Recall Rate in Congenital Hypothyroidism Screening: Influence of the Day of Sample Collection and Lower Cutoff.

Abstract

The recall rate in congenital hypothyroidism (CH) newborn screening programs depends on several factors such as primary screening strategy, sample collection guidelines, and cut-off. A recall rate of 0.05% is recommended but recall rates of 0.01-13% are reported worldwide. The aim of the study was to assess the recall rate in association with the age of the newborn at sample collection and with a lower cut-off. This was a retrospective correlational study concerning TSH results in CH screening program. All newborns from a tertiary center in Targu Mures, Romania between 2013-2018 were included. Four groups were created and a correlation test between TSH median value and age in days was performed. The recall rate was calculated using three cut-off levels for 8182 TSH results performed in 2018. 90% of the DBS were collected in days 3-5 after birth and 1/79 live births from this group had TSH above the lower cut-off used (10 mUI/L). 2% of the samples were collected in less than 48 hours after birth and 1/21 live birth from this group had TSH > 10 mUI/L. The recall rate in our center in 2018 was 0.08%, higher than the recommended rate of 0.05%. With the cut-off value recommended by the Health Ministry a 0.03% recall rate was obtained. Sample collection in less than 48 hours increases the recall rate in CH screening with TSH primary testing strategy. A lower cut-off raises the recall rate with a higher rate of false-positive cases (94.12%) but with 100% negative predictive value.