Supplementary material 12 to: Electronic cigarettes for smoking cessation

Lindson N, Livingstone-Banks J, Butler AR, McRobbie H, Bullen CR, Hajek P, Wu AD, Begh R, Theodoulou A, Ma C, Notley C, Rigotti NA, Turner T, Fanshawe T, Hartmann-Boyce J
https://doi.org/10.1002/14651858.CD010216.pub11

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Carbon monoxide (CO) data not contributing to meta-analyses

Study ID

Intervention/ comparator

Time point

Data

Between-group difference[1] (↑ higher in EC/higher dose EC arm; ↔ equivocal; ↓ lower in EC/higher dose arm)

Cravo 2016*

Nicotine EC versus combustible cigarettes

2 weeks

“At baseline, eCO was at 20.3 ppm (±8.4) in EVP subjects and at 21.3 ppm (±9.2) in CC subjects. In the EVP group, eCO levels dropped to 7.4 ppm at Week 1 and were between 7.6 and 9.0 ppm from Week 2 to EoS (eCO levels in non-smokers are typically ≤6 ppm (Bedfront, 2016)). In the CC group, eCO remained at levels close to baseline during the whole study (21.3–23.3 ppm).”

Czoli 2019

Nicotine EC v combustible cigarette

1 week

Compared to baseline (dual use):

EC -41%

Traditional cigarette +21%

Eisenhofer 2015

Nicotine EC v NRT

3 weeks

Both EC and NRT groups had "significantly reduced" CO. Between-group differences were not reported.

NE

George 2019

Nicotine EC v non-nicotine EC v combustible cigarettes

4 weeks

CO measured, but not reported in detail. Lowest tertile of CO at end of study was in those with “best compliance with EC and least dual use”

NE

Meier 2017

Nicotine EC v non-nicotine EC

1 week

Randomized crossover trial. eCO: Naturalistic (whilst smoking, no EC) mean 11.4 (SE 1.3), Nicotine EC 11.6 (SE 1.3), Non-nicotine EC 10.2 (SE 1.3)

NCT03113136

EC v combustible cigarettes

4 and 12 weeks

“At 4 and 12 weeks, the CO levels were reduced in dual users of combustible tobacco and e-cigarettes (LWe or HWe), compared to exclusive combustible tobacco users.”

Tseng 2016

Nicotine EC v non-nicotine EC

1 and 3 weeks

No between-group difference in eCO was observed at any time point, no further data available

Walker 2020

Nicotine EC + NRT v non-nicotine EC + NRT v NRT only

6 months

20% nicotine EC arm; 10% non-nicotine EC arm; 4% NRT only arm had eCO < 8ppm at follow-up

Yingst 2020

Nicotine EC (36 mg/ml; refillable) versus nicotine EC (24 mg/ml; cig-a-like)

1 week

N = 17

“CO significantly decreased from baseline during the button-operated ENDS use period from 24.1 ppm (SD = 12.2) to 18.4 ppm (SD = 13.8) (p = .03), but did not significantly decrease during the cigalike use period (22.4 ppm (SD = 12.8) vs. 18.1 ppm (SD = 13.8) (p = .07)). Total CO reduction was not different between ENDS devices (p= .75).”

[1] NE: not estimable