30-day readmissions after coronary artery bypass graft surgery in New York State.

OBJECTIVES: The aim of this study was to identify reasons for and predictors of readmission.
BACKGROUND: Short-term readmissions have been identified as an important cause of escalating health care costs, and coronary artery bypass graft (CABG) surgery is 1 of the most expensive procedures.
METHODS: We retrospectively analyzed 30-day readmissions for 33,936 New York State patients who underwent CABG surgery between January 1, 2005, and November 30, 2007. The main reasons for readmission (principal diagnoses) and the significant independent predictors of readmission were identified. The hospital-level relationship between risk-adjusted mortality rate and risk-adjusted readmission rate was explored to determine the value of readmission rate as a complementary measure of quality.
RESULTS: The most common reasons for readmission were post-operative infection (16.9%), heart failure (12.8%), and "other complications of surgical and medical care" (9.8%). Increasing age, female sex, African-American race, higher body mass index, numerous comorbidities, 2 post-operative complications (renal failure and unplanned cardiac reoperation), Medicare or Medicaid status, discharges to a skilled nursing facility, saphenous vein grafts, and longer lengths of stay were all associated with higher rates of readmission. The correlation between the risk-adjusted 30-day readmission rate of hospitals and risk-adjusted in-hospital/30-day mortality rate was 0.32 (p = 0.047). The range across hospitals in the readmission rate was from 8.3% to 21.1%.
CONCLUSIONS: The 30-day readmission rate for CABG surgery remains high, despite decreases in short-term mortality. Patients with any of the numerous risk factors for readmission should be closely monitored. Hospital readmission rates are not highly correlated with mortality rates and might serve as an independent quality measure.