Reliability and responsiveness of the Swedish short Hip-RSI

Purpose: The aim of this study was to examine test–retest reliability and responsiveness of the short version (6-item) Hip Return to Sport after Injury (Hip-RSI) scale in patients following hip arthroscopy. Methods: The study included 100 hip arthroscopy patients responding to a digital survey including the short version (6-item) Hip-RSI, International Hip Outcome Tool (short version) (iHOT-12) and RTS status 3, 6 and 9 months following surgery. The Hip-RSI was administered twice at 3-month follow-up. Test–retest reliability was evaluated using intraclass correlation coefficients. Responsiveness was tested by correlations between changes in Hip-RSI and iHOT-12 scores and by comparing change in Hip-RSI scores of patients who progressed on the return to sport (RTS) continuum (from return to any sport to return to performance) to patients who did not, using independent samples t-tests. Results: Hip-RSI was found to have excellent test–retest reliability on the individual (intraclass correlation coefficient, ICC [95% confidence interval, CI]: 0.90 [0.83–0.94]) and group level (ICC [95% CI]: 0.95 [0.91–0.97]) with a standard error of measurement of 5.53 and smallest detectable change of 15.3 on the individual and 2.2 on the group level. Hip-RSI was found responsive to change through positive correlations of changes in scores with changes in iHOT-12 scores from 3 to 6 months (r [95% CI]: 0.51 [0.35–0.65]; p < 0.001) and from 3 to 9 months following arthroscopy (r [95% CI]: 0.61 [0.57–0.79); p < 0.001). Further responsiveness was shown by significant mean changes in scores among patients that progressed on the RTS-continuum (3–6 months: 8.6 [95% CI: 3.8– 13.5); 3–9 months: 12.6 [5.6–19.7]). Conclusion: The short version (6-item) Hip-RSI demonstrated excellent test–retest reliability and responsiveness to change in the evaluation of psychological readiness to RTS following hip arthroscopy. Level of Evidence: Level II.