Combining direct and proxy assessments to reduce attrition bias in a longitudinal study.

TitleCombining direct and proxy assessments to reduce attrition bias in a longitudinal study.
Publication TypeJournal Article
Year of Publication2013
AuthorsWu, B, Tchetgen, EJTchetgen, Osypuk, TL, White, K, Mujahid, M, M. Glymour, M
JournalAlzheimer Dis Assoc Disord
Date Published2013 Jul-Sep
ISSN Number1546-4156
KeywordsAged, Bias, Caregivers, Dementia, Female, Humans, Longitudinal Studies, Male, Neuropsychological tests, Prevalence, Proxy

Retaining severely impaired individuals poses a major challenge in longitudinal studies of determinants of dementia or memory decline. In the Health and Retirement Study (HRS), participants complete direct memory assessments biennially until they are too impaired to complete the interview. Thereafter, proxy informants, typically spouses, assess the subject's memory and cognitive function using standardized instruments. Because there is no common scale for direct memory assessments and proxy assessments, proxy reports are often excluded from longitudinal analyses. The Aging, Demographics, and Memory Study (ADAMS) implemented full neuropsychological examinations on a subsample (n=856) of HRS participants, including respondents with direct or proxy cognitive assessments in the prior HRS core interview. Using data from the ADAMS, we developed an approach to estimating a dementia probability and a composite memory score on the basis of either proxy or direct assessments in HRS core interviews. The prediction model achieved a c-statistic of 94.3% for DSM diagnosed dementia in the ADAMS sample. We applied these scoring rules to HRS core sample respondents born 1923 or earlier (n=5483) for biennial assessments from 1995 to 2008. Compared with estimates excluding proxy respondents in the full cohort, incorporating information from proxy respondents increased estimated prevalence of dementia by 12 percentage points in 2008 (average age=89) and suggested accelerated rates of memory decline over time.


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Endnote Keywords

Dementia/Memory decline/dementia probability/composite memory score/Cognitive assessments/Proxy informants

Endnote ID


Alternate JournalAlzheimer Dis Assoc Disord
Citation Key7881
PubMed ID22992720
PubMed Central IDPMC3731387
Grant ListR21 AG034385 / AG / NIA NIH HHS / United States
U01 AG009740 / AG / NIA NIH HHS / United States
AG03438501 / AG / NIA NIH HHS / United States
U01AG009740 / AG / NIA NIH HHS / United States