Estimating antemortem cognitive status of deceased subjects in a longitudinal study of dementia.

There was a five-year delay between the two waves of the Canadian Study of Health and Aging during which 2,982 participants died. Their cognitive status before death should be taken into account in estimating the incidence of dementia in the cohort. Information concerning antemortem cognitive status was available from death certificates and from an interview with a close relative of the decedent at the CSHA-2 follow-up.

Correlates of nonparticipation in the Canadian Study of Health and Aging.

Correlates of nonparticipation in the community interview component of the Canadian Study of Health and Aging and their impact on bias in the results were analyzed. Characteristics of study subjects, their habitats, and encouragement techniques were analyzed to identify correlates of variation in response rates across the 18 study centers. Refusal rates from 14% to 41% varied by age, gender, city size, number of subjects and length of time for enrollment, and method of approach.

Study sampling in the Canadian Study of Health and Aging.

The Canadian Study of Health and Aging drew representative samples of people aged 65 or over from the community and institutions across Canada. The sample was designed to provide regional and national prevalence estimates for dementia by age and sex. Thirty-six sampling areas were used in a stratified cluster design with optimal allocation; sampling weights were developed to provide population estimates.

Effects of screening errors and differential mortality on the estimation of the incidence of dementia in the Canadian Study of Health and Aging.

The Canadian Study of Health and Aging produced an estimate of the incidence of dementia among elderly Canadians by following up, after 5 years, the undemented found in an initial prevalence survey. Initial and follow-up estimates could be biased by false-negative error in the screening tool used for subjects living in the community, and by erroneous classification of subjects who died in the interim. Here, we use a deterministic model to quantify those possible biases.