PURPOSE: To evaluate whether items of three measures of depressive symptoms function differently in persons with spinal cord injury (SCI) than in persons from a primary care sample.
METHODS: This study was a retrospective analysis of responses to the Patient Health Questionnaire depression scale, the Center for Epidemiological Studies Depression scale, and the National Institutes of Health Patient-Reported Outcomes Measurement Information System (PROMIS(®)) version 1.0 eight-item depression short form 8b (PROMIS-D). The presence of differential item function (DIF) was evaluated using ordinal logistic regression.
RESULTS: No items of any of the three target measures were flagged for DIF based on standard criteria. In a follow-up sensitivity analyses, the criterion was changed to make the analysis more sensitive to potential DIF. Scores were corrected for DIF flagged under this criterion. Minimal differences were found between the original scores and those corrected for DIF under the sensitivity criterion.
CONCLUSIONS: The three depression screening measures evaluated in this study did not perform differently in samples of individuals with SCI compared to general and community samples. Transdiagnostic symptoms did not appear to spuriously inflate depression severity estimates when administered to people with SCI.