A Cross-Sectional Study of Electronic Cigarette Use Among Chinese Adult Populations in Four Cities of China. Part I. Questionnaire Survey

Four cities were selected to launch the project, which were selected based on the Baidu search indices (24). Notably, these cities were the top four cities for EC usage in the period between October 2015 and October 2017. EC users were recruited both through online advertisements and EC experience stores.

In order to participate, volunteers must have an EC usage history for 3 months past with a frequency of at least 3 days per week. Moreover, participants were required to be over 18 years old, without serious cardiovascular or respiratory diseases, and they had to sign their informed consent prior to in-person interviews. The exclusion criteria included: a) illegal drugs abuse; b) major depressive disorders or other psychiatric disorders; c) severe cardiovascular diseases, chronic obstructive pulmonary disease, lung cancer or other diagnosed tumors, and severe physiological deformities. Women were excluded if they were breastfeeding or pregnant.

On the basis of multiple considerations, like extensive consultation with epidemiologic researchers, market salesmen, product researchers, and development personnel, a large number of studies were consulted. Based on previous studies, we designed our survey questionnaire for EC-using participants, which included the following elements: (i) Characteristics including age, gender, education, occupation and other information; (ii) Consumption behavior including duration of EC use, device type (cigarette-like: disposable and one-off use; tank: replacement of EC liquid cartridges and reusable batteries; customizer: refillable with e-liquids to supplement EC vapor), nicotine concentration, taste, usage frequency, priority factors; (iii) History and status of tobacco products, former daily use of traditional cigarettes, span of time in which traditional cigarettes were consumed, uptake or reduction of smoking after EC use; (iv) Perception and reasons for use, method of understanding, harm perception, smoking cessation, influence on surrounding people; (v) ECs influence on the users’ personal and family health, irritation of the mouth, changes in the respiratory tract, changes in physical health, and attitude of family and friends towards ECs.

The study was reviewed by and received ethics clearance from the Public Health Institute of the University of Zhengzhou. The participants’ voluntary informed consent, confidentiality, and good research practice were followed throughout the investigation. The data of the questionnaire survey was collected through in-person interviews. In detail, the photos, videos of EC devices, and information from volunteers were all collected at the interview site.

All analyses were conducted using SPSS 22.0 Demo software (SSPS Inc., Chicago, IL, USA). Continuous variables were defined as: “EC use times per day”, “Amount of liquid per day”. Data are expressed as mean ± SD. Quantitative data were analyzed by single factor ANOVA with the Levene test to test homogeneity of variance. When variance was homogeneous, the Bonferroni method was used for multiple comparisons of the mean of each group. If variance was uneven, Dunnett's T3 test was used for multiple comparisons. Chi-square analysis was used to examine differences in categorical variables, such as flavor preferences, nicotine concentrations, duration of EC use, using frequency during the past 30 days, and the proportion of the dual users who smoked cigarettes containing different concentrations of “tar” before and after using ECs.

Through the geographical distribution of the Baidu search index and the city ranking of the Baidu search index, four cities including Beijing, Shanghai, Guangzhou, and Shenzhen, were marked as high EC usage cities. In this study, 18,970 people were invited through internet shops and local EC stores. Ultimately 527 people met the research conditions, and 511 people participated in the survey. Among those who did not participate were many who were reluctant to engage in all requested procedures prior to the start. The final group consisted of 82, 123, 149, and 157 volunteers from Beijing, Shanghai, Guangzhou, and Shenzhen, respectively. The invitation/success rate of e-cigarette users was only 2.8%. The main factor affecting the success rate was the low popularity of e-cigarettes in China at the time.

The baseline sociodemographic characteristics of the participants are displayed in Table 1. EC users were disproportionately young, with 47.6% between 18 and 29 years old. The majority of EC users was male, with an overall ratio of 90.6%. Variance ratios based on gender suggest that the city of Shanghai had the largest percentage of women users among the four cities, which was about 15.4%. As to the participants’ education level, it was found that the proportion of participants with a bachelor degree, an associate degree, or high school graduation was 45.2%, 36.0% and 16.8%, respectively. According to the occupational distribution, the number of participants working in the general staff of a company and the middle or senior management were relatively higher than others, which were 28.4% and 23.3% respectively. 36.9% of the participants were students in Shenzhen. Figure 1 shows in more detail the differences in occupational distribution across cities and the total.

Figure 1

An investigation of the type of EC used in the four cities showed that the majority of users (n = 491, 96.1%) chose the cartomized device (shown in Table 2). Only 15 and 5 participants, respectively, chose the refillable tank device and disposable cigarette-like ECs. In the group of users of the customized device, age groups were used to analyze and compare consumer behaviors. Statistical analysis and distribution of group data determined that there was no difference in daily usage of ECs and EC liquid among all age groups (shown in Table 3).

Compared with the age groups of “18–29 years” and “30–39 years”, the amounts of liquid used per day in the age groups of “40–49 years” and “over 50 years” were lower (p < 0.01).

Flavor preferences were grouped into five categories: Fruit – fresh fruit such as bananas and apples (n = 294, 59.9%); tobacco (imitation CHUNGHWA, Furogwang, Yuxi, or similar) (n = 101, 20.6%); cigar flavor (n = 7, 1.4%); chocolate flavor (n = 5, 1.0%); menthol flavor (n = 62, 12.6%,); or other (flavors not readily classified by the above mentioned categories, such as fresh milk, Red Bull, ice cream, Coke, Yakult, or red wine) (n = 22, 4.5%). Most EC users surveyed were found to prefer fruit-flavored products. Flavor preference was observed to be further stratified by age group. The majority of participants in the age group of 18–29 years preferred fruit flavors (n = 173, 73.3%).

However, preference for fruit flavors decreased among the 30–39 year-old participants (n = 79, 48.2%). The concentration of nicotine was divided into 5 grades: nicotine-free; low: 1–5 mg/mL (0.1–0.5%); moderate: 6–11 mg/mL (0.6%–1.1%); high: 12–20 mg/mL (1.2%–2.0%); and > 20 mg/mL. A majority (n = 284, 57.8%) preferred low nicotine concentrations. Only one user reported a preference for an EC containing >20 mg/mL nicotine. EC use duration of the majority of users ranged from 6 months to 2 years (65.3%). Most participants (n = 313, 63.8%) used ECs every day, with no significant differences across all age groups in the usage frequency in the past 30 days. (Table 4).

Table 5 displays the current use of the different tobacco products. In Table 6 the term “Product usage” was individually separated into (i) users who only used ECs (n = 137, 26.8%), including non smokers and former smokers, (ii) users who simultaneously smoked conventional cigarettes (n = 374, 73.2%) termed as “dual use”. In the group of ECs-only use, 80.3% of the participants were cigarette smokers. This means that smoking may affect the use of e-cigarettes (Table 6). In the group of dual users, there were a lot of participants (88.2%) who previously smoked before starting to use ECs. It should also be noted that 11.8% of the participants never smoked before using ECs.

And Table 6 furthermore shows that some participants will smoke cigarettes after using ECs.

On average, after using an EC, 20.7% of conventional cigarette smokers attempted to quit smoking. Geographically, this value varied somewhat in Beijing (25.0%), Shanghai (19.4%), Guangzhou (17.4%), and Shenzhen (22.5%). Successful smoking cessation within one month was at 27.9%. And the time interval necessary for quitting smoking in different cities proved quite different. In Beijing, 43.8% of EC-using participants quit smoking within a month whereas 45.2 % of EC consumers of Shenzhen quit smoking within 3 months (Table 7).

Daily cigarette consumption of the dual users before and after using ECs are shown in Table 8. According to the data of the four cities and in total, the number of cigarettes smoked per day decreased significantly after the participants’ starting to use ECs. The use of e-cigarettes affected the choice of cigarettes smoked by dual users concerning “tar” content. After using e-cigarettes, the proportion of people smoking low “tar” cigarettes increased from 16.4% to 30.6% (Table 9). There was a significant increase in the number of dual users smoking cigarettes with “tar” yields below 6 mg (X² = 34.064, p < 0.001). The proportion of people smoking low “tar” cigarettes was the same in each city.

The reasons for initiating EC use were analyzed in Table 10. Some reasons for use initiation were reported as: “to quit smoking”, “to reduce smoke-related exposure to family members”, “to avoid smoking bans in public places”, “the choice of multiple flavors in ECs”, “to pursue fashion or curiosity”, “economic reasons”, “to make smoke rings”, “to pursue a healthy lifestyle”, or “living abroad for a long time”. Participants were permitted to provide more than one reason for use initiation. Most people stated that quitting smoking and reducing the exposure of family members to cigarette smoke were their most important reasons for starting EC use. The proportions were 74.8% and 49.9% respectively. 69.5% of the participants came into contact with ECs through relatives, friends, or colleagues for the first time. Other ways to get to know e-cigarettes are traditional advertising, articles, online advertisements, EC experience stores or shops, and WeChat circles. More than half of the participating EC users (51.3%) believe there is no harm at all in ECs although 9.4% participants thought ECs are less harmful than traditional cigarettes. But 88.6% of the participants were unsure whether ECs were less harmful than cigarettes. A majority of participants (60.5%) considered that using ECs could help to quit smoking and them using ECs began as a way to stop smoking cigarettes. When using ECs in public places, 46.8% of the users thought that it would not cause health impacts on the surrounding non-smokers through second-hand vaping. But 31.0% of the participants considered that using ECs may affect nearby non-smokers. Participants stated that they gained information on health effects of ECs from different sources: by consulting professional books or scientific literature (28.4%), from the internet (27.3%), or from information provided by acquaintances (29.8%). The majority of the participants (62.7%) expressed an openness to communicate frequently with others about the products, flavors, usage, and related information.

As shown in Table 11, a small number of participants experienced side effects. Reported side effects included: irritation to the mouth (21.5%) and adverse respiratory effects (56.6%). After using ECs for 3 months, 42.3% of the participants felt better about their overall health as defined by factors such as: weight, sleep quality, memory, or sense of smell. Simultaneously 50.5% of the participants claimed that their family and friends supported their use of ECs.