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. We conclude that, using the estimates of the errors from control samples, the incidence among community subjects would be overestimated by 15%, and the incidence among the institutional subjects would be underestimated by 37%. The overall incidence would be underestimated by 14%. Most of the bias can be attributed to inaccuracies in the classification of deaths.
Hill
G
G
Canadian Study of Health and Aging, University of Ottawa, Ontario, Canada.
MacNeill
I
I
Aylesworth
R
R
McDowell
I
I
Forbes
W
W
Kozak
J
J
D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002170:Canada / Q000453:epidemiology; D002423:Cause of Death; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000706:statistics & numerical data; D003704:Dementia / Q000145:classification / Q000401:mortality*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*