Table 4. Multiple linear regression model for the predictors of spirometric pulmonary function changes after the 3-month treatment.

Characteristics	FEV1 change (mL)			FVC change (mL)
	Standardized coefficient (β)	P value		Standardized coefficient (β)	P value
Age	0.032	0.801		−0.046	0.690
BMI	0.088	0.474		0.032	0.789
Smoking pack-years	0.042	0.722		0.198	0.079
Current smoking status (current vs. ex-smoker)	0.026	0.832		0.122	0.283
FEV1 (% predicted)	0.341	0.008
FVC (% predicted)				0.402	0.001
DLco (% predicted)	0.035	0.803		0.007	0.961
IC/TLC (%)	0.167	0.206		0.009	0.939
mMRC dyspnea scale	0.175	0.211		0.150	0.255
CAT score	0.056	0.657		0.133	0.266

FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; BMI, body mass index; DLco, diffusing capacity for carbon monoxide; IC, inspiratory capacity; TLC, total lung capacity; mMRC, Modified Medical Research Council; CAT, COPD Assessment Test.