Pulmonary and other health effects of electronic cigarette use among adult smokers participating in a randomized controlled smoking reduction trial

Abstract

Background: There is limited evidence about the effects of dual electronic cigarette (e-cig) and combustible cigarette use on lung health or other health outcomes. Studies that have evaluated these outcomes have not included estimates of e-cig or cigarette exposure in the analyses.

Materials and methods: Data analyzed were from 263 smokers participating in a randomized controlled trial designed to encourage participants to reduce their combustible cigarette use by substituting with an e-cig or a non-electronic cigarette substitute (cig-sub). t-tests were used to evaluate changes from baseline at 1 month and 3 months in lung function, blood pressure, pulse, exhaled carbon monoxide, and weight. Linear mixed effects models were used to test associations between health outcomes and study product group, including exposure to the study products (e-cig and cig-sub times used and days used in the past 7 days) and cigarettes per day (CPD).

Results: There were few significant differences between the groups for lung function indices at any time point in the unadjusted analyses. There were significant reductions in diastolic blood pressure and pulse at 1 month in the unadjusted analyses for those in the e-cig group compared to the cig-sub group. CPD decreased significantly more for the e-cig group than for the cig-sub group at both time points. There were no significant associations between any measured health outcomes and group in the linear mixed effects models.

Conclusion: E-cig use did not contribute to significant changes in health outcome markers as compared with use of a non-electronic cig-sub.

Keywords: Electronic cigarettes; Health effects; Lung function; Smoking reduction.

Figure 1:

Schema of study visits and measurements taken *Abbreviations: CO=Exhaled carbon monoxide, PSCDI= Penn State Cigarette Dependence Index

Figure 2:

Mean days used e-cig or cig-sub (a), mean times used e-cig or cig-sub (b), and mean change from baseline in cigarettes per day (CPD) by group at the 1-month and 3-month follow-up (c) (* indicates significant difference between groups, p<0.05)

Figure 3†:

Unadjusted change from baseline in exhaled carbon monoxide, select spirometry indices, blood pressure, and weight by group at 1-month and 3-month follow up (* indicates significant difference between groups, p-values <0.05). ^†In the linear mixed effects models, based on the results of the interaction terms for the randomization group and visit, after adjusting for demographics and change in CPD, e-cig or cig-sub times used, and days used the e-cig or cig-sub, there were no significant differences between the groups. Abbreviations: E-cig=Electronic cigarette, Cig-sub=Cigarette substitute, CO=Exhaled carbon monoxide, FEV1=Forced expiratory volume in 1 second; FVC=Forced vital capacity, FEV1/FVC%=FEV1/FVCratio, FEF 25–75=Forced expiratory flow at 25–75% of FVC, FET=Forced expiratory time, BP=Blood pressure.