Establishment of Cutoff Value in the Neonatal Screening Tests

Kim, You Jeong; Kim, Ja Hyung; Cheon, Sa Il; Min, Won Ki; Shin, Young Lim; Yoo, Han Wook

Abstract

PURPOSE: This study was undertaken to determine the adequate cutoff value of the neonatal screening test to decrease recall and false-positive rates.
METHODS
During the period of January 1999 through December in Asan Medical Center, newborn screening tests for phenylketonuria, congenital hypothyroidism, congenital adrenal hyperplasia, and galactosemia were performed in 3,775, 3,707, 3,783, and 3,806 newborns respectively using commercial ELISA kits. We reviewed and analyzed the recall rate at currently used cutoff values.
RESULTS
1)In neonatal screening test for congenital hypothyroidism, using a current cutoff value, 17 microIU/mL, the recall rate was 0.9% and using a 99.7% cutoff value, 21.3 microIU/mL, the predictive recall rate was 0.4%. There were no significant differences in the other reports that suggest adequate recall rate. 2)In neonatal screening test for phenylketonuria, using a current cutoff value, 3.6 mg/dL, the recall rate was 1.5% which was no significant difference compared with expected presumptive positive rate, 1.44%. 3)In neonatal screening test for congenital adrenal hyperplasia and galactosemia, the recall rate was high when using current cutoff value. But all results were within normal limits in reevaluation.
CONCLUSION
The cutoff values of screening test which are currently recommended by manufacturers of commercial kits for congenital hypothyroidism, congenital adrenal hyperplasia and galactosemia, are needed to be reset to decrease the recall rate by false-positive results on the basis of data from an individual newborn screening laboratory.