Risk models including high-risk cardiovascular procedures: clinical predictors of mortality and morbidity

Abstract

Objective: While isolated coronary artery bypass grafting (CABG) poses major risks as well as benefits to cardiovascular surgery, procedures such as thoracic aortic surgery and combined CABG surgeries are also important contributors to mortality and morbidity. The objective of this study was to create and validate risk models including high-risk cardiovascular procedures to improve quality.

Methods: The Japan Cardiovascular Surgery Database of patients enrolled cardiovascular surgical patients between January 2005 and December 2007. Data were collected at presentation and by physician review of clinical records and were verified through third-party surgeons' auditing. We analyzed 36780 procedures in 120 hospitals. Using logistic regression, risk models were generated and validated by split-sample validation.

Results: In this analysis, 11948 procedures were isolated CABG, 11760 were valve surgeries, and 8440 were thoracic aortic surgeries. In a 30-day operative mortality risk model, 37 variables were significantly associated with outcome. In comparison to isolated CABG, the odds ratios (ORs) for a 30-day mortality were 1.81 for valve surgery (2.62 in mitral valve replacement and 2.72 in aortic valve plus mitral valve procedures) and 2.36 for thoracic aortic surgery (4.34 if indicated by rupture, 3.16 if involving only arch, 4.38 if involving distal aorta, 3.75 if descending, and 5.97 if thoraco-abdominal aorta). CABG combined with other procedures (n=3599) had increased risks in each morbidity risk model (OR: 1.21 in reoperation, 1.60 in stroke, 1.23 in dialysis, 1.97 in infection, and 1.40 in prolonged ventilation). The predictive power of our models is valued by a C-statistic of 0.830 for a 30-day postoperative mortality, 0.639 for reoperation, 0.726 for stroke, 0.817 for dialysis, 0.692 for infection, and 0.796 for prolonged ventilation.

Conclusions: Though performance of isolated CABG surgery was stable in this era, CABG combined with valve or thoracic aortic surgery was still a high-risk procedure. Given better recognition of high patient risk from these models, earlier targeted perioperative interventions may reduce adverse effects.