Disparities in the burden of tuberculosis associated with urbanization across 178 countries and territories: an observational study

Background Tuberculosis (TB) remains the leading cause of death from a single infectious agent. However, there is limited quantitative evidence on the impact of urbanization on TB burden. We aimed to assess the relationship between urbanization and the global TB burden. Methods Using multi-source data, we developed a composite index of urbanization across 178 countries and territories from 2012 to 2019, incorporating the proportion of urban population, the proportion of population using improved sanitation, nighttime light intensity, normalized difference vegetation index, and per capita gross domestic product. Fixed-effects linear models were applied to estimate the rate ratios (RRs) and 95% confidence intervals (CIs) for the association between urbanization and the incidence, prevalence, and mortality of total TB and three subtypes: drug-susceptible TB (DS-TB), multidrug-resistant TB (MDR-TB), and extensively drug-resistant TB (XDR-TB). Results Overall, higher urbanization scores were associated with significant reductions in the burden of MDR-TB and XDR-TB but showed no effect on total TB or DS-TB. For MDR-TB, each additional urbanization score was associated with a 1.0% decrease in incidence (RR = 0.990; 95% CI: 0.985–0.996), a 1.1% decrease in prevalence (0.989; 0.984–0.994), and a 0.7% decrease in mortality (0.993; 0.988–0.998). For XDR-TB, the corresponding reductions were 0.9% in incidence (0.991; 0.986–0.996), 1.0% in prevalence (0.990; 0.985–0.995), and 0.7% in mortality (0.993; 0.988–0.998). These relationships persisted when considering a one-year lag in urbanization. In subgroup analyses, however, urbanization was associated with increased MDR-TB and XDR-TB burdens in upper-middle-income countries. Conclusion Urbanization was linked to reduced MDR-TB and XDR-TB burdens globally, but to increased burdens in upper-middle-income countries. Building well-managed and healthy cities is essential not only for sustainable urbanization but also for strengthening TB prevention and control, especially in rapidly transitioning upper-middle-income countries.