Comparing Risk Assessment Between Payers and Providers: Inconsistent Agreement in Medical Comorbidity Records for Patients Undergoing Total Joint Arthroplasty.

Background: The proper risk adjustment for total hip arthroplasty (THA) and total knee arthroplasty (TKA) relies on an accurate assessment of comorbidity profiles by both the payer and the institution. The purpose of this study was to determine how strongly comorbidities tracked by our institution agreed with the same comorbidities reported by payers in patients undergoing THA and TKA.

Methods: All patients of a single payer undergoing primary THA and TKA at a single institution between January 5, 2021 and March 31, 2022 were included (n = 876). There were 8 commonly collected medical comorbidities obtained from institutional medical records and matched with patient records reported by the payer. Fleiss Kappa tests were used to determine agreement of payer data with institutional records. There were 4 medical risk calculations collected from our institutional records and compared with an insurance member risk score reported by the payer.

Results: Comorbidities reported by the institution differed significantly from those reported by payers, with Kappa varying between 0.139 and 0.791 for THA, and 0.062 and 0.768 for TKA. Diabetes was the only condition to demonstrate strong agreement for both procedures (THA; k = 0.791, TKA; k = 0.768). The insurance member risk score demonstrates the closest association with total cost and surplus for THA regardless of insurance type and for TKA procedures paid for with private commercial insurance.

Conclusion: There is a lack of agreement between medical comorbidities within payer and institutional records for both THA and TKA. These differences may put institutions at a disadvantage within value-based care models and when optimizing patients perioperatively.