Damaged goods?: an empirical cohort study of blood specimens collected 12 to 23 hours after birth in newborn screening in California

Purpose: The current Clinical and Laboratory Standards Institute standard recommends blood collection from 24 to 48 hours after birth for newborn genetic disorder screening. We used California population-level data to determine whether early specimens (collected from 12 to 23 hours) would also be considered satisfactory based on screening performance. Methods: Screening data from California Genetic Disease Screening Program were analyzed for false-negative and false-positive rates in four disease categories: metabolic disorders detectable by tandem mass spectrometry (MS/MS); congenital adrenal hyperplasia (CAH); congenital hypothyroidism (CH); and initial immune reactive trypsinogen (IRT) for cystic fibrosis (CF). We compared the rates between the early-collection group (12 to 23 hours) and the standard-collection group (24 to 48 hours). Results: No significant difference of false-negative rate was detected between the two collection-timing groups. Early specimens had a significantly higher false-positive rate for CH (0.10 vs. 0.01%) and IRT (1.85 vs. 1.54%) but a lower false-positive rate for MSMS metabolic disorders (0.11 vs. 0.18%) and CAH (0.10 vs. 0.14%). Conclusion: Newborn specimens collected after 12 hours provided satisfactory screening performance. A policy allowing earlier collection could improve timeliness of reporting screening results. Genet Med 18 3, 259–264.