Neighborhood Ambient Air Pollution and Post-Transplant Outcomes in Older Kidney Transplant Recipients

Elevated concentrations of air pollutants in residential neighborhoods are associated with poorer survival, cognitive, and cardiovascular health among older adults. Older kidney transplant (KT) recipients may be more vulnerable due to chronic immunosuppression and age-related co-morbidities. Therefore, we quantified the associations between pollutant concentrations and post-KT outcomes among older recipients.

We identified older (age ≥ 55) Black and White KT recipients from the national registry (2003-2019) linked to Medicare claims. Annual pollutant concentrations (particulate matter ≤ 2.5 μm [PM_2.5], particulate matter ≤ 10 μm, [PM₁₀], nitrogen dioxide [NO₂], and sulfur dioxide [SO₂]) were obtained from the Center for Air, Climate and Energy Solutions, and matched by ZIP code and year of KT. We used shared frailty models (cluster = state) to estimate the adjusted hazard ratios (aHR) of mortality and death-censored graft failure (DCGF) and competing risk models with cluster-robust standard errors to estimate the adjusted subhazard ratios (aSHR) of dementia and stroke by pollutant concentrations.

Among 42,199 older KT recipients, 38% were Black, 36% were female, and 82% received deceased donor KT. After adjustment, each standardized increase in pollutant concentrations was associated with significantly higher mortality risk: PM_2.5 (aHR = 1.08, 95% confidence interval [CI]: 1.07-1.10); PM₁₀ (aHR = 1.05, 95% CI: 1.03-1.07); NO₂ (aHR = 1.04, 95% CI: 1.02-1.06); SO₂ (aHR = 1.09, 95% CI: 1.08-1.11). Similarly, increasing pollutant concentrations were associated with a higher risk of DCGF. Additionally, there were no significant associations between increasing pollutant concentrations and incident dementia/stroke, except: increasing PM_2.5 and NO₂ concentrations were associated with a 3% (aSHR = 1.03, 95% CI: 1.00-1.07) and 4% higher risk of stroke (aSHR = 1.04, 95% CI: 1.02-1.07), respectively.

Residence in neighborhoods with high concentrations of ambient air pollutants can worsen patient and graft survival, as well as increase the risk of stroke among older KT recipients. Early screening and interventions targeting older recipients living in such neighborhoods may be crucial for preserving cognitive and cerebrovascular health, as well as improving longitudinal quality of life.