Background: Knee cartilage lesions increase the risk of developing osteoarthritis (OA), and may eventually result in a total knee replacement (TKR). There is currently no consensus on the optimal treatment of cartilage lesions. ChondroCelect® (CC) is a cell-based therapy approved for use in autologous chondrocytes implantation (ACI) to treat symptomatic cartilage defects of the femoral condyle. Its capacity to safely restore good-quality cartilage was demonstrated in a randomized controlled trial (RCT) versus the surgical procedure microfracture (MFX).
Objective: This study investigated the cost utility of CC used in ACI compared with MFX to treat symptomatic knee cartilage lesions in Belgium.
Methods: A decision tree model comparing CC with MFX over a 40-year horizon was developed in TreeAge Pro™. The key timepoints of the model were (i) clinical assessment 5 years after initial intervention (success or no success, with or without re-operation); (ii) development of OA at 15 years (yes/no); (iii) need for TKR at 20 years (yes/no); and (iv) need for prosthesis revision at 35 years (yes/no). Clinical data provided by the RCT of CC versus MFX were the clinical success (response) rate based on the Knee injury and Osteoarthritis Outcome Score (KOOS) at 36 months (82.9% vs 62.0%; p = 0.048) and the proportion of good structural repair/presence of hyaline cartilage based on International Cartilage Repair Society (ICRS II) visual item at 12 months (44.9% vs 23.2%; p = 0.023). Utility scores by surgery outcome were derived from the SF-36 questionnaire responses collected in the RCT. Conservative assumptions related to the incidences of OA, TKR and prosthesis revision relied on a literature search. A patient chart review (n = 82) provided follow-up costs by surgery outcome. National tariffs were applied to direct medical resources used (healthcare payer perspective, year 2008 costs). Annual discounting was applied to costs (3%) and effects (1.5%) as recommended by the Belgian pharmacoeconomic guidelines.
Results: The incremental cost per QALY gained for CC compared with MFX was €16,229, with a difference in costs of €20,802 and 1.282 QALYs gained. Sensitivity analyses indicated that the key model drivers were the proportion of patients with hyaline cartilage and the correlation between hyaline cartilage formation and later avoidance of OA. Probabilistic sensitivity analyses showed robustness of the results, with 80% of the simulations below the usual UK National Institute for Health and Clinical Excellence (NICE) threshold of €22,000 per QALY.
Conclusions: Assuming a good correlation between high-quality cartilage repair and avoidance of OA at a later stage, the benefits of the cell therapy CC over MFX in terms of QALYs gained and OA-related costs avoided appear real. Further research is required to explore long-term effects of cartilage repair and reduce uncertainty on quality of life of patients with OA before and after joint replacement.