Rescreening policies in cervical cytology and their effect on detecting the truly positive patient

In the use of a specific screening policy that relies on the expertise of cytotechnologists and pathologists to examine cytologic smears for the detection of cervical cancer, it is important to know the probability of correctly identifying a positive patient and, for each 1,000 patients, to know the probability distribution, the expected value and the standard deviation of the number of correct identifications. A probability model for the standard 10% rescreening rule mandated by the Clinical Laboratory Improvement Act of 1988 and Medicare was developed and used to evaluate higher screening rates. In addition, the model is applied to an alternative screening policy to study multiple inspections by a specific number of cytotechnologists prior to rescreening by a pathologist. For each policy the probability distribution, expected value and standard deviation of the number of correct identifications per 1,000 positive patients are given.