Associations of Air Pollution and Serum Biomarker Abnormalities in Individuals with Hemodialysis- Dependent Kidney Failure

Abstract

Key Points Exposure to daily air pollution was associated with lower serum hemoglobin and albumin among patients receiving in-center hemodialysis. Inflammation could play a key role in the air pollution-related risk of mortality and cardiovascular disease among patients with hemodialysis. Patients with renal disease may be differentially vulnerable to health effects after air pollution exposure. Background Ambient particles with a median aerodynamic diameter of <2.5 μm (PM 2.5) is a ubiquitous air pollutant with established adverse health consequences. While postulated to promote a systemic inflammatory response, limited studies have demonstrated changes in serum biomarkers related to PM 2.5 exposure. We aim to examine associations between short-term PM 2.5 exposure and commonly measured biomarkers known to be affected by inflammation among patients receiving maintenance in-center hemodialysis. Methods We conducted a retrospective open cohort study from January 1, 2008, to December 31, 2014. Adult hemodialysis patients were identified from the United States Renal Data System and linked at the patient level to laboratory data from a large dialysis organization. Daily ambient PM 2.5 was estimated on a 1-km grid and assigned to cohort patients based on the ZIP codes of dialysis clinics. Serum albumin, serum ferritin, transferrin saturation (TSAT), and serum hemoglobin were ascertained from the dialysis provider organization database. Mixed-effect models were used to assess the changes in biomarker levels associated with PM 2.5 exposure. Results The final cohort included 173,697 hemodialysis patients. Overall, the daily ZIP-level ambient PM 2.5 averages were 8.4-8.5 μg/m 3. A 10-μg/m 3 increase in same-day ambient PM 2.5 exposure was associated with higher relative risks of lower albumin (relative risk [RR], 1.01; 95% confidence interval [95% CI], 1.01 to 1.02) and lower hemoglobin (RR, 1.02; 95% CI, 1.01 to 1.03). Associations of same-day ambient PM 2.5 exposure and higher ferritin and lower TSAT did not reach statistical significance. Conclusions Short-term PM 2.5 exposure was associated with lower serum hemoglobin and albumin among patients receiving in-center hemodialysis. These findings lend support to the role of inflammation in PM 2.5 exposure-outcome associations.