Multivariable Predictors of Postoperative Cardiac Adverse Events after General and Vascular Surgery: Results from the Patient Safety in Surgery Study

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Abstract
Background Cardiac adverse events (CAEs) are relatively infrequent, but highly lethal, after noncardiac operations. The value of available risk scoring systems is uncertain and these systems can be outdated. We used the Patient Safety in Surgery Study database to develop and test a model to predict patient risk for CAEs after general and vascular surgical operations. Study Design As part of the Patient Safety in Surgery Study, following the National Surgical Quality Improvement Program’s protocol, multiple demographic, preoperative, perioperative, and outcomes variables were measured during a 3-year period. Data from 128 Veterans Affairs medical center hospitals and from 14 academic medical centers on 183,069 patients were used in a logistic regression analysis to model multivariable predictors of serious CAEs (cardiac arrest or acute myocardial infarction within 30 days of operation). Results CAEs occurred in 2,362 patients (1.29%) and of these, 59.44% expired. Multivariable stepwise logistic regression identified 20 independent predictors of CAEs, which excluded most cardiac-specific risk factors. The most important multivariable predictors of CAE were American Society of Anesthesiologists physical status classification, work relative value units of the most complex procedure, age, and type of operation. A risk prediction scoring system using the logistic regression odds ratios proved to be a useful prediction tool when tested using a random sample from the database. Conclusions CAEs after noncardiac operations are relatively infrequent but highly lethal. Operation type and urgency and American Society of Anesthesiologists physical status assessment are important independent predictors of cardiac morbidity, but angina, recent MI, and earlier cardiac operation are not. A prediction scoring system based on the Patient Safety in Surgery Study multivariable odds ratios is likely to be predictive of future events in a similar population requiring noncardiac procedures. This risk model can also serve as a tool to measure quality and effectiveness of care by providers who perform noncardiac operations.