The association between fine particulate matter (PM_2.5) and chronic kidney disease using electronic health record data in urban Minnesota

Background: Recent evidence has shown that fine particulate matter (PM_2.5) may be an important environmental risk factor for chronic kidney disease (CKD), but few studies have examined this association for individual patients using fine spatial data.

Objective: To investigate the association between PM_2.5 and CKD (estimated glomerular filtration rate [eGFR]<45 ml/min/1.73 m²) in the Twin-Cities area in Minnesota using a large electronic health care database (2012-2019).

Methods: We estimated the previous 1-year average PM_2.5 from the first eGFR (measured with the CKD Epidemiology Collaboration equation using the first available creatinine measure during the baseline period [2012-2014]) using Environmental Protection Agency downscaler modeling data at the census tract level. We evaluated the spatial relative risk and clustering of CKD prevalence using a K-function test statistic. We assessed the prevalence ratio of the PM_2.5 association with CKD incidence using a mixed effect Cox model, respectively.

Results: Patients (n = 20,289) in the fourth (PM_2.5 > 10.4), third (10.3 < PM_2.5 < 10.8) and second quartile (9.9 < PM_2.5 < 10.3) vs. the first quartile (<9.9 μg/m³) had a 2.52[2.21, 2.87], 2.18[1.95, 2.45], and 1.72[1.52, 1.97] hazard rate of developing CKD in the fully adjusted models, respectively. We identified spatial heterogeneities and evidence of CKD clustering across our study region, but this spatial variation was accounted for by air pollution and individual covariates.

Significance: Exposure to higher PM_2.5 is associated with a greater risk for incident CKD. Improvements in air quality, specifically at hotspots, may reduce CKD.