[Comparison of diagnostic data after introduction of cystic fibrosis screening in newborns in Germany].

backgroundIn Germany, newborn screening (NGS) for cystic fibrosis (CF) was introduced on 1 September 2016. There is no legally required follow-up of abnormal screening findings, so the exact number of final diagnoses is not known. Two data sources can support the evaluation of the cystic fibrosis screening: the German Society for Newborn Screening (DGNS) collects the results of NGS and confirmatory testing for quality assurance and the German Cystic Fibrosis Registry (DMR) collects diagnostic frequencies. The aim of this manuscript is to compare the data from the DGNS and the DMR and to present limitations and strengths of each data source.

methodsData from the DGNS (data as of 14 April 2023) and the DMR (data as of 12 April 2023) for children born between 2017 and 2021 were analyzed with regard to the frequencies of CF, number of patients with CF diagnosed after false-negative screening results, and ratio of CF to cases with positive cystic fibrosis screening and inconclusive diagnosis (CFSPID).

resultsThe DGNS has 767 datasets of newborns with CF/CFSPID and the DMR has 910 confirmed cases of CF/CFSPID. A false-negative screening was reported by the DGNS for 37/767 (4.8%) and by the DMR for 49/910 (5.4%). The ratio of CF to CFSPID is 17.4:1 (DGNS, 2017-2020) and 28.1:1 (DMR), respectively. DISCUSSION: The DGNS and the DMR, each with different strengths in the documentation of screening (DGNS) and diagnostic data (DMR), provide important clues for the number of newly diagnosed cystic fibrosis patients after the introduction of NGS. Legal requirements for tracking those screened, recording all children with CF, and exchanging data between the DGNS and DMR could improve evaluation in the future.