Neonatal Screening for Cystic Fibrosis: Long-Term Clinical Balance

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Abstract
Very few studies have been performed on the long-term clinical advantages of neonatal screening programs for cystic fibrosis (CF) and these have been inconclusive. This is a preliminary report of two observational cohort studies on this subject.In the first study, CF patients born between 1973 and 1981 in northeastern Italy were split into 4 groups according to the modality of diagnosis: screening by meconium test (58 patients); meconium ileus (45 patients); symptoms and pancreatic insufficiency (PI; 75 patients), or symptoms and pancreatic sufficiency (PS; 19 patients). The patients were followed for up to 26 years by three CF centers sharing common treatment protocols. In the second study, two cohorts of CF patients born between 1983 and 1992 were compared. Patients from one cohort (126 patients) were born in the Veneto region, where a neonatal screening program had been established based on immunoreactive trypsinogen. Patients from the other cohort (152 patients) were born in Sicily, where an intensive program of early diagnosis by symptoms was implemented. The cohorts were comparable for CF incidence, CFTR genotypes, gender proportion and common treatment protocols. Statistical analyses were performed by Kaplan-Meier survival curves, a Cox proportional hazard model for survival and cross-sectional comparisons by 2-year periods for weight z score, height z score and body mass index.In the first study, the patients detected by newborn screening (PI) showed better survival and nutritional status compared to patients diagnosed through meconium ileus or symptom presentation with PI. PS patients diagnosed by symptoms showed the best outcome, but most of them had a mild genotype. In the second study, the Veneto cohort showed better outcome with regard to survival and nutritional status over 16 years of follow-up.Observational cohort studies cannot give definitive evidence of the clinical benefit of neonatal CF screening; however, data have been accumulated which strongly suggest a better clinical outcome for CF patients born in an area where a screening program is performed.