Measuring the whole or the parts? Validity, reliability, and responsiveness of the Disabilities of the Arm, Shoulder and Hand outcome measure in different regions of the upper extremity.
The Disabilities of the Arm, Shoulder and Hand (DASH) outcome measure was developed to evaluate disability and symptoms in single or multiple disorders of the upper limb at one point or at many points in time. The purpose of this study was to evaluate the reliability, validity, and responsiveness of the DASH in a group of diverse patients and to compare the results with those obtained with joint-specific measures. Two hundred patients with either wrist/hand or shoulder problems were evaluated by use of questionnaires before treatment, and 172 (86%) were re-evaluated 12 weeks after treatment. Eighty-six patients also completed a test-retest questionnaire three to five days after the initial (baseline) evaluation. The questionnaire package included the DASH, the Brigham (carpal tunnel) questionnaire, the SPADI (Shoulder Pain and Disability Index), and other markers of pain and function. Correlations or t-tests between the DASH and the other measures were used to assess construct validity. Test-retest reliability was assessed using the intraclass correlation coefficient and other summary statistics. Responsiveness was described using standardized response means, receiver operating characteristics curves, and correlations between change in DASH score and change in scores of other measures. Standard response means were used to compare DASH responsiveness with that of the Brigham questionnaire and the SPADI in each region. The DASH was found to correlate with other measures (r > 0.69) and to discriminate well, for example, between patients who were working and those who were not (p<0.0001). Test-retest reliability (ICC = 0.96) exceeded guidelines. The responsiveness of the DASH (to self-rated or expected change) was comparable with or better than that of the joint-specific measures in the whole group and in each region. Evidence was provided of the validity, test-retest reliability, and responsiveness of the DASH. This study also demonstrated that the DASH had validity and responsiveness in both proximal and distal disorders, confirming its usefulness across the whole extremity.