Patient-Reported Outcomes Measurement Information System Mobility Computerized Adaptive Testing Maintains High Correlation and Low Test Burden Compared With Legacy Hip-Specific Instruments in Patients Undergoing Hip Arthroscopy for Femoroacetabular Impingement

Purpose: To evaluate the reliability, construct validity, and responsiveness of the lower extremity–specific Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility (MO) bank in patients who underwent hip arthroscopic surgery for femoroacetabular impingement. Methods: Patients who underwent primary hip arthroscopic surgery at a large academic musculoskeletal specialty center between November 2019 and November 2020 completed the following baseline and 6-month measures: PROMIS MO, PROMIS Pain Interference (PI), PROMIS Physical Function (PF), modified Harris Hip Score, International Hip Outcome Tool 33, visual analog scale, and Single Assessment Numeric Evaluation. Construct validity was evaluated using Spearman correlation coefficients. The number of questions until completion was recorded as a marker of test burden. The percentage of patients scoring at the extreme high (ceiling) or low (floor) for each measure was recorded to measure inclusivity. Responsiveness was tested by comparing differences between baseline and 6-month measures, controlling for age and sex, using generalized estimating equations. Magnitudes of responsiveness were assessed through the effect size (Cohen d). Results: In this study, 660 patients (50% female patients) aged 32 ± 14 years were evaluated. PROMIS MO showed a strong correlation with PROMIS PF (r = 0.84, P <.001), the International Hip Outcome Tool 33 (r = 0.73, P <.001), PROMIS PI (r = –0.76, P <.001), and the modified Harris Hip Score (r = 0.73, P <.001). Neither PROMIS MO, PROMIS PI, nor PROMIS PF met the conventional criteria for floor or ceiling effects (≥15%). The mean number of questions answered (± standard deviation) was 4.7 ± 2.1 for PROMIS MO, 4.1 ± 0.6 for PROMIS PI, and 4.1 ± 0.6 for PROMIS PF. From baseline to 6 months, the PROMIS and legacy measures exhibited significant responsiveness (P <.05), with similar effect sizes between the patient-reported outcome measures. Conclusions: This longitudinal study reveals that in patients undergoing hip arthroscopy, PROMIS MO computerized adaptive testing maintains high correlation with legacy hip-specific instruments, significant responsiveness to change, and low test burden compared with legacy measures, with no ceiling or floor effects at 6-month postoperative follow-up. Level of Evidence: Level IV, retrospective case series.