Disparities in self-reported geriatric depressive symptoms due to sociodemographic differences: an extension of the bi-factor item response theory model for use in differential item functioning.

This study evaluates the measurement noninvariance, or differential item functioning (DIF), in the Center for Epidemiological Studies-Depression (CES-D) items attributable to age, sex, and race/ethnicity among community-dwelling older adults. Participants (N=2773) were from the New Haven site of the Established Populations for Epidemiologic Studies in the Elderly. Statistical analyses included exploratory factor analysis, bi-factor confirmatory factor analysis, and a bi-factor multiple indicator and multiple causes (MIMIC) model to address measurement noninvariance. Blacks, compared with whites, were more likely to endorse items loading on the interpersonal factor, which include "people dislike me" and "people are unfriendly." Women were less likely to endorse the interpersonal items and the "I felt like a failure" item (odds ratio [OR]=0.63, 95% confidence interval [CI]: 0.42, 0.94) than men. But women had a higher proportional odds than men for endorsing the "crying" item (OR=1.86, 95% CI: 1.17, 2.96). Those 75 years and older (relative to those aged 65-74) were less likely to endorse the "I felt like a failure" item (OR=0.65, 95% CI: 0.43, 0.97). However, measurement noninvariance found in both the "crying" and "failure" items were attributable to women and to those aged 75 and older were trivial after controlling for the underlying level of depressive symptomatology. Therefore, the interpersonal items showed measurement noninvariance attributable to sex and race. The bi-factor MIMIC model is useful for examining measurement noninvariance due to sociodemographics in a multidimensional depression instrument.