UCL Analysis of 22,000 Participants Shows Men's TB Excess Driven by Lifetime Exposure, Not Progression Risk

Researchers pooled 11 cohorts spanning Europe, Africa, Asia and South America and tracked incident active TB over time. Men entered studies with significantly higher rates of prior infection, consistent with greater cumulative exposure through occupational, social and household contacts. Once latent infection status was controlled, the hazard of developing active TB did not differ materially between sexes. The pattern held after excluding participants who received preventive therapy.

This finding reframes the global 2:1 male-to-female TB notification ratio as primarily an exposure disparity rather than a biological susceptibility gap. It aligns with earlier observational data from WHO surveillance and South African mining cohorts showing similar infection gradients by sex but diverges from smaller studies that reported male progression advantages without baseline infection adjustment. Missing smoking, alcohol and socioeconomic covariates limit causal attribution.

Future work must quantify sex-specific contact patterns and ventilation exposures in high-burden settings. Interventions targeting male-dominated workplaces or delayed male care-seeking could narrow incidence faster than progression-focused drugs alone.

Next required evidence is a cluster-randomized trial of exposure-reduction measures in male occupational groups with TB incidence as the primary endpoint measured over at least 24 months.