Background: Childhood hypertension is a significant risk factor for early cardiovascular disease. Ambulatory blood pressure monitoring (ABPM) is an important tool for hypertension surveillance in pediatric kidney transplant recipients. The prevalence of posttransplant hypertension in pediatric kidney transplant recipients using the 2022 ABPM guidelines in not known.
Objective: To determine the prevalence, characteristics, and predictors of ambulatory hypertension in pediatric kidney transplant recipients
Method: We retrospectively identified all pediatric (age <22 years) kidney transplant recipients who successfully completed 24-hour ABPM for hypertension surveillance per the institutional protocol at the University of Minnesota between 1/2020 and 9/2022. We defined ambulatory hypertension using the 2022 ABPM guidelines. We compared continuous and categorical variables using the Wilcoxon rank sum and Fisher’s exact tests and used logistic regression to identify the predictors of ambulatory hypertension.
Results: Our cohort included 71 patients with median posttransplant follow-up time of 5.5 years (IQR: 7.5). Table 1 presents the baseline characteristics of the study cohort. We observed abnormal ABPM (excluding isolated nocturnal blunting) in 23/42 (54.8%) patients already on antihypertensive medications (indicating poor control) and 8/29 (27.6%) patients without an existing diagnosis of hypertension. Among those already on antihypertensive medications, 40.5% (n=17) of patients had normal clinic BP but elevated BP on ABPM. We observed isolated nocturnal hypertension in 29.6% (n=21) and blunted nocturnal dip in 39.4% (n=28) of all patients. Masked hypertension was seen in 13.8% (n=4) and white coat hypertension in 10.3% (n=3) of patients with no prior diagnosis of hypertension (table 2). After adjusting for age at transplant, race, donor type, preemptive transplantation, and BMI, the female sex was significantly protective against posttransplant ambulatory/masked hypertension (Adjusted OR: 0.19; 95% CI: 0.05, 0.72; p = 0.01). Left ventricular hypertrophy was more prevalent in children with blunted nocturnal dipping, but the difference did not achieve statistical significance (54.1% vs. 36.8; p=0.36).
Conclusion: Using the 2022 ABPM guidelines, ambulatory/masked hypertension is highly prevalent in pediatric kidney transplant recipients. Isolated nocturnal hypertension, blunted nocturnal dipping, and the male sex characterize ambulatory hypertension in this population. Clinic blood pressures may miss poorly controlled hypertension among those on antihypertensive medications. Transplant centers should consider adding 24-hour ABPM to transplant protocols to optimize the diagnosis and treatment of hypertension.