Associations of residential environmental factors with kidney function in older adults in the Netherlands: A cross-sectional and longitudinal study

Identifying modifiable environmental factors of chronic kidney disease (CKD) in older adults is important for developing strategies to prevent CKD. This study aimed to investigate cross-sectional and longitudinal associations of residential environmental exposure, including air pollution and walkability, with kidney function in older adults in the Netherlands. For the cross-sectional analyses, data from two cohorts of the Longitudinal Aging Study Amsterdam were used: 1992/93 (n = 1182; mean age = 72.3 ± 8.5) and 2008/09 (n = 741; mean age = 71.6 ± 7.8). Longitudinal analyses included 227 participants (mean age at baseline = 62.6 ± 5.4). Kidney function was assessed by calculating eGFR from serum creatinine measurements. PM 10 and NO 2 concentrations, along with an objectively measured walkability index within 500 m of each participant's residential address, were linked to participants at baseline. Adjusted linear regression analyses were conducted to assess the associations of interest. Participants had healthy eGFR values of 70.9, 77.0, and 75.5 ml/min/1.73 m 2 in the 1992/93 cohort, 2008/09 cohort, and longitudinal sample, respectively. After adjustment for age, sex, educational level, body mass index, smoking status, cardiovascular disease, walkability, and NO 2, higher PM 10 concentrations were cross-sectionally associated with lower eGFR in the 2008/09 cohort, but with higher eGFR in the 1992/93 cohort. In the fully adjusted model, NO 2 exposure showed no association with eGFR in 2008/09, but was associated with higher eGFR in 1992/93. Higher levels of neighborhood walkability were associated with higher eGFR in cohort 2008/09, but with lower eGFR in 1992/93. No significant associations were observed between air pollution or walkability at baseline and changes in eGFR over the 16-yr follow-up. However, trends suggest potential longitudinal associations, with lower air pollution and higher walkability linked to higher eGFR. Overall, findings were inconsistent, indicating that larger longitudinal studies are needed to draw more definite conclusions.