Patient-Reported Outcome Measures and Clinically Important Outcome Values in Hip Arthroscopy: A Systematic Review

Defining success in hip arthroscopy through patient-reported outcome measures (PROMs) is complicated by the wide range of available questionnaires and overwhelming amount of information on how to interpret scores. The minimal clinically important difference (MCID), patient acceptable symptom state (PASS), and substantial clinical benefit (SCB) are collectively known as clinically important outcome values (CIOVs). These CIOVs provide benchmarks for meaningful improvement. The aims of this review were to update the evidence regarding joint-specific PROMs used for hip arthroscopy and to collate available CIOVs in this population.

A systematic review of MEDLINE and Embase databases was performed to identify studies reporting measurement properties of PROMs utilized for hip arthroscopy. Metrics of reliability, validity, and responsiveness were extracted and graded according to an international Delphi study. Questionnaire interpretability was evaluated through CIOVs.

Twenty-six studies were reviewed. One study validated a novel questionnaire, 3 studies validated existing questionnaires, and 22 studies reported CIOVs. The most evidence supporting interpretability was found for the Hip Outcome Score (HOS, 11 studies), modified Harris hip score (mHHS, 10 studies), and International Hip Outcome Tool-12 (iHOT-12, 9 studies). Scores indicative of the smallest perceptible versus substantial clinically relevant changes were reported for the iHOT-12 (12 to 15 versus 22 to 28), iHOT-33 (10 to 12 versus 25 to 26), HOS-Activities of Daily Living (HOS-ADL, 9 to 10 versus 10 to 16), HOS-Sports (14 to 15 versus 25 to 30), and mHHS (7 to 13 versus 20 to 23). Absolute postoperative scores indicative of an unsatisfactory versus a desirable outcome were reported for the iHOT-12 (below 56 to 63 versus above 86 to 88), iHOT-33 (below 58 versus above 64 to 82), HOS-ADL (below 87 to 92 versus above 94), HOS-Sports (below 72 to 80 versus above 78 to 86), and mHHS (below 74 to 85 versus above 83 to 95).

Six questionnaires had reported clinically important outcome thresholds, with the HOS, mHHS, and iHOT-12 having the most information to support score interpretation. Thresholds for the HOS, mHHS, iHOT-12, and iHOT-33 describe desirable absolute PROM scores and minimum and substantial change scores within 5 years following hip arthroscopy. Despite substantial heterogeneity in calculation methodology, included cohorts, and follow-up time, available interpretability values could be meaningfully summarized.

In light of increasing use of PROMs in orthopaedics, a summary of the available CIOVs provides guidance for clinicians in mapping numerical scores from PROMs onto clinical benchmarks.