2125. Cardiovascular Daytime Varying Effect on Surgical Site Infections and 1-Year Mortality in Cardiac Surgery

BACKGROUND: Certain cardiovascular diseases show diurnal variation, with a higher incidence of myocardial infarction in the morning. Conversely, aortic valve replacement surgery performed in the afternoon provided less myocardial injury and improved patient outcomes. We therefore examined a potential daytime varying effect on surgical site infection (SSI) and 1-year mortality in cardiac surgery. METHODS: Data from the prospective, validated Swiss national SSI surveillance system with a post-discharge follow-up rate >90% from adult patients undergoing cardiac surgery in 16 hospitals were analyzed from 2009 to 2014. Patients operated during nighttime and/or as emergency were excluded. The main exposure was time (morning/afternoon) of surgery. The primary outcome was SSI incidence, defined according to CDC criteria; a secondary outcome was 1-year mortality. We fitted generalized linear and additive models (GAM) to describe daytime varying effects predicting the outcome parameters and adjust for confounding variables. RESULTS: Of the 16,841 surgeries included, 11,850 (70%) started between 7 a.m. and 12 a.m. while the remaining 4,991 (30%) started between 12 a.m. and 4 p.m. Baseline characteristics of morning vs. afternoon surgeries are shown in Figure 1. The overall SSI (including graft excision sites) and 1-year mortality rates were 5.9 and 4.7%, respectively. After adjustment for confounders, afternoon surgery was not associated with lower SSI (OR 1.0, 95% CI 0.99–1.0, P = 0.42), or 1-year mortality rate (OR 1.0, 95% CI 1.0–1.01, P = 0.24) than morning surgery. A GAM did not detect a relevant daytime-varying effect on SSI (P = 0.36, Figure 2), but an increase in 1-year mortality in function of daytime (P = 0.02, Figure 3). An adjusted subgroup analysis confirmed increased mortality for incision between 9 a.m. and 4 p.m. compared with 7–9 a.m. (OR 1.01, 95% CI 1–1.02, P = 0.003). CONCLUSION: This large study did not find a decreased SSI and/or mortality rate for afternoon surgeries. Therefore, the previous findings of reduced myocardial injury due to afternoon surgery cannot be generalized to these important clinical outcome parameters. DISCLOSURES: All authors: No reported disclosures.