Construct validity and reliability of the disability of arm, shoulder and hand questionnaire for upper extremity complaints in rheumatoid arthritis

Abstract

Objective. The Disability of Arm, Shoulder and Hand (DASH) questionnaire is a tool for measuring physical function and symptoms of the upper extremity. Although widely used, it is not validated for rheumatoid arthritis (RA). In this study the DASH was validated for this patient group. Methods. In total, 102 patients participated in this study. For the validation, the questionnaires of the DASH, the Health Assessment Questionnaire (HAQ), the Medical Outcomes Study Short Form-36 (SF-36), and the Arthritis Impact Measurement Scale (AIMS2) were used. Patients were examined clinically before completing the questionnaires. Pain was scored by each patient using a visual analog scale (VAS). The Disease Activity Score (DAS28) was obtained and grip strength was measured. Reliability was tested by a second DASH questionnaire after 2 days. Validity was tested using a Pearson correlation analysis for the relevant domains of the questionnaires and for the clinical aspects. Results. The reliability of the DASH was excellent (intraclass correlation coefficient 0.97). Internal consistency was strong (Cronbach's alpha 0.97). Validity was proven with excellent results for Pearson correlation with the relevant domains of the questionnaires: HAQ, r = 0.88; SF-36, r = 0.70; and AIMS2, r = 0.85. The clinical scores had a relatively low correlation with the DASH (DAS28, r = 0.42; and grip strength, r = 0.41-0.48), except for the VAS (r = 0.60-0.65). Conclusion. The DASH is a reliable and valid questionnaire in patients with RA. It can be used as a measurement tool of physical disability of the upper extremity.