Table S1.

General linear model for BPIFA1 mRNA expression

Parameter	B	Standard error	t	Significance
Intercept	−3.554	2.112	−1.682	0.096
Age	−0.012	0.033	−0.361	0.719
Gender
Male	0.234	0.64	0.366	0.715
Female	0a
Inhaled corticosteroids
Inhaled corticosteroid use	0.736	0.818	0.9	0.371
No inhaled corticosteroid use	0a
Smoking status
Yes	0.952	0.632	1.506	0.136
No (ex-smoker or never-smoker)	0a
COPD status
COPD III–IV	2.37	1.173	2.02	0.047
COPD II	0.256	0.719	0.356	0.723
Without COPD	0a

Notes:

^aReference parameter is set to 0. Linear regression analysis, where the natural logarithm of the mRNA 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.