Measuring depression among persons with stroke faces many challenges; diagnostic tools are lengthy and do not measure the extent of depression; screening tools are not stroke-specific; and metrics from the available indices do not provide a value that is mathematically or clinically meaningful. Purpose: To provide evidence for the development of a stroke specific Geriatric Depression Scale screening measure (SS-GDS) through Rasch methodology. Methods: Secondary analyses of a randomized controlled trial post-stroke. Interviews from 91 subjects aged 71 (SD 10) over three time points or 240 interviews were analyzed. Rasch Analysis helped transform the 30-item GDS onto a logit scale. Unidimensionality, item fit, redundancy, and differential item functioning (DIF) were assessed. Results: Seventeen items fit the model to form a hierarchical measure ranging in difficulty from ΓΎ1.2 to Γ1.8 logits. Preliminary psychometric properties of reliability, validity, and responsiveness were adequate. Two items that demonstrated DIF, one for language and one for gender, were split.
Conclusion:
The 17-item SS-GDS Rasch measure was developed to screen for post-stroke depression (PSD) and provide an important step toward quantifying PSD. If revalidated in a larger sample, the SS-GDS could provide a mathematically valid index to screen for depression in stroke survivors. Copyright