The influence of implant survival on cost-effectiveness in total knee arthroplasty: a patient-level discrete-event simulation study

BACKGROUND: Although several studies have evaluated the cost-effectiveness of total knee arthroplasty (TKA) compared with conservative treatment, few have explored how implant revision rates may influence its long-term cost-effectiveness. The objective of this study was to evaluate the impact of implant revision rates on quality of life and cost-effectiveness in patients undergoing TKA. METHODS: A cost-utility analysis from a healthcare system perspective was conducted using an individualized discrete-event simulation model parameterized with data from a Spanish cohort of patients undergoing TKA. Quality-adjusted life years were calculated with the SF-6D index, and implant alternatives were compared by assigning age- and sex-specific revision rates to each simulated patient while projecting long-term quality of life and life expectancy according to general population standards. The prosthetic models compared were those associated with the highest (WorstKnee) and lowest (BestKnee) revision rates in the UK National Joint Registry. The primary outcome was the incremental cost-effectiveness ratio. Secondary analyses included budget impact and deterministic sensitivity analyses. RESULTS: The projected quality-adjusted life expectancy over 15 years was 9.767 QALYs for WorstKnee, compared with 10.004 QALYs for BestKnee. The incremental cost-effectiveness ratio was €6,219/QALY, which remained below the cost-effectiveness thresholds commonly used in Spain. Use of BestKnee was associated with an additional cost of €332.3 M over 15 years; however, it also led to a substantial reduction in revision surgeries, with 27,878 fewer procedures performed, resulting in gradual cost savings over time. CONCLUSION: Within the price ranges currently observed in the Spanish National Health System, total knee prostheses associated with lower revision rates provide a favorable long-term cost-effectiveness profile and may reduce future revision burden despite their higher acquisition cost.