Table 2

Admissions related to total kidney and urinary system disease and chronic kidney disease (CKD), and association between air pollution and first hospital admission related to kidney diseases

PM2.5NO2
Total kidney and urinary system disease 
Total cohort  
 No of admissions19 195 342
 Total person years410 303 502
 Median follow-up year5
 Hazard ratio (95% CI)1.076 (1.071 to 1.081)1.040 (1.036 to 1.043)
Low pollution cohort 
 No of admissions5 233 054
 Total person years113 564 232
 Median follow-up year6
 Hazard ratio (95% CI)1.133 (1.121 to 1.145)1.021 (1.009 to 1.033)
Chronic kidney disease 
Total cohort  
 No of admissions5 902 129
 Total person years454 497 761
 Median follow-up year6
 Hazard ratio (95% CI)1.106 (1.097 to 1.115)1.013 (1.008 to 1.019)
Low pollution cohort 
 No of admissions1 638 976 
 Total person years126 479 286 
 Median follow-up year6 
 Hazard ratio (95% CI)1.202 (1.165 to 1.240)0.980 (0.920 to 1.040)

  • The low pollution cohort includes subset of cohort with annual exposures <12 µg/m3 for fine particles (PM2.5) and 20 ppb for nitrogen dioxide (NO2) over the study period. Hazard ratio: for each 5 µg/m3 increase in PM2.5 and 10 ppb increase in NO2.