Defining Failure in Primary Total Joint Arthroplasty: The Minimal Clinically Important Difference for Worsening Score

We define the value of the Minimal Clinically Important Difference for Worsening (MCID-W) for Patient-Reported Outcomes Measurement Information System Physical Function short form 10-a (PROMIS-PF-10a) score for primary total joint arthroplasty (TJA) of the hip and knee and describe the risk factors for patients scoring worse than the MCID-W.

This retrospective study was performed using 3414 primary TJA patients. PROMIS-PF-10a scores were collected at the preoperatively and postoperatively, and patients were classified based on reaching Minimal Clinically Importance Difference for Improvement (MCID-I), MCID-W, or "no significant change" after TJA (scores betweex`n MCID-W and MCID-I). MCID-W and MCID-I values were determined by a distribution method. The association between numerous variables and scoring worse than the MCID-W of PROMIS-PF-10a was then evaluated through multiple logistic regression. A threshold for preoperative PROMIS-PF-10a score predicting decline past MCID-W was determined using the Youden index and receiver operating characteristic curve.

The MCID-W for TJA was -1.89. Notably, increasing length of stay (odds ratio [OR] 1.073, 95% confidence interval [CI] 1.029-1.119, P < .001) and increasing preoperative PROMIS-PF-10a scores (OR 1.117, 95% CI 1.091-1.144, P < .001) were associated with increased likelihood of decline past the MCID-W of the PROMIS-PF-10a for TJA compared with patients who achieved the MCID-I. A community hospital with a dedicated joint replacement center was associated with a decreased risk for decline past the MCID-W (OR 0.601, 95% CI 0.402-0.899; P = .013).

We described the MCID-W value (-1.89) for the PROMIS-PF-10a questionnaire for knee and hip TJA and associated patient- and hospital-level risk factors for failure after TJA. Healthcare funding initiatives should be directed toward modifiable factors associated with clinically significant worse outcomes after TJA.