Improving outcomes for Colorado's IRT-IRT-DNA cystic fibrosis newborn screening algorithm by implementing floating cutoffs

The Colorado Newborn Screening Program (CO-NBS) screens for cystic fibrosis (CF) by measuring immunoreactive trypsinogen (IRT) from two screens coupled with DNA analysis (IRT/IRT/DNA). The Colorado CF Care Center identified 8 missed CF cases among 358,187 infants screened by the CO-NSP since 2016. Retrospective analysis of CO-NSP IRT data shows that a 96th percentile floating IRT cutoff with a 50 ng/mL fixed cutoff on the first screen, and second screen 50 ng/mL fixed cutoff would have identified 7 of the 8 missed cases. These efforts demonstrate the importance of continuous quality improvement in order to increase sensitivity and reduce missed cases.