30 - Blood Pressure and Glomerular Filtration Rate Variability in Pediatric Kidney Transplant Recipients: An Improving Renal Outcomes Collaborative (IROC) Study

Poster Number: 30
Publication Number: 30.235

Ashley M. Gefen, Cohen Children's Medical Center, New York, NY, United States; Christine Sethna, Cohen Children's Medical Center, New Hyde Park, NY, United States; Pamela Singer, Long Island Jewish Medical Center, New Hyde Park, NY, United States

Background: In children, hypertension after kidney transplantation has been associated with shortened graft survival. Visit-to-visit blood pressure variability (BPV) and estimated glomerular filtration rate variability (eGFRV) are defined as the overall fluctuation in blood pressure (BP) and eGFR over time. No studies have examined the role of visit-to-visit BPV and eGFRV in pediatric kidney transplantation.

Objective: To describe the distribution of and identify characteristics associated with BPV and eGFRV in the first 6 months (M) posttransplant.

Design/Methods: Data were obtained from the multicenter transplant collaborative, IROC. Participants ≤17 years of age with a kidney-only transplant and minimum of three BP and/or eGFR values were included; those with donation after cardiac death, previous kidney transplant, or graft loss/death within 1 year were excluded. Variability measures included standard deviation (SD), coefficient of variation (CV) and average real variability (ARV). BPV was calculated as variability in mean arterial pressure (MAP) and systolic/diastolic BP (SBP/DBP). eGFR was calculated using the bedside Schwartz equation. The distributions of BPV and eGFRV at 0-3, 3-6 and 0-6M posttransplant were compared using the Kruskal-Wallis Test and Mann-Whitney U Test. Multiple linear regression models examined relationships of participant characteristics with BPV and eGFRV. Recipient age and sex were included in all models as well as characteristics significant on bivariate analysis in a stepwise manner.

Results: Of the 2835 IROC participants, 270 participants with eGFRV data and 77 participants with BPV data were included. Participant characteristics are shown in Table 1. The distributions of BPV as MAP, SBP and DBP variability over 0-6, 0-3 and 3-6M were not significantly different (all p < 0.05). The distributions of eGFRV ARV at 0-6 vs. 3-6M (p=0.005) as well as at 0-3 vs. 3-6M (p=0.003) were significantly different (Figure 1). For multivariate regressions (Table 2), older donor age was associated with greater BPV MAP ARV at 0-3M (β 0.153, 95%CI 0.039 to 0.266, p=0.01). Younger recipient age was associated with greater eGFRV ARV at 0-3M (β -0.82, 95%CI -1.192 to -0.448-0.266, p < 0.01) and 0-6M (β -0.744 95%CI -1.013 to -0.476, p < 0.001).Conclusion(s): BPV was stable over the first 6M and eGFRV was lower at 3-6M compared to 0-6 and 0-3M posttransplant. Younger recipient age was a significant predictor of greater eGFRV. Older donor age was a predictor of greater BPV at 0-3M. Further study is necessary to investigate effects of BPV and eGFRV on kidney transplant outcomes in children.
Table 1. Participant characteristics.BMI, body mass index; BPV, blood pressure variability; CIT, cold ischemia time; eGFRV, estimated glomerular filtration rate variability; HLA, human leukocyte antigen; IQR, interquartile range; LOS, length of stay; PRA, panel reactive antibody; SD, standard deviation; TTV, tacrolimus trough variability.
Figure 1. Distributions of BPV as MAP ARV and eGFRV as ARV for 0-3, 0-6, and 3-6 months posttransplant.ARV, average real variability; BPV, blood pressure variability; eGFRV, estimated glomerular filtration rate variability; M, months; MAP, mean arterial pressure.