E-cigarette use among adults in China: findings from repeated cross-sectional surveys in 2015–16 and 2018–19

The use of e-cigarettes among adults is increasing globally. Since 2018, policies in China have restricted e-cigarette use; however, little information is available on the national trend in e-cigarette use before regulations were implemented. Therefore, we sought to estimate the trend in e-cigarette use in China before policy implementation and explored associated factors.We assessed two nationally representative cross-sectional datasets from the China Chronic Disease and Nutrition Surveillance (CCDNS) surveys initiated in 2015 (June, 2015, to May, 2016) and 2018 (August, 2018, to June, 2019). The surveys were done at 298 national disease surveillance points in 31 provinces in mainland China, and used a multistage, stratified, cluster-randomised sampling design, recruiting community-based Chinese adults aged 18 years and older. Within the standard CCDNS survey, face-to-face questionnaire interviews were used to collect self-report data on e-cigarette use in the preceding 30 days. E-cigarette users were those who self-reported e-cigarette use on 1 day or more in the past 30 days. Prevalence estimates of past 30-day e-cigarette use were weighted to represent the Chinese adult population accounting for the complex sampling design. Populations for the years 2015-16 and 2018-19 were standardised with the 2010 population census to gain comparable estimates. Multivariable logistic regression models adjusted for age, sex, urban or rural residence, household income, occupation, and education level were applied to identify factors associated with the likelihood of e-cigarette use among the total population, ever smokers (current and former), and never smokers across both surveys.Our study included 189 306 Chinese adults from the 2015 survey (100 405 [53·0%] women; mean age 43·6 years [SD 14·6]) and 184 475 Chinese adults from the 2018 survey (102 373 [55·5%] women; mean age 43·4 years [13·9]). The weighted prevalence of past 30-day e-cigarette use among Chinese adults increased from 1·3% (95% CI 1·1-1·5%) in 2015-16 to 1·6% (95% CI 1·4-1·8%) in 2018-19 (an increase of 0·3% [95% CI 0·1-0·6]; Rao-Scott χ2 p=0·0086). Based on weighted proportion data, e-cigarette users were predominantly men (97·4% [95% CI 96·7-98·1] in 2015-16 and 97·0% [95·4-98·6] in 2018-19) and current conventional smokers (93·0% [90·7-95·2] in 2015-16 and 96·2% [95·1-97·3] in 2018-19). Across both surveys, the odds of e-cigarette use were significantly associated with obesity (odds ratio 1·6 [95% CI 1·3-2·1]; p=0·0007), awareness of smoking hazards (1·2 [1·0-1·4]; p=0·022), and smoking status (in current smokers, 135·2 [87·7-208·6]; and in former smokers, 33·5 [21·3-52·7]; p<0·0001). Among current smokers, the odds were increased with daily cigarette consumption (2·1 [1·5-2·8]; p<0·0001), smoking more than 20 cigarettes per day (1·8 [1·5-2·3]; p<0·0001), and an attempt to quit smoking (within the past 12 months, 1·9 [1·5-2·4]; and before the past 12 months, 1·5 [1·3-1·9]; p<0·0001). In never smokers, the odds were increased in those aware of the hazards of smoking (2·4 [1·2-4·7]; p=0·011).E-cigarette use in China remains low but has increased substantially between 2015 and 2019. Our study identified increased e-cigarette use among subpopulations, and use patterns, that warrant further attention from public health policy makers in China.Chinese Central Government, National Key Research and Development Program of China.