Evaluating screening tests for dementia and cognitive impairment in a heterogeneous population in the presence of verification bias.
This article reviews two potentially serious sources of error in the evaluation of screening tests, namely, verification bias and the influence of demographic covariates. It demonstrates how to deal with these problems statistically. Verification bias arises when not all subjects receive a definitive diagnosis following a screening test. If only a small proportion of those who screen negative are sent for diagnosis, the calculated test sensitivity is an overestimate and the calculated specificity an underestimate. The methodology outlined in this article may be extended to psychological and medical screening tests in general.
Donald
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Donald Associates, Vancouver, British Columbia, Canada.
Van Til
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D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002170:Canada / Q000453:epidemiology; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000706:statistics & numerical data; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics; D015203:Reproducibility of Results