Association of heart rate variability index with depressive symptoms and lung function in chronic obstructive pulmonary disease

Table 2 Comparison of depressive symptoms and pulmonary function indicators in each group, mean ± SD

Variable	Without depression (n = 77)	Depression (n = 43)	Control (n = 60)	P value
BDI score	5.7 ± 4.3	21.8 ± 5.9	2.6 ± 1.5	< 0.001
Lung function
FEV1 (L)	2.86 ± 0.67	2.06 ± 0.43	3.65 ± 0.78	< 0.001
FVC (L)	2.90 ± 0.72	1.43 ± 0.82	3.46 ± 0.57	< 0.001
FEV1/FVC	72.1 ± 6.03	58.2 ± 6.73	88.2 ± 8.76	< 0.001

BDI: Beck depression inventory; FEV1: First-second expiratory volume; FVC: Forced vital capacity.