Abstract
Background and objective
Population-based estimates of dementia can vary widely depending on the data source
and methodology used to assess cognitive impairment. The aim of this study was to
assess individual and composite measures of dementia constructed using survey and
administratively collected medical data for the purpose of improving insight into
inherent and avoidable biases and the interpretation of these measures.
Methods
A national survey of 5089 community-dwelling elderly persons was linked to 5 years
of Medicare claims. Kappa coefficients were used to assess dementia agreement between
survey, cognitive screen, and claims. Odds ratios (ORs), adjusted for age, gender,
and education, were computed to assess the relation of single- and multi-source dementia
variables to cognitive symptoms and activity limitations.
Results
Dementia prevalence among persons aged 65 and over ranged from 4.5% to 16.8% across
sources. Agreement in case identification between data sources was low, ranging from
0.15 to 0.41. Despite low agreement, ORs were consistently increased for limitations
in cognitively related activities/symptoms and non-overlapping dementia sources.
Conclusion
The finding that non-overlapping dementia data sources are associated with significantly
increased limitations in cognitive activities suggests that forecasts of national
dementia-related resource use based on single-source data could produce serious underestimates
of future need.
Keywords
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Article info
Publication history
Accepted:
April 17,
2003
Identification
Copyright
© 2003 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
