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Meta-Analysis
. 2023 Mar;118(3):539-545.
doi: 10.1111/add.16063. Epub 2022 Oct 21.

Biomarkers of potential harm in people switching from smoking tobacco to exclusive e-cigarette use, dual use or abstinence: secondary analysis of Cochrane systematic review of trials of e-cigarettes for smoking cessation

Jamie Hartmann-Boyce  1 , Ailsa R Butler  1 , Annika Theodoulou  1 , Igho J Onakpoya  2 , Peter Hajek  3 , Chris Bullen  4 , Nancy A Rigotti  5 , Nicola Lindson  1
Affiliations
Meta-Analysis

Biomarkers of potential harm in people switching from smoking tobacco to exclusive e-cigarette use, dual use or abstinence: secondary analysis of Cochrane systematic review of trials of e-cigarettes for smoking cessation

Jamie Hartmann-Boyce et al. Addiction. 2023 Mar.

Abstract

Aims: This study aims to compare biomarkers of potential harm between people switching from smoking combustible cigarettes (CC) completely to electronic cigarettes (EC), continuing to smoke CC, using both EC and CC (dual users) and using neither (abstainers), based on behaviour during EC intervention studies.

Design: Secondary analysis following systematic review, incorporating inverse variance random-effects meta-analysis and effect direction plots.

Setting: This study was conducted in Greece, Italy, Poland, the United Kingdom and the United States.

Participants: A total of 1299 adults smoking CC (nine studies) and provided EC.

Measurements: Measurements were conducted using carbon monoxide (CO) and 26 other biomarkers.

Findings: In pooled analyses, exhaled CO (eCO) was lower in EC versus EC + CC [mean difference (MD) = -4.40 parts per million (p.p.m.), 95% confidence interval (CI) = -12.04 to 3.24, two studies] and CC (MD = -9.57 p.p.m., 95% CI = -17.30 to -1.83, three studies). eCO was lower in dual users versus CC only (MD = -1.91 p.p.m., 95% CI = -3.38 to -0.45, two studies). Magnitude rather than direction of effect drove substantial statistical heterogeneity. Effect direction plots were used for other biomarkers. Comparing EC with CC, 12 of 13 biomarkers were significantly lower in EC users, with no difference for the 13th. Comparing EC with dual users, 12 of the 25 biomarkers were lower for EC, and five were lower for dual use. For the remaining eight measures, single studies did not detect statistically significant differences, or the multiple studies contributing to the outcome had inconsistent results. Only one study provided data comparing dual use with CC; of the 13 biomarkers measured, 12 were significantly lower in the dual use group, with no statistically significant difference detected for the 13th. Only one study provided data on abstainers.

Conclusions: Switching from smoking to vaping or dual use appears to reduce levels of biomarkers of potential harm significantly.

Keywords: Electronic cigarettes; biomarkers; carbon monoxide; smoking cessation; systematic review; tobacco.

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Conflict of interest statement

A.R.B., A.T., J.H.B., N.L., I.O.: none to declare. P.H. provided consultancy to and received research funding from Pfizer. C.B. is an investigator on grants and contracts for research on tobacco control from the Health Research Council of NZ, the NHMRC Australia, NZ Ministry of Health and Auckland Council. He has provided consultancy to J&J Japan on NRT products. N.A.R. has received royalties from UpToDate, Inc., for chapters on electronic cigarettes. Outside the topic of e‐cigarettes, she has consulted for and received a research grant from Achieve Life Sciences.

Figures

FIGURE 1
FIGURE 1
Exhaled carbon monoxide (eCO) [parts per million (p.p.m.)], electronic cigarettes (EC) versus combustible cigarettes (CC). (1) Absolute at 1 month; no significant differences at baseline. CC = those in EC condition who used CC only at follow‐up (FU) [control group of CC only mean 16.4; standard deviation (SD) = 0.7]. (2) Values are absolute at 12 weeks; no significant between‐group differences at baseline. (3) Values are absolute at 8 months (1 and 4 months also available); no significant between‐group differences at baseline. CC group also significantly reduced CC consumption [from 27 cigarettes per day (CPD) to eight CPD]. All groups had notably low CO at baseline
FIGURE 2
FIGURE 2
Exhaled carbon monoxide (eCO) [parts per million (p.p.m.)], electronic cigarettes (EC) versus EC + combustible cigarettes (CC). (1) Values are absolute at 1 month; no significant between‐group differences at baseline. (2) Values are absolute at 8 months (1 and 4 months also available); no significant between‐group differences at baseline. EC + CC group also had significantly reduced CC consumption [from 23 cigarettes per day (CPD) to five CPD]. All groups had notably low CO at baseline. (3) Change data at 4 weeks
FIGURE 3
FIGURE 3
Exhaled carbon monoxide (eCO) [parts per million (p.p.m.)], electronic cigarettes (EC) + combustible cigarettes (CC) versus CC. (1) Values are absolute at 1 month; no significant between‐group differences at baseline. CC = those in EC condition who used CC only at follow‐up (FU) [control group of CC only mean 16.4; standard deviation (SD) = 0.7]. (2) Values are absolute at 8 months (1 and 4 months also available); no significant between‐group differences at baseline. Both groups significantly reduced CC consumption (EC + CC from 23 CPD to five CPD; CC from 27 CPD to eight CPD). All groups had notably low CO at baseline
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References

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