Airflow limitation or static hyperinflation: which is more closely related to dyspnea with activities of daily living in patients with COPD?

Table 2 Correlations of the BDI score with airflow limitation and static hyperinflation.

	Spearman's rank correlation coefficients		Pearson's correlation coefficient
	Rs	p value	R	p value
Dyspnea vs. Airflow limitation
BDI score vs. FEV₁ (L)	0.60	< 0.0001	0.60	< 0.0001
BDI score vs. FEV₁ (%pred)	0.56	< 0.0001	0.57	< 0.0001
BDI score vs. FEV₁/FVC	0.56	< 0.0001	0.57	< 0.0001
Dyspnea vs. Static Hyperinflation
BDI score vs. IC (L)	0.45	< 0.0001	0.48	< 0.0001
BDI score vs. IC/predicted TLC	0.46	< 0.0001	0.51	< 0.0001
BDI score vs. IC/TLC	0.47	< 0.0001	0.48	< 0.0001

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