Ambient Air Particulate Matter and Hospital Admissions for Chronic Kidney Disease in China: A Nationwide Case-Crossover Study

Incident chronic kidney disease (CKD) may be accelerated (could be indicated by repeated admissions to the hospital) by environmental triggers such as ambient particulate matter (PM). Additionally, hospital admission is a sensitive proxy reflecting the disease burden. However, the association of PM exposure with hospital admissions for CKD is still unknown, let alone the excess risks (ERs) in hospital admissions for CKD due to high PM level exposure. In this study, a two-stage time-stratified case-crossover study was conducted to investigate the association of ambient air PM exposure with hospital admission for CKD in 282 Chinese cities of prefecture-level or above during 2013-2017. City-specific associations of single and cumulative 0-3 days lagged exposure to fine particulate matter (PM_2.5) and inhalable particles (PM₁₀) with hospital admissions for total CKD and its subtypes were evaluated by the conditional logistic regression model, then were pooled using the random-effect model. A total of 3,490,416 hospital admissions for CKD were identified. We found that per interquartile range (IQR) increment in PM_2.5 at lag02 and per IQR increment in PM₁₀ at lag03 were associated with increases of 2.36% (95%CI: 1.58%, 3.14%) and 2.87% (95% CI:1.91%, 3.85%) in hospital admissions for total CKD, respectively. Compared to control concentrations (PM_2.5: 35 μg/m³; PM₁₀: 50 μg/m³), the largest ERs in hospital admissions for total CKD were 2.63% (95% CI: 2.15%-3.11%) and 4.45% (95% CI: 3.85%-5.06%) in association with exposure to heavily excessive PM_2.5 (≥75 μg/m³) and PM₁₀ (≥150 μg/m³), respectively. Moreover, the attributable fractions (AFs) for CKD admissions were 2.83% for PM_2.5 and 3.46% for PM₁₀ during the study period. These findings suggested that exposure to PM_2.5 and PM₁₀ is associated with substantially increased risk and burden of CKD admissions.