Climate Vulnerability Index as an Independent Predictor of Post-Transplant Infections in a National Kidney Transplant Cohort

Authors:
Kyle Jackson, Ting Lu

Body of Abstract:
Background: Post-transplant infections remain one of the leading causes of morbidity and mortality after kidney transplantation (KT). Current risk stratification tools focus exclusively on clinical and immunologic factors and do not incorporate place-based environmental and social conditions that may shape infection susceptibility. The Climate Vulnerability Index (CVI) is a validated composite metric that captures cumulative climate stressors, infrastructure limitations, and social vulnerability at the community level – factors that may influence infection susceptibility but are not reflected in current post-KT risk stratification.

Methods: We studied adult, first-time KT recipients in the United States Renal Data System from 2016–2021 with Medicare as their primary payer. KT recipient ZIP codes at transplant were linked to tract-level CVI scores using the 2019 HUD–USPS crosswalk and categorized into quartiles. Infections were identified using ICD-10 codes and grouped into clinically relevant subtypes. Cumulative incidence functions accounted for the competing risk of death. Multivariable Cox models quantified associations between CVI and post-KT infection risk, adjusted for donor, recipient, and transplant characteristics.

Results: We identified 59,665 KT recipients, 61.7% of whom resided in high-CVI communities. We found a strong and dose-dependent relationship between CVI and infection risk, with recipients in high CVI locations (i.e., high climate vulnerability) being more likely to develop a post-KT infection than recipients in low CVI locations (i.e., low climate vulnerability). By 1-year post-KT, 54.6% of recipients in the highest CVI quartile developed an infection, compared to 47.0% in the lowest quartile (p<0.001). Higher climate vulnerability was independently associated with increased infection risk (aHR 1.11 per quartile increase in CVI; 95% CI, 1.09–1.13, p<0.001). Associations were stronger for several clinically consequential infection subtypes, including Cytomegalovirus (aHR 1.19, 95% CI 1.16–1.23), endemic fungal infections (aHR 1.15, 95% CI 1.07–1.24, p<0.001), hepatitis (aHR 1.14, 95% CI 1.09–1.19, p<0.001), urinary tract infection (aHR 1.14, 95% CI 1.11–1.16, p<0.001), and respiratory viral infection (aHR 1.14, 95% CI 1.09–1.18, p<0.001). Conclusions: Climate vulnerability is an important and independent determinant of post-KT infection risk and meaningfully stratifies post-KT infection risk beyond conventional clinical predictors. Incorporating climate vulnerability into post-KT risk assessment could help identify patients who may benefit from enhanced surveillance, targeted prophylaxis, and more intensive infectious disease follow-up to mitigate preventable post-transplant complications.