Table 2 Comparison of controls and e-Cigarette users at baseline, 12-month and 24-month follow-up visits

 post-BD FEV1^a (L)

1.47 (1.13, 1.72)

1.43 (1.12, 172)

0.538

1.45 (1.17, 1.66)

0.657

0.223

 post-BD FVC^a (L)

2.39 (2.1, 2.64)

2.35 (2.2, 2.74)

0.065

2.35 (2.19, 2.83)

0.141

0.977

 %FEV1/FVC^b

56.2 (±10.3)

55.9 (±10.1)

0.328

56.3 (±10.1)

0.277

0.033

 Cig/day^b

20.5 (±3.3)

20.1 (±3.7)

0.371

19.8 (±5)

0.296

<0.001

 CAT score^a

20.5 (17.8, 24.3)

20 (17.5, 24.3)

0.075

20 (15.8, 24)

0.361

0.001

 COPD Exacerbations^b

2.1 (±1.1)

2.2 (±1)

0.906

2.1 (±1.1)

0.819

0.005

 6MWD^{a, c}

267.3 (195, 351.5)

270 (210.3, 372)

0.056

270.5 (220.8, 373.9)

0.096

0.002

 post-BD FEV1^a (L)

1.25 (0.94, 1.78)

1.23 (0.93, 1.73)

0.102

1.29 (0.92, 1.67)

0.153

 post-BD FVC^a (L)

2.37 (2, 2.65)

2.45 (1.92, 2.73)

0.081

2.46 (1.84, 2.86)

0.252

 %FEV1/FVC^b

59.4 (±8.4)

58.3 (±8.6)

0.457

57.9 (±8.5)

0.483

 Cig/day^b

21.8 (±4.4)

1.8 (±2.2)

<0.001

1.58 (±2)

<0.001

 CAT score^a

21.5 (17.8, 25.3)

17.5 (15.8, 20.5)

<0.001

18 (15, 20)

<0.001

 COPD Exacerbations^b

2.3 (±1)

1.8 (±1)

0.002

1.4 (±0.9)

<0.001

 6MWD^{a, c}

266.5 (187.5, 313.5)

307 (219.5, 342)

0.002

327 (239.5, 359.5)

0.002