ArticlePloS one2026
The Healthy Smoker Paradox: Socioeconomic status as a fundamental cause of reversed anemia risk among Yemeni youth.
Article in PloS one, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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Abstract
backgroundWhile tobacco smoking biologically elevates hemoglobin through chronic hypoxia, this study investigates an unexpected paradoxical reversal in conflict-affected Yemen, testing whether socioeconomic status may override biological pathways in extreme resource-limited settings.
methodsWe conducted a multi-center cross-sectional study of 600 Yemeni university students (aged 18-25). Data on smoking, socioeconomic proxies, and hematological parameters were collected. We employed multivariate logistic regression, causal mediation analysis with bootstrapping, and E-value sensitivity analysis.
resultsNon-smokers had substantially higher odds of abnormal hemoglobin (adjusted Odds Ratio [aOR] = 11.25, 95% CI: 3.45--36.70, p < 0.001) and abnormal Mean Corpuscular Hemoglobin Concentration (aOR = 3.41, 95% CI: 1.58--7.35, p = 0.002) compared to smokers. Mediation analysis suggested that 38% of smoking's total effect on hemoglobin was mediated through nutritional pathways (indirect effect = 0.24, 95% CI: 0.08--0.45). The paradoxical association was significantly stronger among students from lower socioeconomic backgrounds (interaction p = 0.012) and females. E-value analysis (E = 4.32) indicated that substantial unmeasured confounding would be needed to explain away this association.
conclusionThese findings suggest a "healthy smoker" paradox in a humanitarian crisis context, where smoking status may serve as a proxy for higher SES and better nutritional access. This is consistent with the hypothesis that fundamental social causes can reverse established biological risk associations in contexts of extreme deprivation.
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