The Unified Dyskinesia Rating Scale items effectively capture dyskinesia severity without pertinent gender, age, race/ethnicity, or education influence, according to a recent study. Using Unified Dyskinesia Rating Scale translation databases (n=3,132), researchers tested uniform and nonuniform differential item functioning. They required confirmation by 2 independent methods and considered differential item functioning pertinent if McFadden pseudo R² magnitude statistics exceeded negligible ratings. They found:

• No age, race/ethnicity, or education nonuniform differential item functioning was identified.
• Gender nonuniform differential item functioning occurred for 2 items, both with negligible magnitude.
• Gender, race, and education uniform differential item functioning was observed for multiple items, all with negligible magnitude.