ABSTRACT
OBJECTIVE: To develop a method for evaluating the feasibility of prenatal screening using local median value and determining the cut-off value. METHODS: With receiver operating characteristic curve (ROC) analysis, results of second trimester prenatal screening calculated by a local median value in a new model and the built-in median value in 2T software were compared. The cut-off value was set by serial analysis of true and false positive rates and other relevant data. RESULTS: The ROC curve has accurately estimated the difference in the screening efficacy between a local median value and that embedded in the 2T model, and established a reasonable cut-off value for the laboratory based on false positive rate and detection rate. CONCLUSION: The method of ROC curve can be used to evaluate the performance of local median value in prenatal screening and to test the rationality of cut-off value established in the laboratory. As the result, a better cut-off value may be derived.
