Predicting hospital mortality and analysis of long-term survival after major noncardiac complications in cardiac surgery patients

Abstract

Background: This study was designed to investigate the incidence of and early and midterm outcomes after major complications in cardiac surgery patients. We determined independent predictors of operative mortality to create a model for prediction of outcome. A particular focus was the fate of patients after the occurrence of these complications.

Methods: Prospectively collected data of 6,641 patients (mean age, 64 ± 14 years; n = 2,499 female [38%]) undergoing cardiac surgery between January 1998 and December 2006 were retrospectively analyzed. Outcome measures were six index complications: respiratory failure, sepsis, dialysis-dependent renal failure, mediastinitis, gastrointestinal complication, and stroke; and their impact on operative mortality, hospital length of stay, and midterm survival using multivariate regression models. The discriminatory power was evaluated by calculating the area under the receiver operating characteristic curves (C statistic).

Results: A total of 1,354 complications were observed in 826 (12.4%) patients: respiratory failure (n = 634; 9.5%), sepsis (n = 202; 3%), stroke (n = 163; 2.5%), dialysis-dependent renal failure (n = 145; 2.2%), mediastinitis (n = 111; 1.7%), and gastrointestinal complication (n = 99; 1.5%). Overall operative mortality was 20% and correlated with the number of complications (single, 12.0%; n = 58 of 485; double, 25.5%; n = 52 of 204; ≥ 3, 40.1%; n = 55 of 137). Ten preoperative and five postoperative predictors of operative mortality were identified and included in the logistic model, which accurately predicted outcome (C statistic, 0.866). One-year survival was less than 50% in patients with three or more complications and a length of stay greater than 60 days.

Conclusions: With a worsening in the risk profile of patients undergoing cardiac surgery, an increasing number of patients develop major complications leading to increased length of stay and mortality, which is correlated to the number and severity of these complications. Our predictive model based on preoperative and postoperative variables allowed us to determine with accuracy the operative mortality in critically ill patients after cardiac surgery. One-year survival after multiple complications and prolonged length of stay remains marginal.