Total or partial knee replacement? Cost-utility analysis in patients with knee osteoarthritis based on a 2-year observational study

The objective of this study was to evaluate incremental cost-utility of total knee replacement (TKR) versus unicompartmental knee arthroplasty (UKA) in patients with knee osteoarthritis (OA) of the medial compartment. A 2-year non-randomised prospective observational cohort study was conducted in unicompartmental knee osteoarthritis patients scheduled for TKR (n = 431) or UKA (n = 102). Costs were identified using administrative databases and health outcomes were measured using the SF-36 and the Oxford knee score (OKS) 1 week before, 6 months after, and 2 years after surgery. The incremental cost-utility ratio (ICUR) for TKR versus UKA was calculated and its 95% confidence interval estimated using a nonparametric bootstrapping technique. Cost-effectiveness acceptability curves were constructed from different perspectives. On average, from the societal perspective, the ICUR was US $65,245 per quality-adjusted life-year (QALY). In the scenario with costs calculated from the perspective of patients, the ICUR was $60,382/QALY. This value decreased to $4,860/QALY in the scenario with costs calculated from the governmental perspective. However, the 95% confidence interval of ICURs cannot be defined because more than 5% bootstrapped samples fell into the upper left quadrant of the cost-effectiveness plane from all three perspectives. Based on the 2-year data, TKR gained more QALYs at higher costs compared to UKA. A long-term prospective study is necessary to determine cost-effectiveness of TKR and UKA.