Is the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire adequate to assess individuals with subacromial pain syndrome? Rasch model and International Classification of Functioning, Disability and Health

Objective The Disabilities of the Arm Shoulder and Hand (DASH) questionnaire is highly used to assess patients with symptoms of subacromial pain syndrome (SPS). No study has analyzed the DASH by using the Rasch model in these patients and related the level of difficulty of the items with the International Classification of Functioning Disability and Health (ICF) domains. The purpose of this study was to evaluate the measurement properties of the DASH in individuals with SPS and to describe which International Classification of Functioning, Disability and Health (ICF) components are influenced by SPS based on the DASH. Methods The full version of the DASH was used to assess upper limbs pain and function in individuals with SPS. Responses were assessed using the Rasch model. Items of the DASH were grouped according to the level of difficulty, and associated to the ICF domains in order to identify which is the most compromised aspect in these individuals. Results Reliability and internal consistency for the DASH were shown to be 0.93 and 0.95, respectively. Item 3 (“Turn a key”) was the easiest, and 25 (“Pain during specific activity”) the most difficult. Only item 30 (“Less capable/confident/useful”) resulted as an erratic item. Item 15 (“Put on a sweater”) showed differential functioning by age, and item 11 (“Carry a heavy object”) by sex. Seven items showed differential functioning related to the angular onset of pain during arm elevation. Sixty percent of the most difficult items belonged to the “Body function” domain of the ICF. Conclusion Although some psychometric properties of the DASH are adequate according to the Rasch model, adjustments to some items are necessary for individuals with SPS. Clinicians should be cautious when interpreting the DASH, especially in patients with the angular onset of pain above 120° of arm elevation. Impact The information contained in this study should be used by clinicians to interpret the results of the DASH when assessing individuals with SPS. The DASH may not be adequate to assess those with shoulder pain above 120 degrees of arm elevation. These results are not generalizable to other shoulder pathologies.