Cost‐Effectiveness of Group‐Based Outpatient Physical Therapy After Total Knee Replacement: Results From the Economic Evaluation Alongside the ARENA Multicenter Randomized Controlled Trial

Objective To assess the cost‐utility and cost‐effectiveness of a group‐based outpatient physical therapy intervention delivered 6 weeks after primary total knee replacement (TKR) compared with usual care, alongside the Activity‐Orientated Rehabilitation Following Knee Arthroplasty (ARENA) multicenter, randomized, controlled trial. Methods The economic analyses were performed from the perspective of the health and social care payer. We collected resource use for health and social care and productivity losses and patient outcomes for 12 months after surgery to derive costs and quality‐adjusted life years (QALYs). Results were expressed in incremental cost‐effectiveness ratios (ICERs), and incremental net monetary benefit statistics (INMBs) for a society willingness‐to‐pay (WTP) threshold of £20,000 per QALY gained, with sensitivity analyses to model specification and perspective. Results The cost of the ARENA physical therapy classes was mean ± SD £179 ± 39 per patient. Treatment in the year following surgery cost was, on average, £1,739 (95% confidence interval [95% CI] –£742, £4,221) per patient in the intervention group (n = 89), which was an additional £346 (95% CI £38, £653) per patient compared with usual care (n = 91) (£1,393 [95% CI –£780, £3,568]). QALY benefits were 0.0506 higher (95% CI 0.009, 0.09) in the intervention group, corresponding to an additional 19 days in “perfect health.” The ICER for the intervention group was £6,842 per QALY gained, and the INMB was £665 (95% CI £139, £1,191), with a 92% probability of being cost‐effective, and no less than 73% in all sensitivity analysis scenarios. Conclusion The addition of group‐based outpatient physical therapy classes to usual care improves quality of life and is a cost‐effective treatment option following TKR for a society WTP threshold of £20,000 per QALY gained.