Background: Human factors such as fatigue, circadian rhythms, scheduling, and staffing may have an impact on patient care over the course of a day across all medical specialties. Research by the transportation industry concludes that human performance is degraded by shift work, circadian rhythm disturbances, and prolonged duty. We investigated whether the timing of general surgery (specifically, increasing time of day, increasing day of week, July/August cases versus other months), and moon phase is independently related to 30-day mortality. A secondary outcome of composite in-hospital complications was also evaluated.
Methods: The binary outcomes of 32,001 elective general surgical patients at the Cleveland Clinic between January 2005 and September 2010 were analyzed according to the hour of the day (6 am to 7 pm), day of the workweek, month of the year, and moon phase in which the surgery started. Thirty-day mortality was modeled as a binary endpoint using a multivariable logistic regression, adjusting for a risk stratification index based on International Classification of Diseases (9(th) rev.) codes.
Results: The adjusted odds ratio ([Bonferroni-adjusted 95% CI]) associated with a relative increase in time of day of 4 h was 1.23 [0.91, 1.67], P = 0.09. Similarly, no association was found for day of week (0.99 [0.83, 1.17]) for a relative increase of 1 day, P = 0.85. Mortality was not significantly more frequent in July and August than in other months (adjusted odds ratio = 0.72 [0.36, 1.43], P = 0.22). Moon phase was not significantly related to mortality (P = 0.72). There were also no significant time-dependent differences in composite complications.
Conclusions: Elective general surgery appears to be comparably safe at any time of the workday, any day of the workweek, and in any month of the year.