S7 Evolution of lung function during the first two years of life in infants with cystic fibrosis diagnosed by newborn screening

Background In contrast to findings from the Australian AREST-CF study1 infants with cystic fibrosis (CF) diagnosed by newborn screening (NBS) participating in the London CF Collaboration (LCFC) study2 were found to have relatively mild lung disease by 1 year of age when compared to healthy controls. Hypothesis In NBS CF infants, lung function remains stable to 2 years. Methods Lung clearance index (LCI), plethysmographic functional residual capacity (FRC) and forced expiratory volume (FEV 0.5 ) from the raised volume technique were measured in NBS CF infants and healthy controls at 3months (3m), 1year (1y) and 2 years (2y). Results were expressed as z-scores using equipment-specific equations to adjust for age, sex and body size. Results To date, 55 CF and 28 control infants have been assessed on all 3 occasions. The mildly elevated LCI and FRC in CF infants identified by 3m when compared with controls remained stable thereafter. The significant reduction in FEV 0.5 (mean difference (95% CI) -1.26 (-1.73; -0.79) z score) among CF infants at 3m had improved by 1y (see Figure 1). From 1 to 2 years all 3 measurements remained stable with no significant changes in average z-scores for either the CF or control infants. On average, LCI, FRC and FEV 0.5 only changed by 0.02, 0.16 and 0.06 z-scores respectively amongst CF children between 1 2 years, similar to that observed in controls. Mean (95%CI) group differences (CF-HC) in change of LCI, FRC and FEV 0.5 between 1 2y were 0.02 (-0.61; 0.66), p = 0.94;-0.05 (-0.61; 0.51), p = 0.86; and 0.32 (-0.27; 0.90) p = 0.29, respectively. Conclusions This is the first study to demonstrate stable lung function to 2y in NBS CF infants managed on standard CF therapy. These results suggest that in many of these infants novel treatments could be deferred beyond infancy when objective outcomes are more easily measured. References Pillarisetti et al. AJRCCM 2011 Hoo et al Thorax 2012.