Evaluating Differential Item Functioning in EQ-5D-5L in Acute Ischemic Stroke: Evidence From the ACT Trial.
StrokeJul 23, 2026 (epub)
Olayinka I Arimoro, Ayoola Ademola, Michael D Hill et al.
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In 30 seconds
This randomized controlled trial evaluated differential item functioning (DIF) in the EQ-5D-5L questionnaire among 1264 patients with acute ischemic stroke. The study found significant DIF related to age, particularly in self-care and usual activities, with moderate effect sizes of -0.46 and -0.34, respectively. No DIF was detected for sex or treatment groups.
Key findings
- Significant DIF was found for age (χ 2 =86.9, P <0.001) but not for sex or treatment.
- Moderate effects were noted for self-care (sWABC=-0.46) and usual activities (sWABC=-0.34).
- Pain/discomfort and anxiety/depression showed negligible DIF (sWABC=-0.002 and sWABC=0.09, respectively).
- Factor scores with and without DIF adjustment had a high correlation (0.98).
Why it matters
Understanding DIF in health-related quality of life measures is crucial for accurate treatment comparisons in stroke trials. This study supports the EQ-5D-5L's reliability across different demographic groups, enhancing its utility in clinical research.