Risk Adjustment in the California Joint Replacement Registry: Is Patient Complexity Accurately Assessed in Academic Versus Nonacademic Hospitals?

We sought to report on the differences in observed versus expected arthroplasty outcomes between academic and nonacademic hospitals in a large joint registry. We utilized the California Joint Replacement Registry’s data and risk adjustment model.

Observed versus expected hip and knee arthroplasty complications were utilized to assess hospital and surgeon risk-adjusted complication rates (RACRs). Based on a hospital and surgeon RACR, each was assigned a performance rating (“worse,” “expected,” “better”). Associations between academic status and performance ratings, rates of individual complications, prevalence of risk factors associated with increased complication rates, and differences in complication rates were calculated.

A higher percentage of academic providers had “worse” than expected ratings, whereas a higher percentage of nonacademic providers had “expected” and “better” than expected ratings ( P = .011) based on the observed versus expected complication rates. There was a higher incidence of patients with congestive heart failure and an elevated American Society of Anesthesiologists classification in academic institutions ( P = .0001). The complication rate was higher in academic institutions for all total knee arthroplasties ( P < .0016).

We identified disparities in RACRs between nonacademic and academic institutions. This may reflect the difficulty of fully adjusting for medical risk and surgical complexity in a large arthroplasty database.