Evaluation of the Complication Rate as a Measure of Quality of Care in Coronary Artery Bypass Graft Surgery

OBJECTIVE: To determine whether hospital rankings based on complication rates provide the same information as hospital rankings based on mortality rates. DESIGN: A retrospective study of in-hospital death, complication, and death following complication (failure to rescue). Hospitals were ranked using residuals based on the difference between the observed and the expected number of events (from logistic regression models); rankings were compared using Spearman rank correlations. SETTING: Hospitals performing coronary artery bypass graft (CABG) surgery in the 1991 and 1992 MedisGroups National Comparative Data Bases. PATIENTS AND DATA SETS: Record abstraction data for 16,673 patients who underwent CABG procedures at 57 hospitals, linked with data from the 1991 American Hospital Association Annual Survey. RESULTS: After adjusting for patient admission severity of illness, there were low correlations between hospital rankings based on death or failure to rescue and those rankings based on complication (death vs complication, r = 0.07, P = .58; failure to rescue vs complication, r = -0.22, P = .11). In addition, many hospital characteristics that are generally associated with a higher quality of care were associated with higher complication rates but with expected or lower-than-expected mortality rates. CONCLUSIONS: Hospital rankings based on complication rates provide different information than those based on mortality rates. Until more is known about these differences, complication rates should not be used to judge hospital quality of care in CABG surgery.