Reliability and validity of the Norwegian version of the Disabilities of the Arm, Shoulder and Hand questionnaire in patients with shoulder impingement syndrome

Background: Patient-rated outcome measures (PROMs) are an important part of clinical decision-making in rehabilitation of patients with shoulder pain. The Disabilities of Arm, Shoulder and Hand (DASH) questionnaire was designed to measure physical disability and symptoms in patients with musculoskeletal disorders of the upper extremity and is one the most commonly used outcome measures for patients with shoulder pain. The purpose of this study was to investigate the reliability and validity of the Norwegian version of the DASH in patients with shoulder impingement syndrome. Methods: Sixty-three patients diagnosed with shoulder impingement syndrome at an orthopaedic outpatient clinic were included in the study. Internal consistency of the DASH was evaluated by the Cronbach's alpha and item-to-total correlations. Test-retest reliability was analyzed by the intraclass correlation coefficient (ICC) and limits of agreement (LoA) according to the Bland Altman method. Standard error of measurement (SEM) and minimally detectable change (MDC) were calculated for the total DASH score. Construct validity was evaluated by testing six a priori hypotheses for the Pearson's correlation coefficient between the DASH and the Shoulder Pain and Disability Index (SPADI), the 36-item Short Form Health Survey (SF-36) and a Numeric Pain Rating Scale (NPRS). Results: Reliability: Cronbach's alpha of the DASH was 0.93 and item-to-total correlations ranged from 0.36 to 0.81. ICC was 0.89. The 95 percent LoA was calculated to be between -11.9 and 14.1. SEM was 4.7 and MDC 13.1. Construct validity: Eighty-three percent of the a priori hypotheses of correlation were confirmed. The DASH showed a high positive correlation of 0.75 with the SPADI, a negative moderate correlation of -0.48 to -0.62 with physical functioning, bodily pain and physical component summary of the SF-36 and a moderate positive correlation of 0.58 with the NPRS. DASH correlated higher with the physical component summary than with the mental component summary of the SF-36. Conclusions: The Norwegian version of the DASH is a reliable and valid outcome measure for patients with shoulder impingement syndrome.