Table 4– Multivariate stepwise analysis of all subjects with each plasma or sputum biomarker as the dependent variable#
βt-testp-value
Plasma sRAGE
DLCO % pred0.3532.6150.012
Plasma SP-A
 FEV1/FVC %-0.370-2.7960.008
Sputum MPO
 Neutrophil in sputum %0.3712.9080.005
Sputum NGAL
 FEV1 % pred-0.427-3.497<0.001
  • sRAGE: soluble receptor for advanced glycation end-products; DLCO: diffusing capacity of the lung for carbon monoxide; % pred: % predicted; SP-A: surfactant protein A; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MPO: myeloperoxidase; NGAL: neutrophil gelatinase-associated lipocalin. #: multivariate analysis was adjusted for age, body mass index, current smoking status, pack-years, inhaled corticosteroid use, and all the significant variables in the univariate analysis.