Evaluating Differential Item Functioning of the PRIME-MD Mood Module Among Impoverished Black and White Women in Primary Care

BACKGROUND: Appropriate treatment of depression requires accurate screening and diagnosis. It is important to evaluate depression screening instruments for differential item functioning (DIF) across diverse populations. The PRIME-MD is commonly used in primary care settings to screen for the most common psychiatric disorders, including depression. The purpose of this study was to determine whether items in the mood module of the PRIME-MD perform similarly in 2 high-risk populations: impoverished black and white women. METHODS: Data were collected during screening for a randomized controlled trial of treatment for depression in women receiving county health and welfare services. Analyses are based on a sample of 3,506 black (n = 3,191) and white (n = 315) women who completed the PRIME-MD mood module. Responses were compared using an item response theory approach to DIF assessment. Mean scores, missing data, and internal consistency reliability were also compared. RESULTS: None of the 9 items exhibited significant DIF. Missing data rates and internal consistency reliability did not differ for the 2 groups. Mean comparisons indicated that white women endorsed higher levels of depression compared with black women on 6 of the 9 items (p < .05). CONCLUSIONS: These results suggest that all items of the mood module of the PRIME-MD performed similarly for white and black women. Differences in endorsed depressive symptomatology on the mood module may be attributed to actual differences in DSM-IV depression symptoms between white and black women.