DASH-ing into patient-rated outcomes

Invited commentary on: ‘Clinimetric evaluation of the disabilities of the arm, shoulder, and hand (DASH) and QuickDASH questionnaires for patients with shoulder disorders’, Kolber MJ et al. This manuscript 1 is a high-quality systematic review examining the clinimetric properties of the Disability of the Arm, Shoulder, and Hand (DASH) and its abbreviated form (QuickDASH). Across 18 articles, these widely referenced patient-rated assessments consistently demonstrated high levels of performance (e.g. reliability, validity, responsiveness). I commend the authors for writing a clear manuscript that explicitly defined the test characteristic being analysed. I expect the ease of reading this work will broaden the appeal and utilization of this manuscript as a referenced work. This work confirmed the strong performance traits of each survey. Reliability was exceptional with intraclass correlation coefficients above 0.90. Each instrument was highly internally consistent. Based on variance of data, minimal detectable change estimates were clustered near 11 points. Construct validity was confirmed by positive correlations with alternative measures of patient function. These correlations were imperfect, suggesting that DASH and QuickDASH are measuring comparable, but not identical, aspects of function when compared to other validated tests. Finally, these surveys have been shown to be reasonably responsive to change in health states and have limited floor and ceiling effects. This review, and all other systematic reviews, has limitations both secondary to methodology and as a function of the available literature. Although titled as a work on shoulder disorders, the authors of this work chose to analyse articles including patients with shoulder as well as other upper extremity conditions. In the end, this may improve the ability to generalize conclusions reached to the upper extremity disorders more broadly. Meanwhile, the authors restricted analysis to articles primarily focused on the test characteristics of the DASH and QuickDASH. While a reasonable restriction, broader inclusion criteria such that any article reporting a clinimetric property of either survey would have been included even if this was not the stated purpose of the article may have added to the breadth of data collected. When considering use of the DASH and QuickDASH for a preponderance of upper extremity conditions I would expect them to perform well as the data in this review indicate. However, investigators must still critically evaluate how these surveys will behave in any given study cohort. First, the performance of these measures will depend on the population of interest. 2 Even if studying shoulder disorders, a group of patients treated for brachial plexus injury may have such limited function that the floor effects become relevant. Alternatively, in a group of professional baseball pitchers with shoulder pain in their dominant arms, treatment may substantially improve their performance despite universally perfect scores on both pre- and post-testing with the relatively basic tasks queried by the DASH (i.e. ceiling effect). Second, the desirable instrument properties found when researching groups of patients is not maintained in very small groups. 3 On an