iHOT-12 item analysis: correlations between individual items and overall score within and across time points.

Abstract

The main aim of this study was to analyze correlations between individual international hip outcome tool 12 (iHOT-12) items and overall iHOT-12 score within and across timepoints. A retrospective multicenter hip arthroscopy registry was queried for patients from January 2014 to October 2023 with completed iHOT-12 reports. Pearson coefficient analysis was used to identify correlations between individual iHOT-12 items and overall iHOT-12 score at each timepoint and between preoperative individual iHOT-12 items and postoperative overall iHOT-12 scores. Validity, reliability, and responsiveness of the iHOT-12 were analyzed at each timepoint. Within timepoints, correlations ranged in strength from fair (preoperative maintain fitness level, r = 0.52, P < .00001) to excellent (5-year hip pain after activity, r = 0.93, P < .00001). Correlations increased in strength over time. Across timepoints, correlations ranged in strength from no correlation (2-year maintain fitness level, r = -0.001, P = 0.94) to poor (6-month pushing or lifting heavy objects, r = 0.31, P < .00001). Correlations decreased in strength over time. No ceiling or floor effects were exhibited. The Cronbach alpha for the baseline, 6-month, 1-year, 2-year, and 5-year timepoints were 0.87, 0.96, 0.95, 0.96, and 0.97, respectively. Cohen's d values at 6 months, 1 year, 2 years, and 5 years were 1.19, 1.43, 1.71, and 1.58, respectively. Within timepoints, hip pain after activity had the strongest correlations to overall iHOT-12 score. Across timepoints, correlations between preoperative individual iHOT-12 items and postoperative overall iHOT-12 score were poor and weakened over time, suggesting similar long-term postoperative iHOT-12 scores among both high- and low-scoring preoperative patients. The iHOT-12 demonstrated good validity, reliability, and responsiveness at all timepoints.