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

Importance: Ambient PM2.5 is a ubiquitous air pollutant with established adverse health impact in the general population. However, the pathological mechanisms underlying PM2.5 exposure are not fully understood. Objective: To examine associations between short-term PM2.5 exposure and a group of commonly measured biomarkers affected by inflammation among patients receiving maintenance in-center hemodialysis. Design: We conducted a retrospective open cohort study from 1/1/2008 to 12/31/2014. Setting: Study participants were identified by linkage between United States Renal Data System and a large dialysis organization’s database. Participants: Adult hemodialysis patients were included if they initiated dialysis during the study period, had Medicare as primary payer, and had at least one outcome of interest available. Exposure: Daily ambient PM2.5 was estimated on a 1 km grid for the entire contiguous US and assigned to cohort patients based on the ZIP code of the dialysis clinic. Main Outcomes and Measures: Serum albumin, serum ferritin, transferrin saturation (TSAT), and serum hemoglobin were extracted from the dialysis provider’s database. Mixed-effect models were used to assess the change in biomarker concentrations associated with PM2.5 exposure. Results: Among 173,697 hemodialysis patients included, over half of the participants were older than 65 at the initiation of hemodialysis,  44% were female, and 62.8% were white race. Overall, the daily ZIP-level ambient PM2.5 averages were 8.4 to 8.5 µg/m3, and the inter-quartile ranges (IQRs) were 5.9 to 6.0 µg/m3 for dates when each biomarker was measured. The average follow-up period for this cohort was 2.6 (STD = 1.7) years. A 10 µg/m3 increase in same-day ambient PM2.5 exposure was associated with higher relative risk of low albumin (RR: 1.01, 95%CI: 1.01, 1.02) and high ferritin (RR: 1.04, 95%CI: 0.99, 1.09); lower risk of low TSAT (RR: 0.98, 95%CI: 0.97, 0.99), and higher risk of low hemoglobin (RR: 1.02, 95%CI: 1.01, 1.03). Conclusions and Relevance: Short-term PM2.5 exposure was associated with changes in levels of regularly measured biomarkers among patients receiving in-center hemodialysis. The findings support the previously suggested role of inflammation in the pathological mechanism of PM2.5 exposure.

Impact/Purpose

Importance: Ambient PM2.5 is a ubiquitous air pollutant with established adverse health impact in the general population. However, the pathological mechanisms underlying PM2.5 exposure are not fully understood. Objective: To examine associations between short-term PM2.5 exposure and a group of commonly measured biomarkers affected by inflammation among patients receiving maintenance in-center hemodialysis. Design: We conducted a retrospective open cohort study from 1/1/2008 to 12/31/2014. Setting: Study participants were identified by linkage between United States Renal Data System and a large dialysis organization’s database. Participants: Adult hemodialysis patients were included if they initiated dialysis during the study period, had Medicare as primary payer, and had at least one outcome of interest available. Exposure: Daily ambient PM2.5 was estimated on a 1 km grid for the entire contiguous US and assigned to cohort patients based on the ZIP code of the dialysis clinic. Main Outcomes and Measures: Serum albumin, serum ferritin, transferrin saturation (TSAT), and serum hemoglobin were extracted from the dialysis provider’s database. Mixed-effect models were used to assess the change in biomarker concentrations associated with PM2.5 exposure. Results: Among 173,697 hemodialysis patients included, over half of the participants were older than 65 at the initiation of hemodialysis,  44% were female, and 62.8% were white race. Overall, the daily ZIP-level ambient PM2.5 averages were 8.4 to 8.5 µg/m3, and the inter-quartile ranges (IQRs) were 5.9 to 6.0 µg/m3 for dates when each biomarker was measured. The average follow-up period for this cohort was 2.6 (STD = 1.7) years. A 10 µg/m3 increase in same-day ambient PM2.5 exposure was associated with higher relative risk of low albumin (RR: 1.01, 95%CI: 1.01, 1.02) and high ferritin (RR: 1.04, 95%CI: 0.99, 1.09); lower risk of low TSAT (RR: 0.98, 95%CI: 0.97, 0.99), and higher risk of low hemoglobin (RR: 1.02, 95%CI: 1.01, 1.03). Conclusions and Relevance: Short-term PM2.5 exposure was associated with changes in levels of regularly measured biomarkers among patients receiving in-center hemodialysis. The findings support the previously suggested role of inflammation in the pathological mechanism of PM2.5 exposure.

Citation

Xi, Y., D. Richardson, A. Kshirsagar, J. Flythe, E. Whitsel, Tim Wade, AND A. Rappold. Associations of Air Pollution and Serum Biomarker Abnormalities in Individuals with Hemodialysis-Dependent Kidney Failure. American Society of Nephrology (ASN), Washington, DC, 4(1):63-68, (2023). [DOI: 10.34067/KID.0003822022]

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