Validity and Reliability of the Thai Version of the International Hip Outcome Tool in Young to Middle-Aged Physically Active Adults With Hip Disorders

BACKGROUND: The International Hip Outcome Tool (iHOT-33), which is a self-administered questionnaire that contains 33 questions, was developed to evaluate young to middle-aged physically active adults with hip pathology. PURPOSE: To translate and cross-culturally adapt the iHOT-33 to create a Thai version of the iHOT-33 (TH-iHOT-33) and to determine the validity and reliability of the TH-iHOT-33. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Translation and cross-cultural adaptation of the iHOT-33 were performed according to international guidelines. Patients aged 18 to 60 years with hip disorders who had a score ≥4 on a modified version of the Tegner activity scale completed the TH-iHOT-33 twice, 2 weeks apart. The Thai versions of the HOOS (Hip disability and Osteoarthritis Outcome Score) and EQ-5D-5L (European Quality of Life–5 Dimensions–5 Levels) were also completed at baseline. At 2 weeks, the Global Perceived Effect scale was completed in addition to the TH-iHOT-33. The statistical testing for validity included construct validity and hypotheses testing. Internal consistency, test-retest reliability, and measurement error were analyzed to determine reliability. RESULTS: The iHOT-33 was successfully translated and cross-culturally adapted to create the TH-iHOT-33. Seventy-two patients with various hip disorders participated in this study. Of the predefined hypotheses used for construct validity, 86% were confirmed. A Cronbach alpha of 0.98 (95% CI, 0.97-0.99) demonstrated excellent internal consistency. Test-retest reliability was high, with an intraclass correlation coefficient of 0.83 (95% CI, 0.73-0.90). The standard error of measurement was 5.1 points. The smallest detectable change was 14.2 points at the individual level and 1.9 points at the group level. The minimal important change was 10.9 points. The TH-iHOT-33 had no observable floor or ceiling effects. CONCLUSION: The TH-iHOT-33 is a valid and reliable instrument for assessing the functional status and health-related quality of life of young to middle-aged physically active Thai adults with hip disorders.