Electronic Nicotine Delivery Systems (ENDS) use during a five-year period is not associated with self-reported chronic obstructive pulmonary disease (COPD) after adjustment of cigarette smoking history: A longitudinal analysis of PATH data

Abstract

Background: Understanding the relationship between electronic nicotine delivery systems (ENDS) use and chronic obstructive pulmonary disease (COPD) and other respiratory conditions is critical. However, previous studies have not adequately controlled for history of cigarette smoking. Research Question: To examine the prospective association between ENDS use and self-reported incident COPD after adjusting for cigarette smoking history. Study Design and Methods: Using waves 1-5 of the US Population Assessment of Tobacco and Health (PATH) study, we examined the association between ENDS use and self-reported incident COPD among adults aged 40+ using discrete time survival models. Current ENDS use was measured as a time-varying covariate, lagged by one wave, defined as established daily or some days use. We controlled for baseline demographics (age, sex, race/ethnicity, education), health characteristics (asthma, obesity, exposure to second-hand smoke), and smoking history (smoking status and cigarette pack-years). Results: Incident COPD was self-reported by 925 respondents during the five-year follow-up period. Prior to adjusting for other covariates, time-varying ENDS use appeared to nearly double the risk of incident COPD (HR 1.98, 95% CI 1.44-2.74). However, ENDS use was no longer significantly associated with COPD (aHR 1.10, 95% CI 0.78-1.57) after adjusting for current cigarette smoking and cigarette pack-years. The risk of self-reported incident COPD increased with cigarette pack-years and was higher for respondents who were older, female, less educated, and had baseline asthma or obesity. Interpretation: ENDS use did not significantly increase the risk of self-reported incident COPD over a five-year period once current smoking status and cigarette pack-years were taken into account. Cigarette pack-years, on the other hand, remained associated with a net increase in the risk of self-reported incident COPD. These findings highlight the importance of using prospective longitudinal data and properly controlling for cigarette smoking history to assess the independent health effects of ENDS.