Demographic and clinical variables
Variables such as age, gender, type of CFTR mutation, Body Mass Index (BMI), and pancreatic sufficiency were obtained from pwCF using a demographic questionnaire which was then verified with the medical record. Lung function (Forced expiratory volume in one second) was assessed using the Masterscreen ( Jaeger®, CareFusion Corporation) during clinical visits. Before assessing lung function, short or long acting β2-adrenergic agonists were stopped for 12 hours.