Defining Clinically Significant Outcome Thresholds for the Patient-Reported Outcomes Measurement Information System (PROMIS) at 2 Years After Gluteus Medius and/or Minimus Repair.

Background: Clinically significant outcome (CSO) thresholds are invaluable to the interpretation of patient-reported outcomes (PROs). The Patient-Reported Outcomes Measurement Information System (PROMIS) is gaining popularity among the orthopaedic community; however, CSO thresholds for PROMIS are yet to be defined for outcomes after gluteus medius and/or minimus (GM) repair.

Purpose: To (1) define CSO thresholds for PROMIS-Pain Interference (PROMIS-PI) and PROMIS-Physical Function (PROMIS-PF) after GM repair, (2) correlate these PROMIS scores with legacy hip-specific PROs, and (3) quantify their floor and ceiling effects.

Study Design: Case series; Level of evidence, 4.

Methods: Consecutive patients who underwent primary GM repair between September 2017 and June 2021 with completed PROMIS at minimum 2-year follow-up were evaluated. The minimal clinically important difference, Patient Acceptable Symptom State, and substantial clinical benefit thresholds were defined for the PROMIS-PI and PROMIS-PF as well as for legacy PROs: Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Hip Outcome Score-Sports Subscale (HOS-SS); modified Harris Hip Score (mHHS); 12-item International Hip Outcome Tool (iHOT-12); and the visual analog scale (VAS) for pain and satisfaction. Pearson correlations were performed between PROMIS scores and legacy PROs. Rates of floor and ceiling effects were quantified.

Results: Overall, 107 patients (81.7% follow-up compliance; mean age, 59.8 ± 8.8 years; 92.5% female; mean body mass index, 28.6 ± 6.3 kg/m) were included in the analysis. GM tears were partial thickness in 56.1% of cases and treated endoscopically in 64.5% of cases. The minimal clinically important difference, Patient Acceptable Symptom State, and substantial clinical benefit thresholds, respectively, were as follows: PROMIS-PI (-4.6, 56.0, 52.6), PROMIS-PF (3.5, 42.7, 43.7), HOS-ADL (10.7, 68.2, 78.6), HOS-SS (16.5, 58.6, 60.6), mHHS (9.0, 64.3, 71.5), iHOT-12 (14.2, 63.6, 69.4), VAS pain (-16.1, 34.9, 28.1), and VAS satisfaction (not applicable, 70.9, 93.6). Moderate to strong correlations were observed between the PROMIS and legacy PROs. The PROMIS-PI showed a significant postoperative floor effect of 18.7%.

Conclusion: Study findings indicated that the PROMIS is effective for use in GM repair patients, given the moderate-to-strong correlations between the PROMIS and legacy hip-specific PROs, the mostly limited floor and ceiling effects, and large effect sizes. Use of PROMIS instead of legacy PROs may aid in limiting survey burden.