Accounting for lack of representation in dementia research: Generalizing KHANDLE study findings on the prevalence of cognitive impairment to the California older population.

Abstract

Most dementia studies are not population-representative; statistical tools can be applied to samples to obtain critically-needed population-representative estimates, but are not yet widely used. We pooled data from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) study and the California Behavioral Risk Factor Surveillance System (CA-BRFSS), a population-representative study. Using weights accounting for sociodemographic/health differences between KHANDLE and CA-BRFSS, we estimated cognitive impairment prevalence and age- and sex-adjusted racial/ethnic inequalities in California adults 65+ without prior dementia diagnosis. After weighting KHANDLE, the estimated cognitive impairment prevalence in California was 20.3% (95% confidence interval 17.8-23.0); unweighted prevalence was 24.8% (23.1%-26.6%). Inequalities (larger prevalences) were observed among Black and Asian groups versus whites. We used a novel statistical approach to estimate population-representative cognitive impairment prevalence and inequalities. Such statistical tools can help obtain population-representative estimates from existing studies and inform efforts to reduce racial/ethnic disparities.