Long Term Exposure to Ambient Particulate Matter 2.5 and Kidney Function in Urban Indian Adults.

BACKGROUND

Despite epidemiological evidence linking fine particulate matter (PM2.5) to cardiometabolic diseases, links between PM2.5 and kidney function or chronic kidney disease (CKD) remain inconclusive.

METHODS

In a population representative cohort of 12,271 adults (age ≥ 20 years) in 2 Indian cities (Chennai and Delhi), we investigated time-varying associations between annual average ambient PM2.5 and estimated glomerular filtration rates (eGFR) calculated using CKD-Epidemiology Collaboration (EPI) 2009 equations, at 3 time points during 2010 to 2016. Ambient PM2.5 exposures were assessed at residential geocodes using a national high-resolution spatiotemporal model for daily PM2.5 at 1 km × 1 km. City-specific linear mixed effect models were employed, incorporating inverse probability-based weighting to account for loss-to-follow-up. Effect modification by sex, waist-to-hip ratio, hypertension, and diabetes status were assessed using stratified models.

RESULTS

Annual average PM2.5 at baseline and 2 follow-ups in Chennai were 33, 37, and 30 μg/m3 whereas those in Delhi were 118, 123, and 130 μg/m3. Median eGFRs at baseline were 112 ml/min per 1.73 m2 (interquartile range [IQR]: 101.9-121.0) in Chennai and 106.4 ml/min per 1.73 m2 (IQR: 94.4-116.6) in Delhi. Over time, a 5 ug/m3 increase in annual average PM2.5 was associated with a significant decline in eGFR in both cities as follows: -0.32 (95% confidence interval [CI]: -0.49 to -0.15) ml/min per 1.73 m2 in Chennai and -0.42 (95% CI: -0.57 to -0.27) ml/min per 1.73 m2 in Delhi.

CONCLUSION

Annual average PM2.5 levels were associated with declines in eGFR. These data from a relatively young South Asian urban cohort underscore the need to further investigate the potential renal and cardiovascular impacts of sustained air pollution exposure.