Spatial-temporal pattern of tuberculosis mortality in China and its relationship with long-term PM2.5 exposure based on a causal inference approach

Abstract

Evidence on the spatial-temporal distribution of tuberculosis (TB) mortality across China and its relationship with long-term particulate matter (PM2.5) exposure is limited. We aimed to address significant gaps in our understanding of the spatial-temporal clustering patterns of TB mortality in China and provide evidence for its causal links with long-term PM2.5 exposure. Annual pulmonary TB mortality, PM2.5 concentrations, and socioeconomic factors for provinces in mainland China between 2004 and 2017 were obtained. Turning points in the temporal trend and spatial clustering patterns of pulmonary TB mortality were identified. A difference-in-differences causal inference approach was applied to estimate the long-term effect of PM2.5 exposure on the mortality. The average annual percent change of pulmonary TB mortality in China was −2.5% (95% CI: −5.6%, 0.7%), with an 11.1% annual increase in the Northwest since 2012 (P= 0.029). The hot and cold spots, determined by the local Moran’s I index, were all located in northern China, where Xinjiang in the Northwest had the highest mortality across the study period. We found a significant association between long-term PM2.5 exposure and pulmonary TB mortality, with percent increase risk of mortality (IR%) being 0.74% (95 CI%, 0.04%, 1.45%) for 1 µg/m3 increase in PM2.5 concentration. This association varied across multiple socioeconomic groups, with the highest IR% in provinces with lower level of latitude (IR% = 0.83%, 95% CI: 0.01%, 1.65%), lower quartile of gross domestic product (IR% = 1.01%, 95% CI: 0.23%, 1.80%) or higher proportion (⩾14%) of people >65 years of age (IR% = 1.24%, 95% CI: 0.44%, 2.04%). Comprehensive sensitivity analyses showed a robust adverse effect of long-term PM2.5 exposure on pulmonary TB mortality. Attention needs to be paid to the rising trend of pulmonary TB mortality in Northwest China. Our study provides the stable evidence to date of the causal association between long-term PM2.5 exposure and the risk of death from pulmonary TB, especially in low-altitude, underdeveloped, and aged provinces.