Does Achieving the Minimal Clinically Important Difference in the Knee Injury and Osteoarthritis Outcome Score for...

Managed care systems have expressed interest in using patient-reported outcome measures (PROMs) to determine surgical eligibility for total knee arthroplasty (TKA). The relationship between PROMs and patient satisfaction following TKA is an area of active research. We asked (1) what is the relationship between patient satisfaction and achieving minimal clinically important difference (MCID) in Knee Injury Osteoarthritis Outcomes Survey for Joint Replacement (KOOS, JR) at 1 year post-TKA, (2) what is the optimal change in KOOS, JR from preoperative to 1-year post-TKA that predicts patient satisfaction, and (3) are there additional preoperative factors that influence patient satisfaction following TKA.

A retrospective cohort study analyzed patients who underwent primary TKA at a single ambulatory surgery center. Patients completed KOOS, JR and Veterans Rand 12-Item Health Survey (VR-12) at baseline, 12 weeks, 6 months, and 1 year postoperatively. Satisfaction was assessed using a Likert scale. Logistic regression, best-fit modeling, and classification and regression tree analyses were performed to determine predictors of satisfaction.

Among 600 patients, 93.7% were satisfied. MCID was met in 71.8% of satisfied patients vs 44.7% of unsatisfied patients (P < .001). Preoperative to 1-year change in KOOS, JR (odds ratio 1.09, P < .001) and preoperative VR-12 mental component scores (odds ratio 1.05, P = .007) predicted satisfaction. No change threshold for KOOS, JR predicted satisfaction.

While KOOS, JR improvement correlated with satisfaction, achieving MCID was not a reliable predictor. Preoperative factors, including VR-12 mental component scores, may better identify patients likely to be satisfied post-TKA. Further research on larger cohorts is needed to refine PROM-based eligibility criteria.