Acute effects of air pollution on lupus nephritis in patients with systemic lupus erythematosus: A multicenter panel study in China

Air pollution may trigger systemic lupus erythematosus (SLE). However, few studies have investigated the associations between air pollution and complications of SLE, such as lupus nephritis (LN). In this study, multicenter longitudinal data from 13 hospitals in China, including 8552 SLE patients with 24,762 visits, were used. Based on the generalized estimating equation (GEE) model, we assessed the associations of LN occurrence with short-term exposures to different air pollutants including particulate matter with an aerodynamic diameter < 2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). We identified 2672 LN patients, and about half of them were from east China. Our results based on the entire data set showed that PM2.5 and NO2 were risk factors for LN within one month after exposure, with odds ratio of 1.16 (95% confidence interval (CI), 1.08–1.19) at lag 18 day and 1.19 (95% CI, 1.12–1.26) at lag 16 day relative to an interquartile range (IQR) increase in PM2.5 and NO2, respectively. This positive association between LN and NO2 was also observed for south, west, and east China. In addition, we found that the short term exposure to CO and O3 was not generally associated with LN. Finally, the negative associations of LN with SO2 were found for the entire region and east China. Our results implied that SLE patients may gain the health benefits of air quality improvement in China. Our work also provided evidence that short-term variations in air pollution may trigger LN, and further studies are needed to confirm these findings and the potential pathogenic mechanisms should be explored.