Socioeconomic inequality in any tobacco use versus current smoking across 66 DHS countries: Indirect implications for smokeless tobacco and oral cancer prevention.

INTRODUCTION: Smokeless tobacco use is a major preventable risk factor for lip and oral cavity cancer, with a particularly heavy burden in South and Southeast Asia. We aimed to quantify, across countries, whether the socioeconomic gradient of any tobacco use is more pro-poor than that of smoked tobacco alone, thereby indirectly assessing the additional inequality attributable to smokeless tobacco. METHODS: In this secondary analysis of publicly available Demographic and Health Surveys (DHS) data (66 countries, survey years 1999-2024), supplemented by the WHO Global Health Observatory and World Bank indicators, we computed concentration indices (CIXs), the slope index of inequality (SII), and Wagstaff-normalized CIXs for smoking and any tobacco use across wealth, education level, and residence dimensions. Eligible observations were country-survey estimates stratified by wealth quintile, education level, or urban/rural residence, with complete data across all subgroups; national-total, age-, and region-only estimates were excluded. The core hypothesis was tested indirectly, via paired comparison of any-tobacco versus smoked-only CIXs (81 paired observations), because DHS smokeless indicators are available only as national aggregates. Wagstaff decomposition quantified the relative contributions of socioeconomic determinants. RESULTS: The mean wealth-related CIX for smoking was -0.045 (SD=0.184), with 66% of estimates negative. The mean CIX for any tobacco use (-0.094) was significantly lower than for smoking alone (-0.060; paired ΔCIX= -0.033, 95% CI: -0.060 - -0.007, p=0.017), with 62% of pairs showing a more pro-poor gradient for any tobacco use. Education level and residence together accounted for >80% of explainable inequality in the decomposition analysis. CONCLUSIONS: The socioeconomic gradient of any tobacco use is significantly more pro-poor than that of smoking alone, suggesting that smokeless tobacco amplifies tobacco-related health inequality. These ecological findings suggest that tobacco-control monitoring may benefit from integrating smokeless tobacco into inequality surveillance; individual-level studies are needed before specific populations are targeted.