Overview of data
The Global Adult Tobacco Survey (GATS) is the global standard for monitoring adult tobacco use in a systematic way which tracks key indicators of tobacco control. GATS surveys a nationally representative cross-sectional household based adult samples, aged 15 years and more, using a standard core questionnaire, sample design, and data collection and management procedures for each country. In India, GATS 1 surveyed 29 states and two Union Territories while GATS 2 surveyed 30 states and two Union Territories covering 69,296 & 74,037 individuals respectively. Stratified multi-stage cluster sampling design was used to identify the specific households for GATS survey. Each state and within each state, rural and urban areas were selected separately for sampling. Primary sampling Unit (PSU) comprised of wards in urban areas which were selected by a three-stage process. During the first stage, a checklist of all wards of towns and cities of each state were obtained which formed the sampling frame. Wards, required for sample, were selected by probability proportional to size (PPS) sampling method. In the next stage, a list of all census enumeration blocks (CEB) were obtained from which one CEB per selected ward was chosen by PPS. In the third stage, required number of residential households were selected from each CEB. In rural areas, households were selected through a two-stage sampling process where villages were PSU, selected through PPS. In the second stage, required number of households were selected from each village.
Amongst the enrolled households, Household Questionnaire was administered to determine the GATS eligibility requirements and to make a list of all eligible residents of the household. Further, one adult was randomly selected from each household to complete the individual questionnaire. The Individual Questionnaire contained questions about individual characteristics; smokeless tobacco use; smoking tobacco and cessation; secondhand smoke; tobacco-economics; media; and knowledge, attitudes, and perceptions about tobacco. The detailed methodology for GATS 1 and GATS 2 are published elsewhere [19, 20].
For this study, data was obtained from the website of Centers for Disease Control and Prevention, Atlanta. The data is open access available under the name of Global Tobacco Surveillance System DATA (GTSS Data) which was downloaded after registering with the website.
Adult females aged 15 years and above from the GATS 1 and GATS 2 formed the participants for this study. Available data of all females from both the rounds of GATS were analyzed for this study.
In GATS 1, 35,529 female participants were surveyed whereas a total of 40,265 females participated in the GATS 2 which formed the sample for this study.
The main outcome variable for analysis was smokeless tobacco use. Smokeless tobacco users (SLT Users) and smokeless tobacco non users (SLT Non users) have been classified based on the question “Do you currently use smokeless tobacco on a daily basis, less than daily, or not at all?”. All the participants who answered SLT use to be ‘daily’ or ‘less than daily’ were classified under SLT users and participants who replied as ‘not at all’ were listed as SLT Non users.
In this study, relationship of smokeless tobacco was assessed with the following independent variables: age, residential area (urban/rural), regions of the country (North, Central, East, North-East and West), educational qualification, occupation, wealth index and smoking tobacco (Yes/No). Age was grouped into four categories 15 to 30 years, 31 to 45 years, 46 to 60 years and more than 60 years. Education was stratified into five categories as those were illiterate (no formal education); incomplete primary school education; completed primary education but not secondary school formed by incorporating “primary school completed” and “less than secondary school completed” from original data; secondary and higher secondary formed by secondary and higher secondary school completed; and graduation and above by merging “college/university completed” and “post graduate degree completed”. Further, occupation was classified into six group, the first being government and non-government employees formed by merging the government employees and non-government employees as per the original data followed by Daily wage/ casual laborer. Separate data was not available for daily wage/ casual laborer group in the GATS 1 survey hence, daily wage/ casual laborer group was included only for GATS 2 analysis in this study. The further categories under occupation formed were self-employed, student, homemaker and unemployed which was formed by clubbing retired, unemployed but able to work and unemployed but unable to work.
All participants smoking daily or less than daily were grouped as smokers whereas participants who do not smoke at all were clubbed as non-smokers for the analysis. Wealth index was analyzed using Principal Component Analysis based on the possession of household assets through GATS India data. Based on the scores of component analysis, all households were divided into five quintiles. Further, quintile with the highest scores were categorized as rich class, quintile with minimum scores as poor class and the middle three strata as middle class. We took middle class to be more as they represent in the population.
Further, we also analyzed regional variations in the number of women who are willing to quit and attempted to quit SLT. For “willing to quit”, we combined all participants who responded that they want to quit within next month or within next 12 months or quit someday, but not within next 12 months and all those who responded that they were not willing to quit as “not willing to quit”. For attempted to quit, we categorized “During the past 12 months, have you tried to stop using smokeless tobacco?” with ‘yes’ as attempted and ‘no’ as not attempted.
Data were analyzed using STATA version 16.0 (STATA Corp., Texas) and R software (version 4.1.0) for graphs. Mean and Standard Deviation represents the measures of central tendency and dispersion for age. Frequency and proportion (%) for types of SLT used, socio-demographic characteristics of the participants with their exposure to SLT, are reported. Chi-square test was used to measure the significance between prevalence of GATS-1 and GATS-2. Correlates of SLT exposure were assessed separately using binary logistic regression. The variables which had p < 0.1 were included in the multivariable logistic regression analysis. We analyzed independent risk factor for all covariates and considered each covariate in regression model. Further, GATS 1 & 2 data were analyzed separately to calculate and compare Odds Ratio (Strength of Association) for each covariate separately. The association is expressed as Adjusted Odds ratio with 95% confidence interval (CI). Sampling weights were considered during analysis for both descriptive and regression models. For all weighted proportions, we added CI as the measure of uncertainty.
This study is based on secondary data obtained from GATS 1and GATS 2 and hence, there is no participant risk. The data used is properly acknowledged and referenced wherever required.