Analysis of agreement between measures of subjective cognitive impairment and probable dementia in the National Health and Aging Trends Study

Abstract

Background: Subjective cognitive impairment (SCI) measures in population-based surveys offer potential for dementia surveillance, yet their validation against established dementia measures is lacking.

Methods: We assessed agreement between SCI and a validated probable dementia algorithm in a random one-third sample (n = 1936) of participants in the 2012 National Health and Aging Trends Study (NHATS).

Results: SCI was more prevalent than probable dementia (12.2% vs 8.4%). Agreement between measures was 90.0% and of substantial strength. Misclassification rates were higher among older and less-educated subgroups due to higher prevalence of false-positive misclassification but did not vary by sex or race and ethnicity.

Discussion: SCI sensitivity (63.4%) and specificity (92.5%) against dementia were comparable with similar metrics for the NHATS probable dementia measure against the "gold-standard" Aging, Demographics, and Memory Study-based dementia criteria, implying that population-based surveys may afford cost-effective opportunities for dementia surveillance to assess risk and inform policy.

Highlights: The prevalence of subjective cognitive impairment (SCI) is generally higher than that of a validated measure of probable dementia, particularly within the youngest age group, females, Whites, and persons with a college or higher degree. Percent agreement between SCI and a validated measure of probable dementia was 90.0% and of substantial strength (prevalence- and bias-adjusted kappa, 0.80). Agreement rates were higher in older and less-educated subgroups, driven by the higher prevalence of false-positive disagreement, but did not vary significantly by sex or race and ethnicity. SCI's overall sensitivity and specificity were 63.4% and 92.5%, respectively, against a validated measure of probable dementia, suggesting utility as a low-cost option for dementia surveillance. Heterogeneity in agreement quality across subpopulations warrants caution in its use for subgroup analyses.

Keywords: ADRD; Alzheimer's disease; NHATS; dementia; disability questionnaire; subjective cognitive impairment.