[Screening of newborn infants in cystic fibrosis. Evaluation of a 4-year study in Switzerland].

The results of an evaluation over 4 years (1973-1976) of 16,620 BM-tests (Boehringer-Mannheim newborn screening for cystic fibrosis) at 8 hospitals in Switzerland are presented and the data from analysis of albumin, protein and alpha1-antitrypsin concentrations, and on trypsin-inhibitory capacity of the meconia are discussed. 99.5% of the tests were negative. Of the remaining 0.5% BM-positive tests, the diagnosis of cystic fibrosis required confirmation by sweat test and clinical course in 6 cases, or 0.04% of the total collective. The test was false-negative in 2 cases (0.012%), of which one had a primary pulmonary form of cystic fibrosis. The study shows that the BM-test, as screening test for cystic fibrosis, makes it possible to distinguish between "normal" and "suspect". By calculating the ratio albumin to alpha1-antitrypsin, it would be possible to verify the probability of a reliable diagnosis as early as a few days after birth. As before, however, it would be indispensable to confirm the diagnosis of cystic fibrosis by a sweat test with pilocarpin iontophoresis. By consistent screening in all obstetric and pediatric clinics it would be possible to improve early diagnosis still further.