501 - Under Pressure: The Effect of Blood Pressure on Kidney Transplant Outcomes in Children

Publication Number: 2487.501

Aesha Maniar, Levine Children's Hospital, Charlotte, NC, United States; Yinyao Ji, Stanford University School of Medicine, Palo Alto, CA, United States; Alan Schroeder, Stanford University School of Medicine, Palo Alto, CA, United States; David M. Maahs, Stanford University School of Medicine, palo alto, CA, United States; Paul Grimm, Stanford University School of Medicine, Stanford, CA, United States; Abanti Chaudhuri, Stanford University, Palo Alto, CA, United States

Background: Permissive hypertension is commonly maintained after pediatric kidney transplantation to support graft perfusion, but its long-term effects are unclear. Optimal blood pressure (BP) targets following pediatric kidney transplantation remain undefined.

Objective: We investigated the relationship between early post-transplant blood pressure (BP) exposure and clinical outcomes in pediatric kidney transplant recipients.

Design/Methods: We conducted a retrospective cohort study of pediatric kidney transplant recipients ( < 18 years) from 2012 to 2022. BP percentile area under the curve (AUC) was calculated for the periods of 0-120 hours and 6 days-6 months post-transplant. We evaluated associations between BP AUC and: (1) eGFR slope in the immediate post-transplant period, (2) interstitial fibrosis/tubular atrophy (IFTA) at 6 months, and (3) left ventricular hypertrophy (LVH) at 6 or 12 months. Regression models were adjusted for clinical covariates including sex, age, donor type, medications and cold ischemia time .

Results: Among 216 patients (mean age 10.4 years), higher diastolic BP AUC in the first 5 days was significantly associated with faster early eGFR improvement (Table 1) (β = 0.32; 95% CI: 0.16-0.49; p < 0.001). Higher systolic BP AUC at 0-120 hours (but not 6 days-6 months) was associated with LVH at follow-up (OR = 1.08; 95% CI: 1.01-1.17; p = 0.035) (Table 2). BP AUC was not associated with IFTA (Figure 1). Older age was independently associated with lower odds of IFTA.

Conclusion(s): Elevated diastolic blood pressure in the immediate post-transplant period was associated with improved early graft function, supporting the practice of permissive hypertension in this population. While higher systolic BP in the first 5 days was linked to increased odds of left ventricular hypertrophy (LVH), this association did not persist when blood pressure normalized and was not observed for longer-term BP exposure, suggesting minimal long-term cardiovascular risk as long as the blood pressure normalized after the immediate post-transplant period. No significant relationship was found between BP percentiles and interstitial fibrosis/tubular atrophy (IFTA); however, older age at transplant was protective against fibrosis.

Diastolic BP and eGFR Improvement
In unadjusted linear regression models, a higher diastolic blood pressure (DBP) area under the curve (AUC) was significantly associated with a faster eGFR improvement (β = 0.48; 95% CI: 0.29 to 0.68; p < 0.001). This association remained statistically significant after adjustment for sex, age, donor type, and cold ischemia time (β = 0.32; 95% CI: 0.16 to 0.49; p < 0.001).

Systolic Blood Pressure and LVH
The relationship between early post-transplant blood pressure and the development of left ventricular hypertrophy (LVH) at 6 or 12 months was evaluated using logistic regression. In adjusted models, higher SBP AUC over the first five days post-transplant was significantly associated with increased odds of LVH (OR = 1.08 ; 95% CI: 1.01 to 1.17; p = 0.035).

Systolic Blood Pressure Percentile Trajectories After Transplant, Stratified by IFTA Grade at 6 Months
Systolic blood pressure (SBP) percentile trajectories from 0 to 5 days, 6 days to 6 months and 6 months to 1 year post-transplant were plotted and stratified by 6-month IFTA grade. Patients with higher IFTA grades (≥2) demonstrated consistently lower SBP percentiles over time compared to those with lower IFTA grades, though differences were subtle and did not reach statistical significance.