The international Hip Outcome Tool-33 (iHOT-33): multicenter validation and translation to Spanish

Background: The international Hip Outcome Tool-33 (iHOT-33) is a 33-item self administered outcome measure based on a Visual Analogue Scale response format designed for young and active population with hip pathology. The aim of the present study is to translate and validate the iHOT-33 into Spanish. Methods: 97 patients undergoing hip arthroscopy were included in this prospective and multicenter study performed between January 2012 and May 2014. Crosscultural adaptation was used to translate iHOT-33 into Spanish. Patients completed the questionnaire before and after surgery. Feasibility, reliability, internal consistency, construct validity (correlation with Western Ontario and McMaster Universities Osteoarthritis Index), ceiling and floor effects and sensitivity to change were assessed for the present study. Results: Mean age was 48 years old. Feasibility: 41.2 % patients had no blank questions, and 71.3 % of patients had fulfilled all but one or two questions. Reliability: ICC for the global questionnaire was 0.97, showing that the questionnaire is highly reproducible. Internal consistency: Cronbach's alpha was 0.98 for the global questionnaire. Construct validity: there was a high correlation with WOMAC (correlation coefficient >0.5). The Ceiling effect (taking into account the minimum detectable change) was 12.1 % and the floor effect was 21.6 %, for the global questionnaire. Large sensitivity to change was shown. Conclusion: the Spanish version of iHOT-33 has shown to be feasible, reliable and sensible to changes for patients undergoing hip arthroscopy. This validated translation of iHOT-33 allows for comparisons between studies involving either Spanish-or English-speaking patients.