Introduction
The life expectancy and quality of life of patients with Cystic fibrosis (CF) have greatly increased over the last decades. Early diagnosis, preventive treatment, prompt and aggressive management of pulmonary exacerbations (PEx) and complications, and treatment with CFTR modulators have led to improved outcome1,2. However, lung disease continues to be the major cause of morbidity and mortality in CF1,3.
Forced expiratory volume in 1 second (FEV1), measured by spirometry, is considered the gold standard for disease severity in CF. It is being used routinely to monitor lung disease status, to determine the need for lung transplantation, to measure the response to therapies and as an outcome measure in clinical trials4,5. Lung disease severity is commonly categorized according to FEV1 %predicted and is considered normal at> 80% predicted. Therefore, FEV1measurements over time serve as a guide for physicians, patients, parents and caregivers in the management of the disease and as indicator for treatment intensity. Normal FEV1 may be falsely interpreted as having lungs that are free of disease, and may influence treatment recommendations and adherence.
Studies, mainly of preschool and young children, have demonstrated that the lung clearance index (LCI) may be abnormal in patients with mild lung disease according to FEV16-9. Other studies on small numbers of young patients, with normal pulmonary function, demonstrated abnormalities in chest CT. To the best of our knowledge, there is no comprehensive evaluation of lung disease severity for patients above early childhood, who have normal pulmonary function measured by FEV1.
The aim of this study was to perform a broad assessment of the extent of lung disease in patients with CF with FEV1>80% of all age groups, as determined by clinical, physiological and structural characteristics of CF disease severity.