Table 2 Pearson product moment correlation coefficient of all variables.

	Pearson's correlation, r	p Value
FEV1 vs symptom score	−0.294	0.006
FEV1 vs activity score	−0.536	<0.001
FEV1 vs impact score	−0.417	<0.001
FEV1 vs total score	−0.464	<0.001
FEV1 vs 6MWD	0.351	0.001
6MWD vs symptom score	−0.272	0.011
6MWD vs activity score	−0.536	<0.001
6MWD vs impact score	−0.459	<0.001
6MWD vs total score	−0.483	<0.001

FEV1, forced expiratory volume in 1 s; 6MWD, 6 min walk distance.