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.