Lung function decline is delayed but not decreased in patients with cystic fibrosis and the R117H gene mutation

Background: Patients with cystic fibrosis (CF) experience variable lung disease phenotypes. The R117H mutation is often associated with preserved lung function. Our objective was to compare the rate of lung function decline in patients with the R117H mutation and patients homozygous for the F508del mutation. Methods: Rate of decline in percentage-of-predicted FEV1 (ppFEV(1)) was analyzed using the 2006-2010 US CF Foundation Patient Registry. Results: 4-year rate of decline was slower in 156 R117H patients compared with 6251 F508del patients (0.61 vs -2.03 ppFEV(1)/year, P < 0.001). Rates of decline in children were slower in R117H vs F508del patients (6-12-year-olds: +0.73 vs -1.91 ppFEV(1)/year, P < 0.001 and 13-17-year-olds: -1.55 vs - 2.66 ppFEV(1)/year, P = 0.046), whereas rates in adults were not significantly different (18-24-year-olds: -1.52 vs -2.12, P = 0.26 and >= 25-year-olds: -1.17 vs -1.40, P = 0.33). Conclusions: These findings are consistent with a delayed onset, but ultimately similar progression, of lung disease in R117H compared with homozygous F508del patients. (C) 2017 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.