Associations between long-term exposure to air pollution and kidney function utilizing electronic healthcare records:...

Chronic kidney disease (CKD) affects more than 38 million people in the United States, predominantly those over 65 years of age. While CKD etiology is complex, recent research suggests associations with environmental exposures.

Our primary objective is to examine creatinine-based estimated glomerular filtration rate (eGFR_cr) and diagnosis of CKD and potential associations with fine particulate matter (PM_2.5), ozone (O₃), and nitrogen dioxide (NO₂) using a random sample of North Carolina electronic healthcare records (EHRs) from 2004 to 2016. We estimated eGFR_cr using the serum creatinine-based 2021 CKD-EPI equation. PM_2.5 and NO₂ data come from a hybrid model using 1 km² grids and O₃ data from 12 km² CMAQ grids. Exposure concentrations were 1-year averages. We used linear mixed models to estimate eGFR_cr per IQR increase of pollutants. We used multiple logistic regression to estimate associations between pollutants and first appearance of CKD. We adjusted for patient sex, race, age, comorbidities, temporality, and 2010 census block group variables.

We found 44,872 serum creatinine measurements among 7,722 patients. An IQR increase in PM2.5 was associated with a 1.63 mL/min/1.73m² (95% CI: -1.96, -1.31) reduction in eGFRcr, with O₃ and NO₂ showing positive associations. There were 1,015 patients identified with CKD through e-phenotyping and ICD codes. None of the environmental exposures were positively associated with a first-time measure of eGFR_cr < 60 mL/min/1.73m². NO₂ was inversely associated with a first-time diagnosis of CKD with aOR of 0.77 (95% CI: 0.66, 0.90).

One-year average PM_2.5 was associated with reduced eGFR_cr, while O₃ and NO₂ were inversely associated. Neither PM_2.5 or O₃ were associated with a first-time identification of CKD, NO₂ was inversely associated. We recommend future research examining the relationship between air pollution and impaired renal function.