A retrospective cohort study of children diagnosed with cystic fibrosis after implementation of a newborn screening program in Turkey

Abstract

Introduction Newborn screening (NBS) for cystic fibrosis (CF) facilitates early diagnosis and has been shown to significantly improve long-term clinical outcomes. In this study, we aimed to evaluate the 7-year results of the immunoreactive trypsinogen (IRT)/IRT NBS of Turkey. Methods The study included all CF patients who were born after NBS implementation, and who were enrolled in the CF Registry of Turkey (CFRT) in 2022. Patients were divided into three groups according to NBS results: Group 1 with positive NBS, Group 2 with negative NBS, and Group 3 with no screening or unknown screening results. All clinical and demographic data were compared between the three groups. Results A total of 853 patients were included in the study, 668 (78.3%) patients were in Group 1, 90 (10.5%) in Group 2, and 95 (11.2%) in Group 3. The age at diagnosis was 0.17 (0.08-0.33) years in Group 1, 0.50 (0.25-1.0) in Group 2, and 0.33 (0.17-0.75) in Group 3 (p<0.001). The first and second sweat test results and frequency of pancreatic insufficiency were lowest in Group 2 (p<0.05). Median FEV1 (%) was 88 (77-103) in Group 1, 90 (71.5-104) in Group 2, 89.5 (81.75-97.5) in Group 3 (p>0.05). 49% of the patients had a severe genotype and it was detected most frequently in Group 1 (p=0.021). Conclusions Patients with pancreatic sufficiency may be missed by IRT/IRT NBS and lower and negative sweat test results may contribute to delays in CF diagnosis. Approximately 22% of patients are not diagnosed through this screening method.