WS3.4 Determinants of lung disease progression in children with CF

Abstract

Ireland has the world’s highest incidence of Cystic Fibrosis at approximately 1 in 1400 [1,2]. CF was integrated into the newborn bloodspot screening programme in July 2011 using an IRT/ DNA analysis strategy. Babies with a blood IRT above the 99th percentile and with one or two CFTR mutations detected are referred for sweat testing. The anticipated number of CF cases (54) and carriers (94), were calculated based on the birth rates from the 2008 census and assuming a 2.5-fold enrichment of carriers within the top IRT percentile. During the first 6 months of the programme, 37,435 babies were screened and 391 (1.0%) were referred for DNA testing. 16 CF cases (all with 2 mutations and confirmed by sweat testing) and 35 unaffected carriers were detected, giving an annualised CF incidence of 1 in 2340. Just 59% of the predicted number of CF cases (p = 0.038) and 74% of the predicted number of unaffected carriers (p = 0.014) were detected. Data from 2010 indicates that 25% of newborns in Ireland had non-Irish mothers. When the expected numbers were recalculated, based on the CF incidence in the nationality of the mother (and assuming the father has the same nationality), 72% of expected cases (p = 0.187) and 100% of expected unaffected carriers were detected. The apparent reduction in the number of cases and the changing incidence of CF in Ireland may reflect the significant increase in immigration (particularly from Eastern Europe) since 2004, after the published CF incidence figures were calculated.