E-cigarette use and prevalence of lung diseases among the U.S. population: a NHANES survey

The primary aim of this study was to evaluate epidemiological characteristics and prevalence of lung disease among e-cigarettes users in the United States. A population-based, cross-sectional survey was performed using the National Health and Nutrition Examination Survey (NHANES) of 2015-2018. Adults using e-cigarettes (SMQ900), traditional smoking (SMQ020: > 100 cigarettes in lifetime or SMQ040: current cigarettes use), and dual smoking (e-cigarettes and traditional smoking) were identified and compared in their sociodemographic characteristics and prevalence of lung diseases (Asthma: MCQ010 and COPD: MCQ160O). We used the chi square test (categorical variables) and Mann-Whitney test and unpaired-student t test (continuous variables). p-value <0.05 was used as a reference. We excluded respondents <18 years and missing data on demographics and outcomes. Out of 178,157 respondents, 7745 (4.35%), 48,570 (27.26%), and 23,444 (13.16%) were e-cigarette smokers, traditional smokers, and dual smokers, respectively. Overall prevalence of asthma was 15.16% and COPD was 4.26%. E-cigarette smokers were younger in comparison to traditional smokers (median: 25 years vs 62 years; p < 0.0001). In females (49.34% vs 37.97%), Mexican (19.82% vs 13.35%), annual household income above $100,000 (23.97% vs 15.56%), prevalence of e-cigarette smoking was higher in comparison to traditional smoking (p < 0.0001). The prevalence of COPD was higher among dual smokers in comparison to e-cigarette and traditional smoking (10.14% vs 0.25% vs 8.11%; p < 0.0001). Prevalence of asthma was higher among dual and e-cigarette smokers in comparison with traditional smokers and non-smokers (22.44% vs 21.10% vs 14.46% vs 13.30%; p < 0.0001). Median age (Q1-Q3) was lower at which asthma (7 years (4-12) vs 25 years (8-50)) was diagnosed first among e-cigarettes smokers in comparison with traditional smokers. In a mixed effect multivariable logistic regression analysis, we found higher odds of asthma among e-cigarette users in comparison with non-smokers (Odds ratio (OR): 1.47; 95% Confidence Interval (CI): 1.21-1.78; p = 0.0001). Chronic Obstructive Pulmonary Disease (COPD) respondents were also associated with 11.28 higher odds of e-cigarette utilization (Oddsratio (OR): 11.28; 95% Confidence Interval (CI): 5.59-22.72; p < 0.0001). We conclude the higher prevalence of e-cigarette users is seen among the younger population, female, Mexican race, and annual income above $100,000 in comparison to traditional smokers. Chronic Obstructive Pulmonary Disease (COPD) and asthma were both more prevalent in dual smokers. As asthma was more prevalent and diagnosed at an early age in e-cigarette smokers, more prospective studies are needed to understand the effects of e-cigarette among the population at risk to mitigate the sudden rise in utilization and to create awareness.