Richa Mukerjee and colleagues’ new paper, “ENDS, cigarettes, and respiratory illness: Longitudinal associations among US youth,” adds strong evidence to the conclusion that e-cigarettes cause lung disease (bronchitis, pneumonia, or chronic cough) among young people (age 12-17). They used 6 years of longitudinal data (where you follow the same people forward in time) to measure the risk of e-cigarette use, cigarette smoking or dual use (using both products) on lung disease a year later. After accounting for the usual demographics as well as secondhand smoke exposure, cannabis use, and the presence of asthma, they found that exclusive e-cigarette use increased the risk of diagnosed lung disease by a factor of 1.49 (incidence rate ratio [IRR] = 1.49; 95% CI 1.06-2.08) compared to nonusers. The e-cigarette risk is a little lower than the 1.85 increase in risk from exclusive cigarette smoking (IRR = 1.85; 95% CI 1.29-2.65), but this difference is not statistically significant (p=0.39 by z test; my calculation). Most important, dual use nearly tripled the risk of respiratory disease (IRR = 2.70, 95% CI 1.61-3.50).
Mukerjee and colleagues did a very thorough analysis, including several sensitivity analyses: (1) They redid the analysis excluding people who had asthma at baseline (rather than adjusting for asthma in their statistical model); (2) they excluded people who were diagnosed with bronchitis, pneumonia, or chronic cough at baseline; and (3) they excluded people who were diagnosed with respiratory disease at more than one time point. Results in the first to cases did not change substantially; in the third exclusive cigarette use was no longer statistically significant, but the effect size was similar as in the main analysis.
FDA is now investing considerable effort on how to “educate” people about the “continuum of risk” and products that may be less risky than smoking. This study suggests that the difference in risk of e-cigarettes is not all that different from cigarettes. FDA needs to pause this effort while they consider what the science actually says about how broad that continuum is.
The Importance of Dual Use
The observed dual use risk of 2.70 is very close to the product of the separate risks of e-cigarettes and cigarettes, 1.49 x 1.85 = 2.76, indicating the using e-cigarettes impose separate independent risks. (We found the same thing in our earlier studies of e-cigarettes and heart attacks and respiratory disease.) As the authors note, this finding that dual use is more dangerous than either product alone is important because dual use is common, even among youth.
It also reinforces the importance of reporting ongoing dual use in studies of the effect of e-cigarettes on stopping cigarettes, since more people given e-cigarettes become dual users than stop smoking.
This study also adds to the case than FDA and other regulators need to account for dual use in their analyses of whether new tobacco products are “appropriate for the protection of public health.” Given how dangerous dual use is, it could swamp any hypothetical benefits of “switching completely.” While the authors didn’t explicitly make this point, this paper also found no significant difference in e-cigarette risks compared to cigarettes. So, switching completely may not confer benefit even without considering dual use.
Here is the abstract:
Introduction: Electronic nicotine delivery system (ENDS) use is highly prevalent among U.S. youth, and there is concern about its respiratory health effects. However, evidence from nationally representative longitudinal data is limited.
Methods: Using youth data (ages 12-17) from waves 1-5 (2013-2019) of the Population Assessment of Tobacco and Health (PATH) Study, multilevel Poisson regression models were estimated to examine the association between ENDS use, cigarettes, and diagnosed bronchitis, pneumonia, or chronic cough. Current product use was lagged by one wave and categorized as: (a) never/non-current use; (b) exclusive cigarette use; (c) exclusive ENDS use; and (d) dual ENDS/cigarette use. Multivariable models adjusted for age, sex, race and ethnicity, parental educational, asthma, body mass index, cannabis use, secondhand smoke exposure, and household use of combustible products. Data analysis was conducted in 2022-2023.
Results: 7.4% of respondents were diagnosed with bronchitis, pneumonia, or chronic cough at follow-up. In the multivariable model, exclusive cigarette use (IRR = 1.85; 95% CI 1.29-2.65), exclusive ENDS use (IRR = 1.49; 95% CI 1.06-2.08), and dual use (IRR = 2.70, 95% CI 1.61-3.50) were associated with a higher risk of diagnosed bronchitis, pneumonia, or chronic cough, compared to never/non-current use.
Conclusions: These results suggest that ENDS and cigarettes, used exclusively or jointly, increased the risk of diagnosed bronchitis, pneumonia, or chronic cough among U.S. youth. However, dual use was associated with the highest risk. Targeted policies aimed at continuing to reduce cigarette smoking and ENDS use among youth, especially among those with dual use, are needed.
The full citation is: Mukerjee R, Hirschtick JL, Arciniega LZ, Xie Y, Barnes G, Arenberg D, Levy DT, Meza R, Fleischer NL, Cook S. ENDS, cigarettes, and respiratory illness: Longitudinal associations among US youth. Am J Prev Med. 2023 Dec 9:S0749-3797(23)00503-2. doi: 10.1016/j.amepre.2023.12.005. Epub ahead of print. PMID: 38081374. It is available here.
Stanton Glantz blog 