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

Permissive hypertension is often targeted in the immediate post-operative period following pediatric kidney transplantation to optimize donor kidney perfusion, particularly when adult-sized donor kidneys are transplanted into smaller recipients. However, evidence is limited regarding the optimal post-transplant blood pressure (BP) targets in children and the impact of early BP patterns on long-term outcomes such as graft function, fibrosis, and cardiovascular remodeling. We conducted a retrospective cohort study of pediatric kidney transplant recipients (<21 years old) at Stanford Children’s Hospital between 2014 and 2022. Area under the curve (AUC) for systolic and diastolic BP percentiles was calculated for two intervals: 0–120 hours (immediate post-transplant) and 6 days–6 months. We examined associations between BP AUC and (1) early improvement in kidney function (eGFR slope), (2) interstitial fibrosis and tubular atrophy (IFTA) at 6 months, and (3) left ventricular hypertrophy (LVH) at 6 or 12 months. Multivariable regression models were used to adjust for relevant covariates including age, donor type, and cold ischemia time. Variables considered but not included were sex and height, given that our primary exposure (blood pressure) accounted for sex and height Elevated blood pressure in the immediate post-transplant period, particularly among younger recipients, 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. No significant relationship was found between BP and interstitial fibrosis/tubular atrophy (IFTA); however, older age at transplant was protective against fibrosis. These findings support an individualized, age-informed approach to early BP management after pediatric kidney transplant.