Association between carrier screening and incidence of cystic fibrosis

Context A downward trend in cystic fibrosis (CF) birth incidence has been reported in some areas. Objective To evaluate the association between carrier screening and CF birth incidence. Design, Setting, and Participants In northeastern Italy, CF birth incidence is monitored by means of a long-standing neonatal screening program. In the same area, 2 sections using different carrier detection approaches were identified—the western region, in which CF carrier tests are offered only to relatives of patients or to couples planning in vitro fertilization; and the eastern region, in which carrier testing is offered to relatives and carrier screening to infertile couples and to couples of reproductive age. A total of 779 631 newborns underwent CF neonatal screening between January 1993 and December 2007, of whom 195 had CF detected. Main Outcome Measure Cystic fibrosis birth incidence in the 2 regions. Results A time-related decrease in birth incidence was found, with a mean annual percentage decrease of 0.16 per 10 000 neonates (P < .001). In the western region, 2559 carrier tests were performed, 314 carriers were identified, and 9 carrier couples were detected. In the eastern region, 87 025 carrier tests were performed, 3650 carriers were identified, and 82 carrier couples were detected. The birth rate decrease was greater in the eastern region (decrease rate, 0.24; 95% confidence interval [CI], 0.12-0.36) than in the western region (decrease rate, 0.04; 95% CI, –0.16 to 0.08; P = .01). The increase in the number of screened carriers over time was significantly correlated with the decrease in CF birth incidence (correlation coefficient = −0.53; 95% CI, –0.20 to –0.74; P = .003). Conclusion In northeastern Italy, carrier screening was associated with a decrease in the incidence of CF.