Table 2 Changes in health effect indicators at each follow-up visit, separately for EC users and control subjects who completed all four study visits.

From: Health impact of E-cigarettes: a prospective 3.5-year study of regular daily users who have never smoked

   Baseline F/up 1 F/up 2 F/up 3 Between effect p value
FEV1 (l, mean ± SD) EC users 3.82 ± 0.78 3.81 ± 0.78 3.78 ± 0.71 3.87 ± 0.76 0.30
Control subjects 4.08 ± 0.30 4.06 ± 0.28 4.03 ± 0.26 4.11 ± 0.30
FVC (l, mean ± SD) EC users 4.93 ± 0.95 4.80 ± 0.82 4.82 ± 0.91 4.87 ± 0.83 0.61
Control subjects 5.03 ± 0.48 4.97 ± 0.42 5.01 ± 0.45 5.02 ± 0.42
FEV1/FVC (%, mean ± SD) EC users 78.49 ± 3.46 79.01 ± 3.63 78.46 ± 2.34 79.08 ± 2.83 0.09
Control subjects 81.45 ± 5.03 82.02 ± 4.67 80.86 ± 6.18 82.06 ± 4.25
FEF25–75% (l/min, mean ± SD) EC users 3.29 ± 0.70 3.29 ± 0.60 3.30 ± 0.75 3.33 ± 0.64 0.36
Control subjects 3.43 ± 0.64 3.49 ± 0.61 3.53 ± 0.57 3.56 ± 0.58
Weight (kg, mean ± SD) EC users 71.3 ± 11.2 72.9 ± 11.5 73.3 ± 11.4 72.2 ± 11.2 0.95
Control subjects 72.9 ± 11.8 74.0 ± 12.1 73.2 ± 12.3 73.6 ± 11.8
Systolic blood pressure (mmHg, mean ± SD) EC users 115 ± 9 116 ± 5 114 ± 9 118 ± 10 0.82
Control subjects 117 ± 9 117 ± 10 116 ± 10 116 ± 9
Diastolic blood pressure (mmHg, mean ± SD) EC users 79 ± 6 78 ± 4 73 ± 9 76 ± 8 0.50
Control subjects 74 ± 9 76 ± 6 75 ± 9 73 ± 9
Heart rate (beats/min, mean ± SD) EC users 72 ± 7 71 ± 9 71 ± 9 71 ± 7 0.15
Control subjects 79 ± 9 78 ± 8 76 ± 8 78 ± 9
eCO (ppm, median and IQ range) EC users 5.0 [3.5–7.3] 4.0 [2.8–6.0] 3.0 [3.0–5.8] 4.0 [2.8–6.3] 0.21
Control subjects 4.0 [3.5–7.5] 5.5 [4.0–6.5] 7.0 [3.5–8.0] 5.0 [5.5–6.0]
FeNO (ppb, median and IQ range) EC users 21.1 [16.2–24.5] 19.7 [17.2–22.3] 18.9 [18.2–24.7] 20.0 [18.2–22.7] 0.89
Control subjects 18.6 [17.6–25.7] 19.4 [16.0–25.1] 18.7 [16.9–22.0] 20.0 [16.2–23.4]