Differential Item Functioning of the Symptoms of Major Depression by Race and Ethnicity: An Item Response Theory Analysis

This study examines the psychometric properties, and particularly differential item functioning (DIF) due to racial and ethnic group, of the criteria for a major depressive episode using a large sample (N = 1,063) of outpatients seeking treatment for mood and anxiety disorders. DIF was evaluated using multiple group confirmatory factor analysis. Item thresholds fell along a continuum with the core features of depressed mood and anhedonia, along with fatigue, being endorsed at lower levels of depression, and change in appetite and suicidal ideation endorsed at more severe levels of depression. Item discriminations, reflecting an item’s ability to discriminate between lower and higher levels of depression, were highest for depressed mood and anhedonia, and lowest for change in appetite and suicidal ideation. When examining model fit among the racial groups we did not find differences in symptom functioning, providing support for the use of these symptoms across diverse groups. This is of particular importance given the paucity of studies examining this question using a semi-structured clinician administered instrument to a clinical sample.