Study Finds Particulate Matter Exposure Associated With Incident CKD

High levels of ambient particulate matter (PM_2.5) significantly increased the risk of chronic kidney disease (CKD), according to new study findings published in American Journal of Kidney Diseases. The aim of the study was to estimate the risk of incident CKD associated with long-term exposure to ambient PM_2.5 in mainland China.

The longitudinal study took place in Hunan, China, between 2005 and 2018. All participants (N = 72,425) underwent an annual physical examination at the Health Management Center in the Third Xiangya Hospital of Central South University.

Annual PM_2.5 concentrations were taken from the China High Air Pollutants (CHAP) dataset from 2000 to 2018. Two main indicators of PM_2.5 were calculated for each participant: the average of annual mean PM_2.5 concentrations from the year of the baseline date to the endpoint date and the previous 0- to 10-year average PM_2.5 annual mean concentration for the year of the baseline date.

Incident CKD was defined as participants with an estimated glomerular filtration rate below 60 mL/min/1.73 m² or self-reported physician diagnosed CKD. Covariates included age, sex, residence, education, body mass index, smoking and drinking status, blood pressure, fasting blood glucose, cholesterol, diabetes, hypertension, and history of cardiovascular disease (CVD).

The median (IQR) age of the participants was 38 (30-48) years, and 58% were male. The median long-term concentration exposure to PM_2.5 was 70.27 (61.21-74.88) mcg/m³ for all participants in the follow-up period.

The follow-up was a median 3.79 (2.03-5.48) years; 3.02% of participants developed incident CKD in this period, with an incidence rate of 732.45 per 100,000 people. The HR for incident risk of the previous 1-year PM_2.5 and cumulative average PM_2.5 in the highest quartile of exposure were 1.85 (95% CI, 1.57-2.15) and 2.55 (95% CI, 2.16-3.00), respectively.

The HRs of CKD were 1.28 (95% CI, 1.21-1.36) and 1.70 (95% CI, 1.58-1.85). An association was found between the previous 1-year average PM_2.5 and CKD (adjusted HR [aHR], 1.28; 95% CI, 1.21-1.36); cumulative average PM_2.5 had the stronger association (aHR, 1.71; 95% CI, 1.58-1.85).

Risk of incident CKD was higher in older adults (65 years and older), patients with diabetes and CVD, patients in areas of high humidity, and patients living in environments with lower temperatures when PM_2.5 was more than 74.88 mcg/m³. Overall additive interaction was only found for humidity.

In sensitivity analyses, long-term exposure to PM_2.5 had the greatest risk whereas that for the 1-year average PM_2.5 for CKD became insignificant after adjusting for common air pollutants.

The study has some limitations. It did not account for socioeconomic status that may be associated with development of CKD, data on population density were not available for this study, and the researchers did not have data on indoor air pollution exposure, fixed addresses for assessing PM_2.5 exposure, and participants’ activity levels.

The researchers concluded that there was a positive association of long-term ambient PM_2.5 exposure with risk of incident CKD in areas of high concentration.

“These findings support the conclusion that long-term exposure to PM_2.5 poses a significant health risk to the general population, and additional measures and strategies are therefore needed to reduce the burden of disease caused by PM_2.5 air pollution,” the authors wrote.

Reference

Duan JW, Li YL, Li SX, et al. Association of long-term ambient fine particulate matter (PM_2.5) and incident CKD: a prospective cohort study in China. Am J Kidney Dis. Published online April 22, 2022. doi:10.1053/j.ajkd.2022.03.009