Table S3.

General linear model for BPIFA1 protein expression

Parameter	B	Standard error	t	Significance
Intercept	−7.271	2.162	−3.363	0.001
Age	0.026	0.033	0.789	0.432
Gender
Male	0.425	0.622	0.684	0.496
Female	0a
Inhaled corticosteroids
Inhaled corticosteroid use	0.108	0.807	0.134	0.893
No inhaled corticosteroid use	0a
Smoking status
Yes	1.339	0.585	2.289	0.025
No (ex-smoker or never-smoker)	0a
COPD status
COPD III–IV	4.069	1.211	3.359	0.001
COPD II	2.140	0.664	3.223	0.002
Without COPD	0a

Notes:

^aReference parameter is set to 0. Linear regression analysis, where the natural logarithm of the protein expression of BPIFA1 is designated as the dependent variable; gender as a fixed factor; COPD status, smoking status, and inhaled corticosteroids as random factors; and age as a covariate.

Abbreviation: COPD, chronic obstructive pulmonary disease.