Methods: We identified all patients captured in the Truven Health Analytics MarketScan® Hospital Drug Database who had CABG performed between 2007-2010. Patients who had ICD-9-CM codes indicating mediastinitis (519.2) or sternectomy/muscle flap (83.82, 86.7, 77.61, 77.81, or 77.91) recorded within 90 days post-CABG were considered to have mediastinitis. Risk of mediastinitis was determined for four AMP regimens: 1stor 2nd generation cephalosporin alone (standard AMP), vancomycin alone (vanc AMP), vancomycin plus standard AMP (extended AMP1), vancomycin plus either an aminoglycoside, 3rd or 4th gen cephalosporin, quinolone, or extended spectrum penicillin (extended AMP2). A logistic regression model controlling for demographics and clinical characteristics as well as mupirocin administration was used to estimate the relative risk of mediastinitis for each AMP regimen.
Results: Among 254 hospitals, between 2007-2010, 178,390 eligible CABG procedures were identified, of which 1777 cases (1.0%) had mediastinitis. Of patients who received standard AMP, mediastinitis was identified in 710 (1.0%); of patients receiving vanc AMP, extended AMP1, and extended AMP2, mediastinitis was identified in 180 (1.3%), 348 (0.9%), and 190 (1.0%), respectively. In a multivariate model controlling for demographic and clinical characteristics, the risk of mediastinitis for those receiving extended AMP1 (RR=0.85, 95% CI 0.74-0.97) or extended AMP2 (RR=0.74, 95% CI 0.62-0.87), was lower compared to standard AMP. Further, among the 47% receiving mupirocin prior to CABG, the risk of mediastinitis was lower compared to those who received no mupirocin (RR=0.79, 95% CI 0.71 0.88).
Conclusion: Extended spectrum AMP regimens (i.e. vancomycin plus standard AMP or vancomycin plus an antibiotic with extended gram-negative spectrum) may reduce CABG SSI risk. Mupirocin may further reduce risk regardless of AMP regimen. Given potential unintended consequences of extended AMP regimens, further study is needed to confirm these findings.
J. Jernigan, None