Reduction in ambient PM2.5 associated with decreased risk of dialysis and mortality among patients with advanced chronic kidney disease: A population-based retrospective cohort study in Taiwan.

Fine particulate matter (PM2.5) is associated with the development of chronic kidney disease (CKD). However, studies validating the beneficial effects of reducing ambient PM2.5 levels on CKD remain limited. The Taiwan government has implemented 'Clean Air Action Plans' since 2015. We aim to investigate the effects of changes in PM2.5 on dialysis incidence and mortality among patients with advanced CKD. This retrospective population-based cohort study recruited 31,027 patients with CKD stage 3b to 5 during 2016-2020 and followed them until December 31, 2021. The change in PM2.5 (ΔPM2.5) was defined by subtracting the 365-day mean concentration before the index date from that before the end of follow-up. Cox regression models were used to assess the hazard of dialysis incidence and mortality per 1-μg/m³ reduction in PM2.5, as well as by dividing ΔPM2.5 into tertiles. Restricted cubic spline analysis was performed to delineate the concentration-response relationship between ΔPM2.5 and the outcomes. We observesed that each 1-μg/m³ reduction in ambient PM2.5 was associated with an 11 % decrease in dialysis incidence and a 14 % decrease in mortality risk. Patients in tertile 1 (with improved PM2.5) experienced a reduced risk of outcomes (hazard ratio for dialysis, 0.70; 95 % confidence interval, 0.65-0.75), while those in tertile 3 (with deteriorated PM2.5) had an increased risks compared to those in tertile 2. An approximately linear relationship between ΔPM2.5 and risk of outcomes was observed. In conclusion, improvement in ambient PM2.5 levels is significantly associated with a reduced risk of dialysis and mortality among advanced CKD patients.