Fundamental Considerations on the Health-Checkup Accuracy of Multiple Tests

Abstract

For finding the optimum combination of multiple tests in the multiphasic health-checkup system, it was considered how the healthcheckup accuracy changes with the number of tests (n) and five kinds of combination methods: A) Sequential tests, B) Sequential tests after changing the order in A, C) Simultaneous tests using the Believe-the-Negative Rule, D) Simultaneous tests using the Believe-the-Positive Rule, and E) Simultaneous tests using the Believe-all-Positive-all-Negative Rule. The health-checkup accuracy is defined by sensitivity (α) and specificity (β) . An over-all two-by-two table for multiple tests was inducted from the two-by-two tables for each test. An over-all health-checkup accuracy was calculated from the over-all two-by-two table, and was expressed by a generalized formula. As it was proved that combination methods A, B and C are“equivalent”for the accuracy, the five methods could be summarized into three kinds of methods. As results, for A, B and C: R increased but a decreased with increasing n. For D: a increased but R decreased with n. For E: Both a and R increased with n, although problem exists concerning how to judge the remaining subjects who are between positive in all tests and negative in all tests. In order solve this problem, “the case grading and categorization method”are proposed. Six kinds of unified index of diagnostic accuracy are comparatively discussed.