Outcomes for mitral valve surgery among Medicare fee-for-service beneficiaries, 1999 to 2008

Mitral valve surgery in older adults carries with it substantial morbidity and mortality risks, yet there are a paucity of national surveillance data. Therefore, we sought to determine trends in hospitalization rate, readmission, and mortality among Medicare fee-for-service (FFS) patients undergoing mitral valve surgery.

Inpatient Medicare standard analytic files were used to identify 100% of FFS patients aged ≥ 65 years who underwent mitral valve surgery between 1999 and 2008. We constructed a denominator file from Medicare administrative data to report hospitalization rates for mitral valve surgery (total and isolated) per 100 000 beneficiary-years. For isolated mitral valve surgery, 30-day readmission, 30-day mortality, and 1-year mortality outcomes were ascertained through corresponding inpatient and vital status files, and risk-standardized rates were calculated adjusting for age, sex, race, and comorbidities. During 1999 to 2008, the overall rate of mitral valve surgery per 100K beneficiary-years declined (56/100K to 51/100K), and the proportion of patients undergoing mitral valve repair (versus replacement) increased (24.7% to 46.9%, P<0.001). For isolated mitral valve surgery, there were significant declines in risk-adjusted 30-day mortality (8.1% to 4.2%, P<0.001 for trend) and 1-year mortality (15.3% to 9.2%, P=0.003 for trend) and a slight decline in risk-adjusted 30-day readmission (23.0% to 21.0%, P=0.035 for trend) over the study period. Mortality rates decreased in all age, sex, and race subgroups, and among patients undergoing mitral valve repair or replacement, but remained higher among patients aged ≥ 85 years, women, and nonwhites.

Between 1999 and 2008, outcomes after isolated mitral valve surgery significantly improved among Medicare FFS patients. Disparities among demographic subgroups indicate potential areas for quality improvement.