2-year cost-effectiveness of total knee replacement: results from the first randomized trial on total knee replacement in addition to non-surgical treatment

Purpose: The number of total knee replacements (TKR) is on the rise. Despite the large number of TKRs performed annually, high-quality evidence on the cost-effectiveness of the procedure compared to non-surgical procedures is missing. The aim of the study was to assess the 2-year cost-effectiveness of TKR followed by non-surgical treatment compared to non-surgical treatment alone. Methods: A total of 100 adults suffering from moderate to severe knee osteoarthritis who were eligible for TKR were randomly assigned to undergo either TKR plus 12 weeks of supervised non-surgical treatment consisting of exercise, education, diet, insoles and pain medication or 12 weeks of supervised non-surgical treatment alone. Effectiveness was measured as change in quality-adjusted life years (QALYs) from baseline to 2 years after randomization, while healthcare costs and use of transfer payments were derived from Danish national registries. Incremental costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated. A probabilistic sensitivity analysis was conducted and the probability of cost-effectiveness was estimated at a 22,665 Euros/QALY threshold. Results: With a mean cost of 23,076 Euros compared to 14,514 Euros over 2 years, TKR followed by non-surgical treatment was more expensive than non-surgical treatment alone. However, treatment with TKR followed by non-surgical treatment was also more effective than non-surgical treatment alone with mean two-year improvement in QALY of 0.195 compared to 0.056. The probability of cost-effectiveness of TKR followed by non-surgical treatment was 7.5% in the base-case scenario increasing to 33.2% when ignoring covariates and missing values within the two years. In the Base-case scenario, TKR plus non-surgical treatment required a cost of 50,607 Euros per QALY gained to be cost-effective. TKR followed by non-surgical treatment was both more expensive and less effective than non-surgical treatment alone when including deaths in the analysis in the base-case scenario. Conclusions: Treatment with TKR followed by nonsurgical treatment is not cost-effective in a 2-year perspective compared to non-surgical treatment alone in patients with moderate to severe knee osteoarthritis. Extending the time horizon to 5 or 10 years may yield different results in favor of the group undergoing TKR.