Is DASH Still Reliable for Nerve Transfer?
By Kazuteru Doi, MD, PhD
The Disability of the Arm, Shoulder And Hand (DASH) Outcome Measure is the most-widely used patients’ reported outcomes in the world. It comprises of 30 items, of which 21 relate to function, 6 to pain, and 3 self-impact items.
The DASH has been used as a Quality of Life (QoL) assessment in most studies on nerve transfer outcomes in brachial plexus injuries, including my publications. The exceptions are Mancuso and Novak. However, DASH scores may misrepresent patients’ QoL.
The current DASH has three flaws which make outcomes analysis inaccurate. Firstly, DASH gives equal weightage to each item in the different components. In most previous articles, only the final DASH scores were compared. They failed to compare individual component scores. Although patients may have the same total disability score, the component scores can differ, producing misinterpretations in true QoL outcomes.
Next, each of the 30 items has a varying degree of difficulty, which can also be a source for data misinterpretation. When the Rasch model was applied to average this discrepancy of item difficulty, 30 items of original DASH were converted to the interval scale, and 12 misfit items with larger residuals were removed. The remaining DASH 18 items were used for outcomes analysis.
The DASH-18, still included questions relating to function, pain and impact. We analyzed the DASH-18 on our patients and found no significant difference in post-operative and improvement scores comparing C56 (567), C5-8 and total palsies, despite their functional differences like range of joint motion and power of elbow flexion.
The third problem with DASH is it reflects the degree of compensation by the contralateral normal hand or unique lifestyle adaptations to perform these items. The DASH does not directly evaluate the function recovered in the affected limb. Instead, the responses are based on the ability to perform the task irrespective of the limb used and the patient’s ability to adapt (Hill BE, 2016).
As a consequence, we should recognize that DASH scores do not measure recovery of an injured limb after nerve transfers, but instead reports goodness of fit to the items. It has shortcomings as it measures compensatory strategies employed by the patient over time, and is not a marker of improvement in use of the affected limb.
Kazuteru Doi, MD, PhD
General President, Ogori Daiichi General Hospital
Department of Orthopedic Surgery
Ogori, Shimoto 862-3, Yamaguchi, Japan
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