Table 2 Linear regression analysis with presence of sleep disturbance at baseline as independent variable and COPD severity at baseline as dependent variable

 Baseline SD

−0.05

(−7.35, 2.55)

0.34

0.07

(− 0.18, 0.45)

0.40

0.22

(2.33, 12.97)

0.005

− 0.03

(−56.29, 38.98)

0.72

0.05

(−8.17, 14.59)

0.57

− 0.11

(− 10.77, 1.71)

0.15

 Baseline SD

− 0.04

(− 6.34, 2.05)

0.32

0.07

(− 0.19, 0.46)

0.42

0.22

(2.08, 13.21)

0.007

− 0.10

(− 72.10, 12.12)

0.16

−0.02

(− 12.30, 10.13)

0.85

− 0.09

(− 9.68, 2.49)

0.25

 Age

0.31

(0.82, 1.39)

< 0.001

0.11

(− 0.01, − 0.04)

0.17

− 0.01

(− 0.47, 0.40)

0.87

− 0.35

(− 11.20, −4.68)

< 0.001

−0.15

(− 1.70, 0.05)

0.07

0.02

(− 0.41, 0.53)

0.80

 Sex

0.02

(− 3.27, 5.12)

0.67

0.09

(− 0.14, 0.50)

0.27

0.07

(− 3.20, 7.90)

0.40

− 0.34

(− 140.02, − 56.77)

< 0.001

− 0.24

(− 28.44, − 6.06)

0.003

−0.09

(− 9.67, 2.47)

0.24

 Race

−0.04

(− 15.04, 5.11)

0.33

0.12

(− 0.18, 1.51)

0.12

0.06

(− 9.34, 19.84)

0.48

− 0.04

(− 136.17, 80.11)

0.61

0.07

(− 16.46, 42.30)

0.39

−0.10

(− 25.96, 5.96)

0.22

 BMI

0.21

(0.70, 1.54)

< 0.001

− 0.07

(− 0.06, − 0.03)

0.44

− 0.03

(− 0.82, 0.57)

0.72

−0.17

(− 11.55, − 0.90)

0.02

−0.21

(− 3.19, − 0.38)

0.01

0.34

(0.86, 2.38)

< 0.001

 Smoking status

− 0.40

(− 28.39, − 18.82)

0.35

0.10

(− 0.14, 0.53)

0.24

0.01

(− 5.30, 6.22)

0.16

− 0.10

(− 74.06, 13.69)

0.18

− 0.13

(− 12.34, 10.57)

0.90

− 0.19

(− 13.87, − 1.27)

0.02