The use of patient-reported outcome measures to guide referral for hip and knee replacement: Part 2 – a cost-effectiveness analysis

Aims: To assess how the cost-effectiveness of total hip replacement (THR) and total knee replacement (TKR) vary with age, sex and pre-operative Oxford Hip or Knee Score (OHS/OKS) and identify the patient groups for whom THR/TKR is cost-effective. Methods: We conducted a cost-effectiveness analysis using a Markov model from a UK NHS perspective, informed by published analyses of patient-level data. We assessed the cost-effectiveness of THR and TKR in adults with hip or knee osteoarthritis compared with having no arthroplasty surgery during the 10-year time horizon. Results: THR and TKR cost <£7,000 per quality-adjusted life-year (QALY) gained at all pre-operative scores below the absolute referral thresholds calculated previously (40 for OHS and 41 for OKS). Furthermore, THR cost <£20,000/QALY for patients with OHS of ≤45, while TKR was cost-effective for patients with OKS of ≤43, since the small improvements in quality of life outweighed the cost of surgery and any subsequent revisions. Probabilistic and one-way sensitivity analyses demonstrated that there is little uncertainty around the conclusions. Conclusions: If society is willing to pay £20,000 per QALY gained, THR and TKR are cost-effective for nearly all patients who currently undergo surgery, including all patients up to the absolute referral thresholds.