AF	Affinity chromatography
AUC	Area under the curve
COPD	Chronic obstructive pulmonary disease
COPD-LC	COPD patients who developed LC
COPD-vs	Very severe COPD
COPD-s	Severe COPD
COPD-mo	Moderate COPD
COPD-mi	Mild COPD
CHAiN	COPD History Assessment in SpaiN
HC	Healthy control
ICP-MS	Inductively coupled plasma mass spectrometry
LC	Lung cancer
LOD	Limits of detection
LOQ	Limits of quantification
PCA	Principal component analysis
PLS-DA	Partial least squares-discriminant analysis
ROC	Receiver operating characteristic
VIP	Variable importance in projection