The Validity, Reliability, and Responsiveness of the International Hip Outcome Tool–33 (iHOT-33) in Patients With Hip and Groin Pain Treated Without Surgery

Background: The International Hip Outcome Tool–33 (iHOT-33) was developed to evaluate patients seeking surgery for hip and/or groin (hip/groin) pain and may not be appropriate for those seeking nonsurgical treatment. Purpose: To evaluate the psychometric properties of the iHOT-33 total (iHOT-Total) score and all subscale scores in adults with hip/groin pain who were not seeking surgery. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: Patients with hip/groin pain who were not seeking surgery were recruited from 2 ongoing studies in Australia. Semistructured one-on-one interviews assessed content validity. Construct validity was assessed by testing hypothesized correlations between iHOT-33 and Copenhagen Hip and Groin Outcome Score (HAGOS) subscale scores. Test-retest reliability was assessed in patients not undertaking treatment and who reported “no change” in their Global Rating of Change (GROC) score at 6-month follow-up. Scores were reliable at group and individual levels if intraclass correlation coefficients (ICCs) were ≥0.80 and ≥0.90, respectively. Scores were responsive if Spearman rank correlations (ρ) between the change in the iHOT-33 score and the GROC score were ≥0.40. Results: In total, 278 patients with hip/groin pain (93 women; mean age, 31 years) and 55 pain-free control participants (14 women; mean age, 29 years) were recruited. The iHOT-33 demonstrated acceptable content validity. Construct validity was acceptable, with all hypothesized strong positive correlations between iHOT-33 and HAGOS subscale scores confirmed (r range, 0.60-0.76; P < .001), except for one correlation between the iHOT-Sport and HAGOS-Sport (r = .058; P < .001). All scores were reliable at the group level, except for the iHOT-33 job subscale (iHOT-Job) (ICC range, 0.78-0.88 [95% CI, 0.60-0.93]). None of the subscales met the criteria for adequate reliability for use at the individual level (all ICCs