Table 1. General characteristics of the study participants according to electronic cigarette use.
| Total (N = 10,692) | Never use (n = 9,905) | Ever use (n = 609) | Current use (n = 178) | P-value | |
|---|---|---|---|---|---|
| Age (years), mean (SE) | 46.9 (0.3) | 48.1(0.3) | 36.6(0.5) | 36.2(1.0) | <0.001*† |
| Sex, %(SE) | <0.001*† | ||||
| Male | 51.0 (0.5) | 46.9 (0.5) | 90.3 (1.3) | 87.0 (2.6) | |
| Female | 49.0 (0.5) | 53.1 (0.5) | 9.7 (1.3) | 13.0 (2.6) | |
| Residential area, % (SE) | 0.631 | ||||
| Urban | 84.8 (1.7) | 84.6 (1.7) | 86.2 (2.5) | 86.0 (3.2) | |
| Rural | 15.2 (1.7) | 15.4 (1.7) | 13.8 (2.5) | 14.0 (3.2) | |
| Education, % (SE) | <0.001*† | ||||
| Middle school | 14.6 (0.6) | 15.8 (0.6) | 3.7 (0.7) | 3.1 (1.1) | |
| High school | 9.1 (0.4) | 9.5 (0.4) | 5.3 (0.9) | 3.0 (1.3) | |
| College or higher | 34.6 (0.7) | 33.3 (0.7) | 45.7 (2.3) | 49.5 (4.3) | |
| Unanswered | 41.7 (1.0) | 41.3 (1.0) | 45.3 (2.3) | 44.4 (4.3) | |
| Smoking status | <0.001*†‡ | ||||
| None | 62.0 (0.7) | 67.9 (0.7) | 9.0 (1.2) | 1.1 (0.8) | |
| Passive | 12.2 (0.4) | 13.2 (0.5) | 3.9 (0.8) | 1.6 (1.0) | |
| Active | 25.8 (0.6) | 18.9 (0.6) | 87.1 (1.5) | 97.4 (1.2) | |
| Alcohol consumption, % (SE) a | <0.001*† | ||||
| <1/week | 77.7 (0.5) | 80.2 (0.5) | 54.0 (2.5) | 56.5 (4.1) | |
| ≥1/week | 22.3 (0.5) | 19.8 (0.5) | 46.0 (2.5) | 43.5 (4.1) | |
| Physical activity, % (SE) b | 0.426 | ||||
| No | 52.5 (0.7) | 52.7 (0.8) | 50.5 (2.4) | 48.8 (4.0) | |
| Yes | 47.5 (0.7) | 47.3 (0.8) | 49.5 (2.4) | 51.2 (4.0) | |
| Body mass index (kg/m2), % (SE) | <0.001*† | ||||
| <23.0 | 41.7 (0.6) | 42.8 (0.7) | 32.4 (2.0) | 29.2 (3.8) | |
| 23–24.9 | 22.9 (0.5) | 23.0 (0.5) | 22.6 (1.9) | 20.5 (3.1) | |
| ≥25 | 35.4 (0.6) | 34.2 (0.6) | 45.0 (2.3) | 50.3 (4.1) | |
| Systolic blood pressure, mmHg | 117.7 (0.2) | 117.8 (0.3) | 116.4 (0.6) | 116.0 (0.9) | 0.007* |
| Diastolic blood pressure, mmHg | 76.0 (0.2) | 75.8 (0.2) | 77.8 (0.4) | 77.3 (0.7) | <0.001* |
| Glomerular filtration rate (GFR), mL/min/1.73m2 | 97.1 (0.3) | 96.4 (0.3) | 102.6 (0.6) | 104.5 (1.3) | <0.001*† |
| High-sensitivity C-reactive protein (HS-CRP), ng/mL | 1.18 (0.0) | 1.16 (0.0) | 1.28 (0.1) | 1.40 (0.2) | 0.219 |
| Median HS-CRP, ng/mL | 0.56 | 0.54 | 0.60 | 0.64 | |
| Inter-quantile range | 0.36–1.07 | 0.35–1.06 | 0.40–1.20 | 0.40–1.15 |
Data were presented as weighted percentages (standard error [SE]) or weighted means (SE) unless otherwise stated.
P-values calculated by Chi-square tests for categorical variables, Student’s t-tests for continuous variables, and Mann–Whitney U-tests for non-normally distributed variables.
Three post-hoc analyses with Bonferroni correction were performed, with P <0.017 considered significantly;
*Never vs. Ever,
†Never vs. Current,
‡Ever vs. Current.
Smoking status was categorized from self-report and urinary cotinine level (>5 ng/dL for passive smokers and >50ng/dL for active smokers).
a Alcohol consumption was defined as ≥7 drinks in men and ≥5 drinks in women per occasion.
b Physical activity was defined as ≥150 min of moderate activity per day or ≥75 min of vigorous activity per day based on World Health Organization (WHO) recommendations.