regression, and reported as hazard ratios with 95% CI. We used the restricted mean survival time difference to estimate loss of life related to weekday of surgery. Among 106 473 patients, 25 221 (24%), 24 471 (23%), 22 977 (22%), 20 189 (19%), 9251 (8.7%), and 4364 (4.1%) underwent surgery during a Monday, Tuesday, Wednesday, Thursday, Friday, and a Saturday/Sunday, respectively. More patients were operated on urgently during Friday to Sunday, and unadjusted analyses showed higher early and late mortality in those patients. The adjusted hazard ratios (95% CI) were 1.00 (0.89-1.13), 1.00 (0.88-1.12), 1.02 (0.90-1.16), 1.17 (1.01-1.37), and 1.05 (0.86-1.29) in patients who underwent surgery during a Tuesday, Wednesday, Thursday, Friday, and Saturday/Sunday compared to a Monday, after 1 year of follow-up conditional on 30-day survival. In elective surgery (n=46 146), the 1-year restricted mean survival time difference (95% CI) was -0.5 (-1.8-0.8), -0.5 (-1.9-0.8), -1.0 (-2.6-0.5), 0.02 (-2.2-2.3), and -1.2 (-6.3-3.9) days in patients who underwent surgery during a Tuesday, Wednesday, Thursday, Friday, and a Saturday/Sunday, respectively, compared to a Monday. Conclusions-We found no evidence of a clinically relevant weekday effect in patents who underwent cardiac surgery in Sweden during a 15-year period. These data suggest that the early risk and long-term prognosis following cardiac surgery was not affected by the weekday of surgery.