title: Differential item functioning due to cognitive status does not impact depressive symptom measures in four heterogeneous samples of older adults.
abstract: 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.
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Fieo
authors.affiliation: General Internal Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Shubhabrata
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA.
authors.forename: Natalia O
authors.initials: NO
authors.lastname: Dmitrieva
authors.affiliation: Kessler Foundation, Spinal Cord Injury/Outcomes and Assessment Laboratory and New Jersey Medical School, Rutgers University, West Orange, NJ, USA.
authors.forename: Denise C
authors.initials: DC
authors.lastname: Fyffe
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.|Center on Aging and Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Alden L
authors.initials: AL
authors.lastname: Gross
authors.affiliation: General Internal Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Sanders
authors.affiliation: Joseph and Kathleen Bryan Alzheimer's Disease Research Center, Duke University Medical Center, Durham, NC, USA.|Department of Psychology, University of Notre Dame, Notre Dame, IN, USA.
authors.forename: Heather R
authors.identifier: http://orcid.org/0000-0001-7558-3720
authors.initials: HR
authors.lastname: Romero
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA.|Joseph and Kathleen Bryan Alzheimer's Disease Research Center, Duke University Medical Center, Durham, NC, USA.
authors.forename: Guy G
authors.initials: GG
authors.lastname: Potter
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Manly
authors.affiliation: Department of Neurology, University of California, Davis Medical Center, Sacramento, CA, USA.
authors.forename: Dan M
authors.initials: DM
authors.lastname: Mungas
authors.affiliation: General Internal Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Gibbons
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000523:psychology*; D003866:Depressive Disorder / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales
keywords: cognitive impairment; depressive symptoms; differential item function; item bias