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 ( range, 0.60-0.76; < .001), except for one correlation between the iHOT-Sport and HAGOS-Sport ( = .058; < .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 <0.90). Minimal detectable change values (group level) ranged from 2.3 to 3.7 (95% CI, 1.7-5.0). All iHOT-33 subscale scores were responsive (ρ range, 0.40-0.58; ≤ .001), except for the iHOT-Job in patients not undertaking treatment (ρ = 0.27; = .001).

Conclusion: All iHOT-33 subscale scores were valid for use in patients with hip/groin pain who were not seeking surgery. Acceptable test-retest reliability was found for all subscale scores at the group level, except the iHOT-Job. All subscale scores, excluding the iHOT-Job, were responsive, regardless of undertaking physical therapist-led treatment or no treatment.