A Time-Driven Activity-Based Costing Analysis of Simultaneous Versus Staged Bilateral Total Hip Arthroplasty and Total Knee Arthroplasty

Abstract

Background: Although studies have compared the claims costs of simultaneous and staged bilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA), whether a simultaneous procedure is cost-effective to the facility remains unknown. This study aimed to compare facility costs and perioperative outcomes of simultaneous vs staged bilateral THA and TKA.

Methods: We reviewed a consecutive series of 560 bilateral THA (170 staged and 220 simultaneous) and 777 bilateral TKA (163 staged and 451 simultaneous). Itemized facility costs were calculated using time-driven activity-based costing. Ninety-day outcomes were compared. Margin was standardized to unadjusted Medicare Diagnosis Related Group payments (simultaneous, $18,523; staged, $22,386). Multivariate regression was used to determine the independent association between costs/clinical outcomes and treatment strategy (staged vs simultaneous).

Results: Simultaneous bilateral patients had significantly lower personnel, supply, and total facility costs compared with staged patients with no difference in 90-day complications between the groups. Multivariate analyses showed that overall facility costs were $1,210 lower in simultaneous bilateral THA (P < .001) and $704 lower in TKA (P < .001). Despite lower costs, margin for the facility was lower in the simultaneous group ($6,569 vs $9,225 for THA; $6,718 vs $10,067 for TKA; P < .001).

Conclusion: Simultaneous bilateral TKA and THA had lower facility costs than staged procedures because of savings associated with a single hospitalization. With the increased Medicare reimbursement for 2 unilateral procedures, however, margin was higher for staged procedures. In the era of value-based care, policymakers should not penalize facilities for performing cost-effective simultaneous bilateral arthroplasty in appropriately selected patients.

Keywords: bilateral procedure; facility cost; health policy; time-driven activity-based costing; total hip arthroplasty; total knee arthroplasty.