Risk factors for forced expiratory volume in 1 s decline in European patients with cystic fibrosis: data from the European Cystic Fibrosis Society Patient Registry

Aim To examine the trajectory of forced expiratory volume in 1 s (FEV1) using data from the European Cystic Fibrosis Society patient registry (ECFPR) collected from 2008 to 2016, i.e. the era before highly effective modulator therapy (HEMT). We evaluated risk factors for FEV1 decline. Methods The study population included patients with a confirmed diagnosis of cystic fibrosis recorded in the ECFPR (2008–2016). The evolution of FEV1 % predicted (%FEV1) with age, and the yearly change in %FEV1 were evaluated. Risk factors considered were cystic fibrosis transmembrane conductance regulator (­CFTR) mutation class, gender, age at diagnosis, neonatal screening, meconium ileus, sweat chloride concentration at diagnosis and country's income level. Results We used 199 604 FEV1 recordings from 38 734 patients. The fastest decline was seen during puberty and in patients diagnosed before the age of 10 years. Males had a higher %FEV1, but a higher yearly %FEV1 loss between the ages of 15 and 25 years. We showed stabilisation and even improvement in %FEV1 over age in adults with a class III CFTR mutation, but a steady decline in patients homozygous for F508del or with both mutations of classes I/II. A faster decline in %FEV1 was found in patients from low-income countries compared to a similar %FEV1 evolution in patients from middle- and high-income countries. Conclusions These longitudinal FEV1 data reflect the reality of cystic fibrosis across Europe in the era pre-HEMT, and can serve as baseline for comparison with the post-HEMT era. The similar evolution in middle- and high-income countries underlines opportunities for low-income countries.