Med-Score 24: A multivariable prediction model for poststernotomy mediastinitis 24 hours after admission to the intensive care unit

Objectives: Mediastinitis is a serious complication of heart surgery. In this study, we developed a bedside risk score for poststernotomy mediastinitis. Methods: Data were prospectively collected from 4625 patients admitted to our intensive care unit after heart surgery (January 2005-June 2011). Mediastinitis was defined according to Centers for Disease Control and Prevention criteria. A logistic model was constructed in a randomly selected subgroup of 2618 patients and validated in a second cohort of 1352, as well as in a prospective cohort of 2615 (June 2011-December 2015). Model discriminatory power was assessed according to the area under the receiver operating characteristic curve (AUROC). The beta coefficients of the model were used to define 3 levels of mediastinitis risk as a score designated Med-Score 24. Its performance to predict mediastinitis was compared with that of the logistic EuroSCORE and Society of Thoracic Surgeons score. Results: Ninety-four (2.36%) patients developed mediastinitis. The risk factors identified as predictive of mediastinitis (AUROC 0.80) were 4 preoperative variables (age>70 years, chronic obstructive lung disease, obesity, and antiplatelet therapy) and 3 perioperative variables (prolonged ischemia, emergency reoperation, and prolonged intubation). AUROCs for the Society of Thoracic Surgeons score and logistic EuroSCORE were 0.63 and 0.55, respectively, both differing significantly from the area calculated for Med-Score 24 (P<.001). Conclusions: The score developed showed excellent predictive power 24 hours after admission to the intensive care unit for mediastinitis risk. This simple tool helps stratify patients according to this risk, thus identifying high-risk patients for preventive measures. In our patient cohort, Med-Score 24 performed better than other scores used for this purpose.