Background: Because surgical residents' level of experience may be at its nadir early in the academic year, academic seasonality-or the "July effect"-could affect cardiac surgical outcomes.
Methods: Prospectively collected data from the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program were used to identify 70,616 consecutive cardiac surgical procedures performed between October 1997 and October 2007. Morbidity and mortality rates were compared between early (July 1 to August 31, n = 11,975) and late (September 1 to June 30, n = 58,641) periods in the academic year. A prediction model was constructed by using stepwise logistic regression modeling.
Results: The two patient groups had similar demographic and risk variables. Isolated coronary artery bypass grafting accounted for 76.7% of early-period procedures and 75.8% of later-period procedures (p = 0.03). Morbidity rates did not differ significantly between the early (14.0%) and later periods (14.2%; odds ratio [OR], 1.01; 95% confidence interval [CI], 0.96 to 1.07; p = 0.67) and operative mortality was similar, 3.7% vs 3.9% (OR, 0.99; 95% CI, 0.89 to 1.11; p = 0.90). The early portion of the year was associated with longer cardiac ischemia times (84 +/- 40 vs 83 +/- 42 minutes), cardiopulmonary bypass times (126 +/-52 vs 124 +/-56 minutes), and total surgical times (295 +/- 90 vs 288 +/- 90 minutes; p < 0.05 for all).
Conclusions: The early part of the academic year was associated with slightly longer operative times; however, risk-adjusted outcomes were similar in both periods. This finding should lessen concerns about the quality of cardiac surgical care at the beginning of the academic year.