. 2020 Nov 18;3(11):e2026324. doi: 10.1001/jamanetworkopen.2020.26324

Table 2. Effect of e-Cigarettes on Biomarkers of Exposure and Short-term Cardiopulmonary Outcomes.

Variable	Within-group change from baseline				Between-group change
	e-Cigarette (n = 125)		Control (n = 61)		Between-group change
	RR (95% CI)	P value	RR (95% CI)	P value	RR (95% CI)	P value
NNAL at week 6, pg/mL^a^,^b	0.33 (0.26-0.42)	<.001	0.92 (0.65-1.30)	.64	0.36 (0.23-0.54)	<.001
Cotinine at week 6, ng/mL^a	0.93 (0.77-1.12)	.45	1.17 (0.90-1.53)	.25	0.80 (0.58-1.10)	.17
Carbon monoxide, ppm
Week 2	0.45 (0.38-0.52)	<.001	0.98 (0.79-1.22)	.87	0.46 (0.35-0.59)	<.001
Week 6	0.48 (0.41-0.55)	<.001	0.89 (0.73-1.09)	.27	0.53 (0.42-0.68)	<.001
Cigarettes, past 7 d, No.^c
Week 2	0.23 (0.18-0.30)	<.001	0.95 (0.73-1.23)	.68	0.25 (0.17-0.36)	<.001
Week 6	0.23 (0.18-0.30)	<.001	0.77 (0.59-1.01)	.06	0.30 (0.20-0.43)	<.001
Respiratory symptoms, per point
Week 2	0.90 (0.78-1.05)	.18	1.20 (0.97-1.47)	.09	0.75 (0.59-0.97)	.03
Week 6	0.70 (0.60-0.83)	<.001	1.11 (0.87-1.42)	.39	0.63 (0.47-0.85)	.002
Lung function, FEF_25%-75%, L/s^d
Week 2	0.99 (0.92-1.07)	.80	1.01 (0.91-1.11)	.91	0.98 (0.87-1.12)	.81
Week 6	0.96 (0.88-1.04)	.32	1.01 (0.89-1.14)	.93	0.95 (0.82-1.11)	.53
Systolic blood pressure, mm Hg
Week 2	1.00 (0.98-1.02)	.84	1.01 (0.98-1.04)	.63	0.99 (0.96-1.03)	.78
Week 6	1.01 (0.98-1.03)	.58	1.03 (0.99-1.06)	.14	0.98 (0.94-1.02)	.36
Diastolic blood pressure, mm Hg
Week 2	0.99 (0.97-1.02)	.64	1.00 (0.97-1.03)	.86	1.00 (0.96-1.04)	.90
Week 6	1.00 (0.98-1.02)	.84	1.00 (0.97-1.03)	.96	1.00 (0.97-1.04)	.87

Abbreviation: FEF_25%-75%, midexpiratory forced expiratory flow; NNAL, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; RR, relative risk.

^{^a}

Normalized for creatinine.

^{^b}

One sample missing.

^{^c}

From 7-day timeline follow-back among continuing smokers only.

^{^d}

Mean forced expiratory flow between 25% and 75% of forced vital capacity.