Cigarette Smoking Trajectories in Adult Former Smokers Using the JUUL System

Increased e-cigarette use prevalence is associated with decreased smoking prevalence among US adults

BACKGROUND

If US adults who smoke cigarettes are switching to e-cigarettes, the effect may be observable at the population level: smoking prevalence should decline as e-cigarette prevalence increases, especially in sub-populations with highest e-cigarette use. This study aimed to assess such effects in recent nationally-representative data.

METHODS

We updated a prior analysis with the latest available National Health Interview Survey data through 2022. Data were cross-sectional estimates of the yearly prevalence of smoking and e-cigarette use, respectively, among US adults and among specific age, race/ethnicity, and sex subpopulations. Non-linear models were fitted to observed smoking prevalence in the pre-e-cigarette era, with a range of 'cut-off' years explored (i.e., between when e-cigarettes were first introduced to when they became widely available). These trends were projected forward to predict what smoking prevalence would have been if pre-e-cigarette era trends had continued uninterrupted. The difference between actual and predicted smoking prevalence ('discrepancy') was compared to e-cigarette use prevalence in each year in the e-cigarette era to investigate whether the observed decline in smoking was statistically associated with e-cigarette use.

RESULTS

Observed smoking prevalence in the e-cigarette era was significantly lower than expected based on pre-e-cigarette era trends; these discrepancies in smoking prevalence grew as e-cigarette use prevalence increased, and were larger in subpopulations with higher e-cigarette use, especially younger adults aged 18-34. Results were robust to sensitivity tests varying the analysis design.

CONCLUSIONS

Population-level data continue to suggest that smoking prevalence has declined at an accelerated rate in the last decade in ways correlated with increased uptake of e-cigarette use.

Reply to Commentary on "Adult Smokers' Complete Switching Away from Cigarettes at 6, 9, and 12 Months After Initially Purchasing a JUUL e-Cigarette" and the Adult JUUL Switching and Smoking Trajectories (ADJUSST) Study

BACKGROUND

This is authors' reply to the Commentary on our publication entitled "Adult smokers' Complete Switching Away from Cigarettes at 6, 9, and 12 Months after Initially Purchasing a JUUL e-Cigarette."

METHODS AND RESULTS

Analyses addressed questions about follow-up rates and missed responses in the Adult JUUL Switching and Smoking Trajectories (ADJUSST) Study. Results demonstrate limited potential for selection bias, as participants who missed surveys were similar to those with complete data, and re-contact of participants who missed a follow-up indicated almost half were not smoking. Imputing smoking behavior for missing data would likely introduce bias and is not appropriate. The study demonstrated that JUUL products can facilitate high rates of complete switching away from cigarettes as suggested in previous experimental and observational studies. The ADJUSST cohort, including baseline nonsmokers, demonstrates a net reduction in smoking prevalence. Moreover, population modeling considering both benefits and harms demonstrated a net population benefit.

CONCLUSION

While the ADJUSST Study is not without limitations, the findings are consistent with multiple streams of real-world evidence that indicate that ENDS can facilitate switching among adults who smoke, and provide population benefits.

Population-level counterfactual trend modelling to examine the relationship between smoking prevalence and e-cigarette use among US adults

BACKGROUND

Studies have suggested that some US adult smokers are switching away from smoking to e-cigarette use. Nationally representative data may reflect such changes in smoking by assessing trends in cigarette and e-cigarette prevalence. The objective of this study is to assess whether and how much smoking prevalence differs from expectations since the introduction of e-cigarettes.

METHODS

Annual estimates of smoking and e-cigarette use in US adults varying in age, race/ethnicity, and sex were derived from the National Health Interview Survey. Regression models were fitted to smoking prevalence trends before e-cigarettes became widely available (1999-2009) and trends were extrapolated to 2019 (counterfactual model). Smoking prevalence discrepancies, defined as the difference between projected and actual smoking prevalence from 2010 to 2019, were calculated, to evaluate whether actual smoking prevalence differed from those expected from counterfactual projections. The correlation between smoking discrepancies and e-cigarette use prevalence was investigated.

RESULTS

Actual overall smoking prevalence from 2010 to 2019 was significantly lower than counterfactual predictions. The discrepancy was significantly larger as e-cigarette use prevalence increased. In subgroup analyses, discrepancies in smoking prevalence were more pronounced for cohorts with greater e-cigarette use prevalence, namely adults ages 18-34, adult males, and non-Hispanic White adults.

CONCLUSION

Population-level data suggest that smoking prevalence has dropped faster than expected, in ways correlated with increased e-cigarette use. This population movement has potential public health implications.