Table 1:

E-cigarette Disease epidemiology

Design/Location, Year^ref	Patient population, No.	Findings
Respiratory Symptoms and Disease
Asthma
Cross-sectional analysis/South Korea, 2016¹⁸	N = 35,904 high school students	Prevalence rates of asthmatics was 3.9% in current e-cigarette users, 2.2% in ‘former e-cigarette users’, and 1.7% in ‘never e-cigarette users’. The AOR for asthma for ‘current e-cigarette’ users was 3.41 (95% CI: 1.79–6.49).
Cross-Sectional analysis/US, 2019¹⁹	N = 402,822 never combustible cigarette smoker adults (> 18 years old) Current e-cigarette users, 3,103 (0.8%). 8.5% had asthma Median age group of current e-cigarette users was 18–24 years	Current e-cigarette use was associated with higher odds of self-reported asthma compared to never e- cigarette users (OR= 1.39; 95% CI: 1.15–1.68).
Chronic Bronchitis (chronic cough, phlegm, wheeze or bronchitis)
Cross-sectional study/California, US, 2017²⁰	N = 2,086 youth (11^th and 12^th grade)	Risk of bronchitic symptoms was higher among past users (OR= 1.85; 95% CI: 1.37–2.49), and current users (OR= 2.02; 95% CI; 1.42–2.88), compared with never-users,
Cross-Sectional analysis/Hawaii, US, 2019²¹	N = 8,087, mean age 55 years old	E-cigarette use was associated with chronic pulmonary disorder (AOR= 2.58; 95% CI 1.36–4.89, p<0.01).
Other respiratory symptoms
Longitudinal analysis/US, 2020²²	N = 46,000 ages 12 and older	Associations between former e-cigarette use (AOR= 1.31; 95% CI: 1.07–1.60) or current e-cigarette use (AOR= 1.29; 95% CI: 1.03–1.61) and respiratory disease. Current combustible tobacco smoking (AOR= 2.56; 95% CI: 1.92–3.41) was also associated with having respiratory disease.
Cross-sectional study/US, 2020²⁴	N = 28,171 adults, 641 (1.2%) current exclusive e-cigarette users, 8525 (16.6%) were current exclusive smokers, 1106 (2.0%) were dual users, 17 899 (80.2%) were nonusers	Incidence of wheezing and related respiratory symptoms was higher in current e-cigarette users (AOR= 1.67; 95% CI: 1.23–2.15) compared with nonusers. Current e-cigarette users had lower risk of wheezing and related respiratory symptoms compared with current smokers (AOR= 0.68; 95% CI: 0.53–0.87).
Cardiovascular Disease
Cross-sectional analysis/US, 2018²⁵	N = 69,725 adults (>18 years)	Daily e-cigarette use was independently associated with higher odds of having had a myocardial infarction (OR= 1.79; 95% CI: 1.20–2.66, p=0.004) as was daily conventional cigarette smoking (OR= 2.72; 95% CI: 2.29–3.24).
Cross-sectional analysis/US, 2019²⁶	N = 449,092 adults (>18 years)	No association between e-cigarette use and cardiovascular disease. Dual use was significantly associated with higher rates of cardiovascular disease vs smoking alone (OR = 1.35; 95% CI: 1.18–1.56).

Table Legend: OR = odds ratio, AOR = adjusted odds ratio, CI = confidence interval