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

Abstract

BackgroundAlthough 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. MethodsWe 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). ResultsSimultaneous 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). ConclusionSimultaneous 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.