Objective: In 1994 the American Academy of Orthopedic Surgeons' outcome research committee developed and validated a functional outcome questionnaire for disabilities of the upper extremity (DASH). The objective of our study was to translate the DASH into German and to evaluate its reliability and validity for German-speaking patients with shoulder pain.
Methods: Translation-backtranslation of the DASH was performed according to published guidelines. Psychometric properties and validity were assessed in 49 consecutive patients with shoulder pain originating from within the shoulder girdle. Age, duration of symptoms and current pain were obtained. Test-retest reliability was assessed in a subset of 18 patients who filled in the questionnaire 10 days later. Internal consistency was evaluated with Cronbach's alpha coefficient. Test-retest reliability was assessed using Spearman correlations and the Bland and Altman plot. To study the validity, we examined the correlation of the DASH with other measures of function of the upper extremity including the HAQ subscales relating to the upper extremity and pain measures (e.g. numerical rating scale, SF-36 pain scale). We also examined our hypothesis that the DASH is moderately correlated with measures of range-of-motion (e.g., forward flexion and abduction).
Result: Translation-backtranslation revealed no major difficulties. The mean age of the patients was 59 years, mean duration of symptoms 60 months and current pain score 5.6 (NRS). Test-retest reliability was 0.90 for the total DASH. The internal consistency was 0.96. Strong correlations (p<0.01) were found between the DASH and the mean among the five subscales of the HAQ representing upper extremity function (0.88) and pain as measured with the SF-36 bodily pain scale (-0.79). As hypothesized, the DASH was also moderately correlated with measures of range-of-motion (e.g. forward flexion rho=-0.49; abduction rho=-0.57).
Conclusion: Our data confirm that the German version of the DASH retains the characteristics of the American original and is a reliable and valid instrument to measure functional disability in German speaking patients with shoulder pain.