title: The effect of errors of diagnosis and frequency of examination on reported rates of disease.
abstract: Follow-up studies of certain diseases such as cervical dysplasia and carcinoma in situ may employ repeated screening to determine disease incidence in selected cohorts. Where errors of diagnosis occur, the true cohort experience will be distorted by an amount dependent upon the frequency of screening and the magnitude of the probabilities of incorrect diagnoses. These effects are investigated through a simple model of follow-up which employs three basic assumptions: that the probability of false positive and false negative diagnoses are constant; that individuals diagnosed as positive are treated and removed from the study, irrespective of whether or not they actually have the disease; and that fixed intervals occur between follow-up exams. The analysis permits one to assess the amount of bias introduced, and numerical examples are provided.
mesh_terms: D001699:Biometry; D003951:Diagnostic Errors; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D009017:Morbidity; D010808:Physical Examination; D013997:Time Factors