Assessment of the effectiveness of a new neonatal screening algorithm for cystic fibrosis

Abstract

Relevance All over the world, neonatal screening protocols are being improved in order to reduce the time of diagnosis, simplify the examination procedure, and reduce the number of false positive and false negative results of neonatal screening. In most European countries, the best neonatal screening algorithm is molecular genetic testing. Objective: Evaluate the effectiveness of the new cystic fibrosis screening protocol algorithm, which, in the first step, determines the immunoreactive trypsin (IRT) level from one dry spot and performs DNA diagnostics (36 most frequent mutations) in patients with increased IRT. Compare the economic costs of screening by two algorithms (existing and alternative). Materials and methods: two parallel algorithms were used for neonatal screening. Which was performed on 56,534 infants in the Moscow Region from March to November 2022. The current three-stage algorithm was used, which involves re-blood sampling from newborns at risk 3-4 weeks after the first blood sampling and a sweat test. In the new algorithm, newborns with an elevated IRT 1 level at the 1st week of life underwent a molecular genetic study (search for frequent mutations in the CFTR-36 variants gene, sequencing of individual locus of the CFTR gene for control purposes) in the same dry blood spot used for screening. Results: out of 56,534 test forms received, 607 (1.07%) newborns with a positive test for IRT were identified for neonatal screening in a laboratory from the Moscow region, of which 501 (82.5%) samples were selected, where the level of RTI1 exceeded the cut-off level (65 ng / ml), which were sent for molecular genetic research in order to search for pathogenic variants in the CFTR gene. 106 (17.5%) newborns did not complete the examination. Positive results of confirmatory diagnosis were obtained in 6 infants, which accounted for 0.01% of the number of children who underwent screening and 1.2% of the number of children with neonatal hypertrypsinogenemia. Conclusion: the positive effects of the new algorithm are to reduce psychological tension in families during examination by reducing the time of diagnosis, no need for repeated blood sampling on the 21st-28th day of life, reduction of the time of diagnosis, prevention of nutritional deficiencies in children during the first months of life and life-threatening complications. Reducing the number of children with incomplete testing for cystic fibrosis, economic benefit. The negative effects of the new algorithm are that it is possible to miss a patient with cystic fibrosis who does not have any of the common pathogenic variants in the CFTR gene.