Since the year 2000, infants born in the Piedmont region of Italy have been screened for cystic fibrosis (CF). The investigators estimated the time to initial infection by Pseudomonas aeruginosa in 71 children who were diagnosed as having CF in the years 1997–2004, which includes the years before and after newborn screening was introduced. Infants were followed up for at least 12 months. Forty-four of the 71 infants in the study (62%) were diagnosed by newborn screening, while the remaining 38% were diagnosed clinically before screening came into use, by sweat chloride testing after symptoms of CF had been observed.
Introduction of newborn screening significantly lowered the median age at diagnosis of CF from 323 to 42 days. Pancreatic insufficiency was found in 35 children (50% of the newborn screen group, 48% of the clinically diagnosed group) and meconium ileus was the presenting feature in 12 (16% and 18%, respectively). P aeruginosa was diagnosed in 20 (45%) screened and 14 (52%) clinically diagnosed infants. Children diagnosed by newborn screening had a significantly shorter median time to P aeruginosa infection compared with the clinically diagnosed subjects (183 versus 448 days). Median ages at the time of initial infection were 201 and 511 days, respectively. Overall annual rates of initial infection by P aeruginosa did not differ significantly between the screened and nonscreened children. Neither univariate nor multivariate regression analyses showed a significant association between the performance of newborn screening and respiratory tract infection by P aeruginosa. Semiparametric analyses, however, showed a significant correlation between the need for pancreatic enzyme supplementation and an increased hazard ratio for P aeruginosa infection. Both screened and nonscreened children have been followed for 71 to 97 person-years; to reach a statistical power of 90%, the overall follow-up would have to be 1400 person-years.
These findings suggest that health care authorities considering the institution of newborn screening for CF should do so only in settings where infection control policies are in place.