Exposure to ambient air pollutants and incident chronic kidney disease in patients with hypertension: a CHARLS-based study.

BACKGROUND

Long-term exposure to ambient air pollutants is increasingly recognized as detrimental to kidney health, yet its association with incident chronic kidney disease (CKD) among people diagnosed with hypertension remains poorly elucidated.

OBJECTIVE

To investigate the link between exposure to multiple ambient air pollutants [NO2, O3, particulate matter (PM)1, PM2.5, PM10] and CKD among middle-aged and older adults with hypertension, while simultaneously assessing whether lipid biomarkers mediate this association.

METHODS

The study population was drawn from the China Health and Retirement Longitudinal Study and comprised 3,041 participants with hypertension aged ≥ 45 years, all of whom were CKD-free at baseline in 2011. Participants were followed up until they were diagnosed with CKD or the year 2020. The effects of ambient air pollutants were examined using continuous-time Cox proportional hazards models, with models adjusted for relevant confounders encompassing demographic characteristics, lifestyle factors, and comorbidities. Mediation analyses were carried out for the evaluation of lipid biomarkers as potential mediators.

RESULTS

Throughout the follow-up, CKD was documented in 334 participants, with an overall incidence of 10.98%. In fully adjusted Cox proportional hazards models, significant associations were found between exposures to PM1, PM2.5, and PM10 and the risk of developing CKD, and these associations demonstrated robust dose-response trends across quartiles. Findings from mediation analyses indicated that the non-high-density lipoprotein (NHDL) to HDL ratio (NHHR) acted as a partial mediator for the association between PM2.5 exposure and CKD risk, and NHDL did so for the association between PM10 exposure and CKD risk.

CONCLUSION

In middle-aged and older adults with hypertension, long-term PM exposure is associated with elevated CKD risk, and this association is partially mediated by lipid metabolism dysregulation, specifically involving NHDL and NHHR.