Differential item functioning due to cognitive status does not impact depressive symptom measures in four heterogeneous samples of older adults

• Published in: International journal of geriatric psychiatry Vol. 30; no. 9; pp. 911 - 918
• Main Authors: Fieo, Robert, Mukherjee, Shubhabrata, Dmitrieva, Natalia O., Fyffe, Denise C., Gross, Alden L., Sanders, Elizabeth R., Romero, Heather R., Potter, Guy G., Manly, Jennifer J., Mungas, Dan M., Gibbons, Laura E.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.09.2015; Wiley Subscription Services, Inc
• Subjects: Aged; Aged, 80 and over; Aging; Cognition - physiology; Cognition Disorders - psychology; Cognitive ability; cognitive impairment; Depressive Disorder - diagnosis; Depressive Disorder - physiopathology; depressive symptoms; differential item function; Female; Geriatric psychiatry; Humans; item bias; Longitudinal Studies; Male; Mental depression; Middle Aged; Older people; Psychiatric Status Rating Scales; United States > US; cognitive impairment; differential item function; depressive symptoms; item bias
• ISSN: 0885-6230; 1099-1166
• DOI: 10.1002/gps.4234

Objective The objective of this study is to determine whether differential item functioning (DIF) due to cognitive status impacted three depressive symptoms measures commonly used with older adults. Methods Differential item functioning in depressive symptoms was assessed among participants (N = 3558) taking part in four longitudinal studies of cognitive aging, using the Geriatric Depression Scale, the Montgomery–Åsberg Depression Rating Scale, and the Center for Epidemiologic Studies Depression Scale. Participants were grouped by cognitive status using a general cognitive performance score derived from each study's neuropsychological battery and linked to a national average using a population‐based survey representative of the US population. The Clinical Dementia Rating score was used as an alternate grouping variable in three of the studies. Results Although statistically significant DIF based on cognitive status was found for some depressive symptom items (e.g., items related to memory complaints, appetite loss, lack of energy, and mood), the effect of item bias on the total score for each scale was negligible. Conclusions The depressive symptoms scales in these four studies measured depression in the same way, regardless of cognitive status. This may reduce concerns about using these depression measures in cognitive aging research, as relationships between depression and cognitive decline are unlikely to have been due to item bias, at least in the ways that were measured in the datasets we considered. Copyright © 2014 John Wiley & Sons, Ltd.