Psychometric evaluation of the World Health Organization Disability Assessment Schedule 2.0 for Mild Traumatic Brain Injury using Rasch Analysis
Bibliographic record
Abstract
Background and Objectives:The World Health Organisation Disability Assessment Schedule 12-item version (WHODAS-2.0) is a measure of disability representing six International Classification of Disability, Functioning, and Health activity and participation domains, including cognition, mobility, self-care, interpersonal functioning, life activities, and participation. Preliminary validation analyses of the WHODAS-2.0 as an outcome measure for mild traumatic brain injury (MTBI) using classical test theory methods, were promising. The objective of this study was to further examine the psychometric properties of the WHODAS-2.0 for MTBI by applying Rasch Analysis, specifically considering unidimensionality and responsiveness to injury recovery.Method:Adults (n = 148) who were recruited from outpatient clinics in Vancouver following MTBI completed the WHODAS-2.0 at on average 10 weeks and then again 20 weeks following injury. We used Rasch analysis to determine overall and individual item fit to the Rasch model at each time point, differential item functioning (DIF), local independence, unidimensionality and person-separation reliability of the WHODAS 2.0 using RUMM2030 software. Paired t-tests were used to evaluate change in scores with time.Results:Participants were on average 40 years old (SD 12.1), predominantly Caucasian (66%), with slightly more women (66%) than men in the sample. The most common injury mechanism was motor vehicle accident (48%). Best fit to the unidimensional Rasch model at time one was achieved after locally dependent items were combined into three subtests or super-items (Chi square = 3.63, df 6, p = 0.73). The modified WHODAS-2.0 demonstrated high internal consistency (Person Separation Index (PSI) = 0.91) and there was no DIF across person factors examined. Time 2 analyses although exploratory, due to a small (n=80) sample, were also suggestive of good fit to the Rasch model and high internal consistency (Chi square = 22.21, df 22, p = 0.45; PSI = 0.90). The results support retaining the original response format and content of the measure. From these analyses we created ordinal-to-interval conversion tables that will allow more precise assessment of MTBI outcome across individuals on an interval scale. Finally changes in WHODAS-2.0 total raw scores between times one and two were significant (mean difference = 5.59; 95% confidence interval 4.05, 7.14; p<0.01), and person-item threshold distributions from Rasch analysis reflected reducing disability with time in this sample.Conclusions:With minor modifications, the WHODAS-2.0 demonstrated adequate properties as a unidimensional scale and showed responsiveness to improvement with time and MTBI recovery. Rasch analyses supported the WHODAS-2.0 as a psychometrically sound measure of outcome in adults after MTBI.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.017 | 0.052 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.003 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; both teacher heads agree on what is shown here.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".