Risk-adjusted hospital outcomes in elective carotid artery surgery in patients with Medicare.

Background: The risk-adjusted outcomes by hospital of elective carotid endarterectomy that is inclusive of inpatient and 90-day postdischarge adverse outcomes have not been studied.

Methods: We studied Medicare inpatients to identify hospitals with 25 or more qualifying carotid endarterectomy cases between 2012-2014. Risk-adjusted prediction models were designed for adverse outcomes of inpatient deaths, 3-sigma prolonged duration-of-stay outliers, 90-day postdischarge deaths without readmission, and 90-day postdischarge associated readmissions. Standard deviations of predicted overall adverse outcomes were computed for each hospital. Hospital-specific z scores and risk-adjusted adverse outcomes were calculated.

Results: There were 77,086 carotid endarterectomy patients from 960 hospitals complicated by 191 inpatient deaths (0.25%), 4,436 prolonged duration of stay (5.8%), 457 90-day postdischarge deaths (0.6%), and 7,956 90-day postdischarge associated readmissions (10.3%). In the 90-day postdischarge associated readmission patients, an additional 561 patients died after readmission, for total deaths of 1,209 (1.6%) for the study period, and 11,928 (15.5%) patients had one or more adverse outcomes. There were 29 best-performing hospitals (3.0%) with z scores of -2.0 or less (P < .05) with a median rate of risk-adjusted adverse outcomes of 7.1%. A total of 61 suboptimal performers (6.3%) had z scores of +2.0 or greater (P < .05) with a median rate of risk-adjusted adverse outcome rate of 26.4%.

Conclusion: Hospital risk-adjusted adverse outcome rates for carotid endarterectomy are highly variable. Comparisons of hospital performance define the opportunity for improvement.