JMIR Publications

ABSTRACT

Background:

While smoking cessation has been linked to substantial weight gain, the potential influence of electronic cigarettes (e-cigarettes) on weight changes among individuals who use these devices to quit smoking is not fully understood. We reanalyze data from the E3 trial to assess causal effects of e-cigarette usage on change in body weight.

Objective:

The objective of this study is to determine whether electronic cigarettes mitigate the weight gain that is observed in smokers who quit smoking.

Methods:

This is a secondary analysis of the E3 smoking cessation trial where participants were randomized into three groups: nicotine e-cigarettes plus counseling, nonnicotine e-cigarettes plus counseling, and counseling alone. With adjustment for baseline variables and the follow-up smoking abstinence status, weight changes are compared between groups from baseline to 12 weeks follow-up. Intention-to-treat and as-treated analyses are conducted using doubly robust estimation (DRE). Further causal analysis utilizes two different inverse probability weighting (IPW) methods to estimate causal regression curves for four (e-)cigarette-related variables. We evaluate five different subsets of data for each method. Selection bias is addressed and missing data are imputed by the machine learning method XGBoost.

Results:

A total of 257 individuals with measured weight at week 12 (mean age, 52 years; 122 women [47%]) are included. Across the three treatment groups, 204 (79%) individuals who continued to smoke have, on average, largely unchanged weight at 12 weeks, with comparable mean weight gain varying from -0.24 kg to 0.33 kg; 53 (21%) smoking-abstinent individuals gained weight, with a mean weight gain ranging from 2.05 kg to 2.70 kg. Following adjustment, our analyses show that e-cigarettes have small and variable causal effects on weight gain associated with smoking cessation.

Conclusions:

E-cigarettes appear to have minimal effects on mitigating the weight gain observed in individuals who smoke and subsequently quit at three months. Clinical Trial: NCT02417467 (www.clinicaltrials.gov)