Cost analysis of isolated mitral valve surgery in the United States

Within the field of cardiac surgery, several strategies have been adopted in an effort to address contributors to increasing health care costs. Limited data are available on cost analysis within the field of mitral valve surgery. The purpose of our investigation was to analyze cost differences between mitral valve repair and replacement.

The analysis was based on the subset of patients with isolated mitral valve repair or replacement (International Classification of Diseases, ninth revision, clinical codes 35.12, 35.23, and 35.24) using data from the 2005 to 2008 Nationwide Inpatient Sample database, which is the largest all-payer database in the United States. We examined the selective contribution of patient demographics, hospital characteristics, and postoperative complications to cost by using hierarchical linear mixed models. We used mixed effects logistic regression models to identify factors that influence extreme cost expenditures in patients undergoing mitral valve surgery.

Independent predictors of increased cost for both repair and replacement on multivariable analysis included increased age, prior myocardial infarction, heart failure, neurologic deficit, renal disease, emergent status, and Medicare or Medicaid insurance type. The presence of postoperative complications also predicted increased costs. However, the model for repair only yielded a reduction in variability of 13%, while the model for replacement produced a reduction of 22%.

In this analysis, the most important contributors to cost for mitral valve repair and replacement are preoperative patient comorbidities, most notably history of myocardial infarction and heart failure, emergent admission status, and postoperative complications. The variables in our model failed to account for a large proportion of the variability in cost. This would suggest that future analyses exploring differential procedure costs between hospitals must look for factors beyond patient baseline characteristics and postoperative outcomes.