Reliability, validity and responsiveness of the Kurdish version of the questionnaire Disability of the Arm, Shoulder and Hand in patients with carpal tunnel syndrome

INTRODUCTION: The Disabilities of Arm, Shoulder and Hand (DASH) questionnaire predicts the amount of the patient's inabilities and symptoms to evaluate the impacts of upper limb conditions in the patient's daily-life activities. This study aims to test the psychometric properties of DASH in Kurdish patients with carpal tunnel syndrome.

MATERIALS AND METHODS: 93 patients with diagnosed carpal tunnel syndrome subjected to complete the self-report DASH-KU and patient rated wrist\hand evaluation PRWHEKU questionnaire during two consecutive assessments with a 24-hour interval before any intervention.

RESULTS: DASH-KU questionnaire had excellent internal consistency (Cronbach's alpha = 0.99) and test-retest reliability (intra-class correlation coefficient =0.99). A strong correlation between the DASH-KU score and the PRWHE tool (r=0.792) demonstrated acceptable construct validity of DASH-KU. Bland-Altman plot showed good agreement between the two assessments of DASH-KU, and no floor (3%) nor ceiling effects (0%) were observed. Factor analysis showed that the DASH-KU scale had a high acceptable adequacy (adequacy index = 0.700) and a significant sphericity (p<0.001). The analysis showed a major factor that accounted for 40% of the observed variance with an eigenvalue of 13.14. In addition, five items model also explained 81.23% of the DASH-KU scale variance. However, the responsiveness of DASH-KU was suboptimum, which can be linked to the short 24-hour interval between measurements.

CONCLUSION: The DASH-KU scale is a reliable, valid, and responsive instrument for assessing disabilities in patients with carpal tunnel syndrome.