Long-term exposure to ambient air pollution and incident nephritis: A prospective cohort study in the UK Biobank

Abstract

Substantial studies have highlighted the implications of air pollution in relation to several kidney diseases. However, studies on the relationships of long-term exposure to NO₂, NO_x, PM_2.5, PM_2.5-10, PM₁₀ with the incidence of nephritis are relatively scarce. In our prospective cohort study, 446,626 participants from the UK Biobank who had no kidney diseases at baseline were enrolled. Annual concentrations of particulate matter (PM) with diameters ≤2.5 μm (PM_2.5), between 2.5 and 10 μm (PM_2.5–10), and ≤10 μm (PM₁₀), as well as nitrogen dioxide (NO₂) and nitrogen oxides (NO_x) were gauged by land-use regression models. We employed Cox proportional hazards models to examine the associations of air pollutants with the incidence of nephritis, adjusted for potential covariates. We applied restricted cubic spline (RCS) analysis to find the exposure-response relationship. 3,455 cases were observed through a median follow-up duration of 13.58 years. Our results showed the enhanced risk of nephritis was linked to per interquartile range (IQR) increase in NO₂ (hazard ratio (HR): 1.09, 95 % confidence intervals (95 %CI): 1.04–1.14) and in NO_x (1.05, 1.01–1.08). We found nonlinear relationships between the levels of NO_x, PM_2.5, and PM_2.5-10 and incident nephritis. They all displayed a tendency of initial rapid increase followed by a subsequent gradual growth. We didn't find nonlinear relationships between NO₂ and PM₁₀ concentrations and incident nephritis. Thus, exposure to air pollution may induce the incidence of nephritis, emphasizing the importance of controlling ambient air pollution for its prevention.