Table 2.

Correlation analysis of traditional spirometric parameters and selected variables

	FEV1		FEV1/FVC		RV/TLC		PEF		IC
	r a	P-value	r a	P-value	r a	P-value	r a	P-value	r a	P-value
RV/TLC	−0.881 *	<0.001	−0.702 *	<0.001	–	–	−0.765 *	<0.001	−0.148	0.512
SGRQ	−0.355	0.105	−0.140	0.534	0.447 *	0.037	−0.306	0.202	−0.073	0.747
6MWD	0.201	0.371	0.042	0.853	−0.257	0.249	0.441	0.058	0.611 *	0.003
CAT	−0.226	0.313	−0.026	0.909	0.277	0.213	−0.233	0.337	−0.046	0.838

Abbreviations: FEV ₁ forced expiratory volume in one second, FVC forced vital capacity, RV residual volume, TLC total lung capacity, IC inspiratory capacity, PEF peak expiratory flow, SGRQ St. George’s respiratory questionnaire, 6MWD 6-min walking distance, CAT the chronic obstructive pulmonary disease assessment test

^a r: Pearson’s correlation coefficient, adjusted for age, BMI and smoking

*P-value < 0.05