Translation, Cultural Adaptation and Test-retest Reliability of the German Version of the Headache Disability Questionnaire

Introduction Headaches are causing high disability. Specific questionnaires should serve as measures for headache-related disability. In German-speaking countries, there is no ideal measurement to reliably measure the severity of disability due to headache within a reasonable recall time. The Headache Disability Questionnaire (HDQ) is an English measurement that fulfills the requirements for a reliable headache questionnaire. It has not yet been translated into German.Aim To translate the HDQ into German, to adapt it cross-culturally to the German-speaking population, and to investigate its test-retest reliability.Method In a 2-phase cross-sectional study design, the HDQ was first translated into German and adapted according to the international guidelines (HDQ-G). 12 adult German native speakers participated in cognitive interviews on the comprehensibility of a pre-final German version. Subsequently, adaptations were made and documented in agreement with the author of the English version and an expert committee. Test-retest reliability of the final HDQ-G was subsequently evaluated in a sample of 29 adult headache patients using intraclass-correlation-coefficients (ICC) and visualized by a Bland-Altman plot. Participants completed an online survey with the final version twice within a period of 2 to 14 days.Results All steps of the translation process were followed and the final German version of the HDQ was completed with few additions. The HDQ-G showed very good test-retest reliability with an ICC = 0.89 (95 % confidence interval (CI) of 0.77 to 0.95). The mean difference of both surveys was + 1.72 points, with 95 % of all values within + 10.77 and -7.33 points.Conclusion The original version of the HDQ was translated and adapted for use in the adult German-speaking population in the outpatient physical therapy setting. The HDQ-G showed very good test-retest reliability and acceptable agreement for the general headache population in physiotherapy settings. Further studies are needed to investigate other scientific criteria of the HDQ.