Structural validity of the Arabic version of the disabilities of the Arm, Shoulder and Hand (DASH) using Rasch measurement model

Abstract

Background The disabilities of the arm, shoulder and hand (DASH) is a commonly used region-specific patient-reported outcome measure (PROM) that quantify upper extremity function (activity limitation) and symptoms. Current evidence suggests that measurement properties of the adapted versions of the DASH are not sufficiently examined. The Arabic DASH has evidence supporting its internal consistency, test–retest reliability, construct validity and responsiveness. On the other hand, the validity of the assumed unidimensionality of the Arabic DASH has not been examined previously. The aim of this study was to examine the structural validity of the Arabic DASH in patients with upper extremity musculoskeletal disorders using Rasch measurement model. Methods Patients with upper extremity musculoskeletal disorders were recruited and were asked to complete the Arabic DASH at their initial visit to physical therapy departments. The overall fit of the Arabic DASH to the requirement of the Rasch measurement model was examined using chi-square statistics for item-trait interaction, mean item and person fit residuals. The fit of individual items, thresholds ordering, local dependency, differential item functioning (DIF), and unidimensionality using the t-test approach were also examined. Results The Arabic DASH did not fit the Rasch measurement model initially (χ2 = 179.04, p < 0.001) with major breach of local item independence and a pattern of high residual correlations among the activity-related items and among the impairment-related items. Combining items into activity-limitation and impairment testlets accommodated the local dependency and led to satisfactory fit of the Arabic DASH to the requirement of the Rasch measurement model (χ2 = 3.99, p = 0.41). Conclusions Rasch measurement model supports the structural validity of the Arabic DASH as a unidimensional measure after the accommodation of local dependency.

Assessment of structural and cross-cultural validity of the Disabilities of the Arm, Shoulder and Hand questionnaire: a scoping review

“…There are 17 language versions with evidence of the assessment of structural validity of which the following language versions had evidence of EFA: Chinese, 33 French, 34 German, 35 Igbo, 36 Japanese, 37 Nepali 38 Persian, 39 Portuguese (Brazil), 40 Taiwanese 41 and Yoruba. 42 The Arabic, 43 Dutch, 44 English (British) 45,46 and Finish 47 language versions have evidence of structural validity through Rasch analysis. In a separate study from authors from the Netherlands, CFA was conducted using the Dutch DASH questionnaire.…”

“…Of the studies that investigated the factor structure of the DASH questionnaire, eight studies concluded that the questionnaire holds a single factor structure. 33,37,39,41,43,44,46,48 One study supported a two factor structure, 36 five a three factor structure, 35,40,[49][50][51] one a four factor structure, 38 one a five factor structure 34 and one a seven factor structure. 42…”

Structural and cross-cultural validity of the Afrikaans for the Western Cape Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire

“…The decision to conduct CFA towards confirming a one-factor structure in the Afrikaans for the Western Cape DASH follows best practice in accordance with the COSMIN guidelines [ 25 , 34 ], and in line with previous evidence supporting the unidimensionality of this instrument [ 17 – 23 , 35 , 36 ]. Several studies on the structural validity of the DASH questionnaire following translation and cross-cultural adaptation however did not support unidimensionality [ 37 – 46 ].…”

“…Factor analysis of the Nigerian Igbo version of the DASH questionnaire also revealed a two-factor structure [ 42 ]. This study from Nigeria is one of few (excluding the current study) reporting on language versions from the African continent and to our knowledge the only to report a two-factor model [ 17 , 41 , 42 , 48 , 49 ]. Our findings were similar to that of Ibikunle et al (Igbo DASH) with their Factor 1 (strength based) also comprising of items 1–21 explaining 58.5% of the variance and Factor 2 (pain based) items 22–30 explaining 6.8% of the variance [ 42 ].…”

“…This is done through either confirmatory or exploratory factor analysis. confirmatory factor analysis (CFA) is preferred when there is existing evidence or a previous hypothesis about the number of factors that exist for the measure [16][17][18][19][20][21][22][23]. CFA was utilised in the present study to evaluate a one-factor structure in the Afrikaans for the Western Cape DASH questionnaire.…”