Short-term exposure to air pollution and acute kidney injury-related mortality: a global time-series study in 136 cities in 6 countries

BACKGROUND AND AIM: Recent studies have shown the association between air pollution and chronic kidney disease. However, less is known about effects of exposure to air pollution on acute kidney injury (AKI) and resultant disease burden. Therefore, this study aimed to estimate the short-term association between three air pollutants (PM2.5, O3, and NO2) and AKI-related death using a multi-city multi-country database. METHOD: We obtained data on daily time-series of AKI-related death count and concentration of air pollutants for 136 cities across the six countries during the period 1987–2018 from the Multi-City Multi-Country (MCC) Collaborative Research Network. We conducted a novel case time-series design with quasi-Poisson distribution to estimate the association between each air pollutant and AKI-related death and calculated the excess deaths due to noncompliance with the new WHO air quality guidelines. Air pollutant was included in a model using a distributed lag model (DLM) with 35 lag days. RESULTS: Total of 41,379 AKI-related deaths were included in this study. AKI-related deaths were positively associated with air pollutants, with RRs of 1.06 (95% CI: 0.99, 1.12) for PM2.5, 1.03 (95% CI: 0.99, 1.08) for warm season (April to September) O3, and 1.03 (95% CI: 0.98, 1.08) for NO2, per 5, 10, and 10 µg/m3 increase in each air pollutant. In lag-distributed associations, the risks of AKI death tended to decrease during the early lag periods and started to increase after 15 lag days for PM2.5 and warm season O3. Proportions of excess AKI deaths attributable to air pollutant levels above the new WHO guidelines were 2.6%, 5.1%, and 4.7% for PM2.5, warm season O3, and NO2, respectively. CONCLUSIONS: Our findings provide evidence that short-term exposure to air pollution is associated with an increased risk of AKI-related death and implications on disease burden of AKI attributable to air pollution.