Pulmonary function tests
PFTs that were performed as part of the ViDAS trial included spirometry [forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), forced expiratory flow rate at 25–75% (FEF25-75%), ratio of FEV1 and FVC (FEV1/FVC)] lung volume measurements (total lung capacity (TLC), residual volume (RV)], diffusing capacity of the lungs for carbon monoxide (D