Explaining social group disparities in ever tobacco use among women aged 45 years and older in India: a nonlinear decomposition analysis

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Social group differences in tobacco use among Indian women are well documented; however, most existing studies remain descriptive, reporting associations without explaining disparities in ever tobacco use between Scheduled Caste/Scheduled Tribe (SC/ST) and non-SC/ST women. This study examines the SC/ST–non-SC/ST gap in ever tobacco use among women aged 45 years and older in India by decomposing it into explained and unexplained components.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Using Longitudinal Ageing Study in India (LASI, 2017–18) data on women aged ≥ 45 years, we analysed ever tobacco use, defined as ever use of any smoked or smokeless tobacco product. A multivariable logistic regression model was fitted to estimate associations between social group (SC/ST vs. non-SC/ST) and ever tobacco use, adjusting for demographic, socioeconomic, and spatial characteristics. Fairlie decomposition was applied to partition the SC/ST–non-SC/ST gap into explained and unexplained components.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Ever tobacco use was higher among SC/ST women than among non-SC/ST women (26.4% vs. 16.0%). In adjusted logistic regression models, SC/ST women had significantly higher odds of ever tobacco use compared with non-SC/ST women (adjusted odds ratio [AOR]: 1.30, 95% confidence interval (CI): 1.17–1.43). Fairlie decomposition showed that 75.6% of the SC/ST–non-SC/ST gap in ever tobacco use was explained by differences in observed characteristics. Level of educational attainment (28.8%), occupational history (24.2%), and state/region of residence (40.2%) were the largest contributors to the explained component. Approximately 24.4% of the disparity remained unexplained, indicating that measured socioeconomic and spatial characteristics did not fully account for the SC/ST–non-SC/ST gap.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>The findings show that the SC/ST–non-SC/ST gap in ever use of tobacco is closely linked to social and geographical disadvantage, especially differences in education, work, rural residence, and state context. Tobacco-control efforts should therefore pay greater attention to women aged 45 years and older from socially disadvantaged groups and high-prevalence settings.</jats:p> </jats:sec>