Acute Kidney Injury and Risk of CKD and Hypertension after Pediatric Cardiac Surgery

Abstract

Background and objectives: The association of AKI after pediatric cardiac surgery with long-term CKD and hypertension development is unclear. The study objectives were to determine whether AKI after pediatric cardiac surgery is associated with incident CKD and hypertension.

Design, setting, participants, & measurements: This was a prospective cohort study of children of 1 month to 18 years old who were undergoing cardiac surgery at two tertiary care centers (Canada, United States). Participants were recruited before cardiac surgery and were followed during hospitalization and at 3, 12, 24, 36, and 48 months after discharge. Exposures were postoperative AKI, based on the Kidney Disease Improving Global Outcomes (KDIGO) definition, and age <2 years old at surgery. Outcomes and measures were CKD (low eGFR or albuminuria for age) and hypertension (per the 2017 American Academy of Pediatrics guidelines) at follow-up, with the composite outcome of CKD or hypertension.

Results: Among 124 participants, 57 (46%) developed AKI. AKI versus non-AKI participants had a median (interquartile range) age of 8 (4.8-40.8) versus 46 (6.0-158.4) months, respectively, and higher preoperative eGFR. From the 3- to 48-month follow-up, the cohort prevalence of CKD was high (17%-20%); hypertension prevalence was also high (22%-30%). AKI was not significantly associated with the development of CKD throughout follow-up. AKI was associated with hypertension development at 12 months after discharge (adjusted relative risk, 2.16; 95% confidence interval, 1.18 to 3.95), but not at subsequent visits. Children aged <2 years old at surgery had a significantly higher prevalence of hypertension during follow-up than older children (40% versus 21% at 3-month follow-up; 32% versus 13% at 48-month follow-up).

Conclusions: CKD and hypertension burden in the 4 years after pediatric cardiac surgery is high. Young age at surgery, but not AKI, is associated with their development.

Keywords: acute kidney injury; acute renal failure; chronic kidney disease; clinical hypertension; epidemiology and outcomes; pediatric intensive care medicine; pediatric nephrology.

Graphical abstract

Figure 1.

Flow diagram depicting number of AKI and non-AKI patients between each study visit. The flow diagram displays eligible patients with and without AKI who completed follow-up, in-person study visits. Reasons for exclusions from study visits are shown (“other” refers to inability to perform the visit or invalid visit). The following data are unavailable: (1) total number of potentially eligible patients in preoperative clinics that we were unable to approach; (2) characteristics and number of patients who were not approached for eligibility in preoperative clinics; and (3) number of patients found to be ineligible after screening in preoperative clinics. V3M, 3-month visit; V12M, 12-month visit; V24M, 24-month visit; V36M, 36-month visit; V48M, 48-month visit.

Figure 2.

Decrease in outcome prevalence over time after cardiac surgery. Prevalence of CKD and hypertension in the whole cohort, from 3 to 48 months after cardiac surgery discharge. In each graph, dots are the point estimates of prevalence (proportions of participants) of the outcome (y axis). Bars represent the upper and lower 95% confidence interval estimates. (A) CKD (low eGFR or high albumin-creatinine ratio) at 3–48 months postdischarge (x axis). (B) Hypertension (systolic or diastolic BP ≥95th percentile for height, age, and sex) at 3–48 months. (C) CKD or hypertension at all study visits.