Abstract
Background
Previous studies have suggested that long-term exposure to air pollution increased the risk of chronic kidney disease and its progression. However, the effect of air pollution on the risk of acute kidney injury (AKI) has not been studied. We aim to evaluate the transient effect of air pollution on the risk of hospital-acquired AKI (HA-AKI).
Methods
We selected from the Epidemiology of AKI in Chinese Hospitalized patients (EACH2 study) AKI cases of which the onset date could be unambiguously determined. We obtained city-specific daily averages of the ambient level of particulate matter (PM2.5 and PM10), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3), from the Ministry of Environmental Protection of China. We used the time-stratified case crossover approach to examine the association between the ambient level of air pollutants and the risk of HA-AKI in the selected cases.
Results
A total of 11,293 AKI cases that met the inclusion and exclusion criteria were selected. In univariable analysis, the ambient levels of NO2 and SO2, were significantly associated with the risk of HA-AKI. In the multivariable analysis that incorporated all six pollutants in the same model, NO2 was the sole pollutant whose level remained to be associated with the risk of AKI (p < 0.001). The relationship between level of NO2 and the risk of HA-AKI appeared to be linear, with an estimated odds ratio of 1.063 (95% CI: 1.026, 1.101) for each increment of one median absolute deviance in the exposure. The association was consistent across the subgroups stratified by age, gender, baseline estimated glomerular filtration rate, AKI severity, need for intensive care, and season.
Conclusions
Higher ambient level of NO2 was associated with an increased risk of HA-AKI in hospitalized adults in China.