Association between Perceived Smoking Harms and Intention to Quit: A Cross-sectional Analysis of the Global Adult Tobacco Survey in Vietnam | BMC Public Health
Source of data and study population
Data were obtained from the 2015 Vietnam Global Adult Tobacco Survey (GATS), which is a nationally representative cross-sectional survey of 8,996 Vietnamese participants aged ≥15 years. Standardized approaches to sampling method, questionnaire design, data collection, data management, and ethical considerations were used for the conduct of GATS. The questionnaire covered 10 sections related to the World Health Organization’s MPOWER measures to help countries combat tobacco use: (1) demographic characteristics, (2) smoking, (3) e-cigarette use, (4 ) smokeless tobacco use, (5) cessation efforts, (6) second-hand smoke exposure, (7) economics, (8) media exposure, (9) knowledge, attitudes and perceptions, and (10) pictorial health warnings and tax stamps on cigarette packs.
Tobacco users were defined as those who reported currently smoking any type of tobacco (eg, cigarette, bamboo waterpipe, smokeless tobacco, etc.) daily or less than once per day. After excluding non-smokers and occasional smokers, women, and people under the age of 18, 1,600 adult male smokers were available for inclusion in this study. We excluded non-daily smokers due to the lack of several information on smoking behaviors such as first use of a cigarette/waterpipe after waking up among non-daily smokers, which was a well-known factor (c i.e. nicotine addiction) associated with the intention to quit. After excluding 18 smokers who consumed these other minor types of tobacco products (shisha, smokeless tobacco, e-cigarettes and cigars) and 231 users who had incomplete information on the relevant variables, 1,351 smokers were included in the study. final analysis, including 966 cigarette-only users, 256 bamboo waterpipe-only users, and 129 dual users (Fig. 1).
Description of variables
The main outcome of this study is the intention to quit smoking. All smokers who planned to quit ‘within the next month’, ‘within the next 12 months’ or ‘someday but not within the next 12 months’ were classified as intending to quit. Those who responded “not interested in quitting” were classified as not intending to quit, which was also defined in a previous study .
Perceived harms from tobacco use were independent variables, including knowledge of whether cigarette and waterpipe use cause serious illness (both do not cause serious illness, only waterpipes cause serious illness, only cigarettes cause serious illness, or both cause serious illness), and perceived harms of waterpipe use compared to smoking (less harmful, equally harmful or more harmful).
For the covariates, the groups of factors associated with the intention to quit smoking have been illustrated in the conceptual diagram in Fig. 2. At the individual level, demographic characteristics included age (18-24, 25-44, 45-65, or ≥ 65), ethnic group (Kinh-major ethnicity, or other-minor ethnicities such as Thai, Tay , Nung, Dao, etc.), residential area (rural or urban), level of education (elementary school or less, secondary school, high school or more), marital status (single, married or separated, divorced or widowed). Occupations were categorized into professionals or managers (eg, legislators, senior civil servants or managers; highly skilled professionals; or technicians or associated professionals), skilled workers (eg, members of the armed forces; service workers; shop assistants and markets; skilled farmers). and fish workers; craftsmen and workers in related trades; or plant and machine operators and assemblers), semi-skilled laborers or clerks (eg, elementary tradesman, clerks, drivers, or janitors), and others (eg, student, homemaker, retired, or unemployed).
Information on smoking-related behaviors, including the type of tobacco products used (cigarettes, waterpipe, or dual user) and age at initiation to tobacco use were obtained. Among daily tobacco users, the number of cigarettes smoked and waterpipe sessions per day were asked for cigarette smokers and waterpipe users, respectively. Time to first cigarette or pipe tobacco use after awakening (≤ 5, 6–30, 31–60, or > 60 min) was determined.
At the household level, information on the number of family members, having children at home (yes or no) and the regulation of tobacco use at home (no ban, ban partial or complete ban) have been obtained. No household smoking ban has been set as smoking is allowed in all rooms inside the house or there are no rules about no smoking. Partial ban has been defined as smoking is allowed in certain rooms inside the house or smoking is generally not allowed inside your home, but there are exceptions. Smoking is never allowed inside the house was a complete ban.
For community factors, tobacco control policy was also measured. Data were also recorded on whether exposure to pictorial health warnings on cigarette packs, anti-smoking campaigns or information encouraging people to quit smoking, and advertisements or signs to promote tobacco products in the past 30 days in places such as newspapers, television, radio, or the Internet.
The frequency distribution for each variable by intention to quit was performed and the collinearity of the variables was assessed. Multiple logistic regression analysis was used to assess the association between intention to quit smoking and perceived harm to cigarette and bamboo waterpipe tobacco. The final model was selected after considering collinearity of individual-level factor variables, adjustment for potential confounding factors, including individual-level factors (age group, education level, state marital status), age at onset of smoking, number of cigarette/waterpipe sessions used per day, time to first cigarette or pipe tobacco use after waking up), household-level factors (no smoking at home, having children at home) and community level factors (exposure to anti-smoking campaigns or encouragement to quit, and exposure to advertisements/signs to promote tobacco products during past 30 days), and model fit assessment. Due to the lack of standardized measurement of cigarette and waterpipe intensity, the number of cigarettes smoked and the number of waterpipe sessions used daily for cigarette users and waterpipe users water were measured, respectively. Therefore, we combined two of these variables into one to fit the multiple logistic regression model among the entire study population. A subgroup analysis stratified by tobacco users was performed and the reference group of a variable on the perceived harm of waterpipe versus cigarette smoking was changed. For cigarette users only, the perceived harms of smoking versus waterpipe smoking were asked; in contrast, for waterpipe users only, the perceived harm of waterpipe use relative to smoking was measured. To examine the selection bias due to the exclusion of 231 observations with missing information on the variables concerned, we carried out the sensitivity analysis of the factors associated with the intention to quit by the groups of tobacco users, presented in Supplementary Table 1. Descriptive and analytical statistical approaches were applied using weights. . All statistical analyzes were performed with STATA software (version 14.0) and the values of p