The patient acceptable symptomatic state for commonly used outcome scores 10 years after matrix-associated autologous chondrocyte implantation

Purpose: To determine the Patient Acceptable Symptomatic State (PASS) thresholds for the Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), Lysholm and EuroQol 5 Dimensions (EQ-5D) scores and to identify predictors of PASS at 10 years after matrix-associated autologous chondrocyte implantation (M-ACI). Methods: Patients who underwent M-ACI for chondral defects of the knee between 2011 and 2015 were prospectively evaluated. KOOS, IKDC, Lysholm and EQ-5D scores and anchor-based questions were assessed at baseline and at least 10 years post-operatively. PASS thresholds were determined using receiver operating characteristic (ROC) curve analyses. Multivariable binomial regression analysis was performed to determine the effect of sex, body mass index (BMI), articular cartilage maturation status and the presence of more than one previous knee surgery on the likelihood of achieving PASS. Results: A total of 112 patients who met the inclusion criteria were evaluated at a mean of 11.3 +/- 1.2 years post-operatively, with a mean age of 29.2 +/- 11.0 years. The PASS thresholds for the aforementioned PROMs at 10 years were 61.9 for KOOS (Symptoms 51.8, Pain 79.2, Activities of Daily Living 87.5, Sport 57.5 and Quality of Life 59.4), 59.7 for IKDC, 61.5 for Lysholm and 82.5 for EQ-5D. The ROC curve showed good to excellent predictive value with an area under the curve (AUC) of 0.76-0.84. Male gender (odds ratio [OR] = 3.1; p = 0.016) and BMI between 20 and 29 (OR = 3.9; p = 0.004) had a positive predictive value for achieving PASS at long-term follow-up. Conclusions: The present study determined long-term PASS thresholds for KOOS, IKDC, Lysholm and EQ-5D scores in patients undergoing M-ACI for cartilage repair at the knee. Male gender and a BMI of 20-29 were positive predictors of the likelihood of achieving PASS at 10 years. The identified PASS thresholds are critical for assessing clinical outcomes, evaluating procedural efficacy for regulatory considerations, and planning sample sizes for prospective, controlled studies. Level of Evidence Level IV.