A non-inferiority test and sample size determination for comparing two predictive values of diagnostic tests.

Positive and negative predictive values describe the clinical performance of the diagnostic test when it is applied to a cohort of individuals. Testing non-inferiority of predictive values may be adequate in some cases due to the simplicity of the examination and the invasiveness of the test, but no non-inferiority test for predictive values has been proposed yet. In this study, we propose a non-inferiority test that investigates the non-inferiority of predictive values in paired designs, and formulae for the calculation of sample size to execute the non-inferiority test of two predictive values. Simulation studies showed that the proposed non-inferiority test is useful for comparing two predictive values in clinical trials. [ABSTRACT FROM AUTHOR]