AN ECONOMIC-MODEL FOR COMPARING ALTERNATIVE POLICIES FOR CERVICAL CYTOLOGIC SMEAR SCREENING

In this paper a mathematical model is developed to determine the proba bility that a truly negative cervical cytologic smear will be correctl y identified by a system of screening policies that uses one or more c ytotechnologists to independently and sequentially prescreen such smea rs for the detection of cervical cancer. This is an extension of previ ous work that modeled the probability of detecting a truly positive sm ear under the same set of policies. In this system any positive readin g by a cytotechnologist causes a slide to be rescreened by a pathologi st, and if all cytotechnologists declare a slide to be negative, the s lide is placed in a pool for random selection of slides to be rescreen ed by the pathologist. The policy of single screening by a cytotechnol ogist, with subsequent 10% rescreening of the negative slides, as sugg ested by the Clinical Laboratory Improvement Amendments of 1988, is th us embedded in the policies that are modeled. In addition, a cost mode l is developed that takes into account the cost of screening a slide b y a cytotechnologist, of rescreening a slide by a pathologist, of a fa lse-positive reading and of a false-negative reading. This cost model can be used to determine which policy is optimal for the parameters th at pertain to a specific situation. Examples are presented to illustra te the use of the cost model. The results of a computer simulation mod el are also presented to validate the mathematical results and to disp lay the variability of total cost.