Translation, cross-cultural adaptation, and psychometric properties of the german version of the hip disability and osteoarthritis outcome score.

Study Design
Clinical measurement.

Objectives
To translate and cross-culturally adapt the Hip disability and Osteoarthritis Outcome Score (HOOS) from English into German, and to study its psychometric properties in patients after hip surgery.

Background
There is no specific hip questionnaire in German that not only measures symptoms and function but also contains items about hip-related quality of life.

Methods
The translation and cross-cultural adaptation involved forward translation, harmonization, cognitive debriefing, back translation, and comparison to the original HOOS following international guidelines. The German version was tested in 51 Swiss inpatients 8 weeks after different types of hip surgery, mainly total hip replacement. The mean age of the participants was 62.5 years, and the age range was from 27 to 87 years. Thirty (58.8%) of the participants were women. Internal consistency and test-retest reliability were estimated using Cronbach alpha and intraclass correlation coefficients for agreement. For construct validity, total scores of the German HOOS were correlated with those of the Western Ontario and McMaster Universities Osteoarthritis Index. The HOOS was also compared to the Medical Outcomes Study 36-Item Short-Form Health Survey.

Results
Cronbach alpha values for all German HOOS subscales were between .87 and .93. For test-retest reliability, the intraclass correlation coefficient for agreement was 0.85 for the total scores of the German HOOS. The Spearman rho for the Medical Outcomes Study 36-Item Short-Form Health Survey physical functioning subscale compared to the sum of all HOOS subscales was 0.71, and that for the Medical Outcomes Study 36-Item Short-Form Health Survey physical component summary was 0.97.

Conclusion
The German HOOS has demonstrated adequate reliability and validity. Use of the German HOOS is recommended for assessment of patients after hip surgery, with the proviso that additional psychometric testing should be done in future research.