Chronic kidney disease, hypertension are common after children undergo cardiac surgery

Children typically have chronic kidney disease and hypertension five years after undergoing cardiac surgery, according to a prospective, multicenter cohort study. The outcomes were similar whether or not children had perioperative acute kidney injury.

Lead researcher Jason H. Greenberg, MD, MHS, of Yale University School of Medicine in New Haven, Connecticut, and colleagues published their results online in JAMA Pediatrics on Sept. 12.

The researchers cited previous studies found that an estimated 25 percent to 60 percent of children undergoing cardiac surgery have acute kidney injury. They added that there was a lack of evidence regarding whether acute kidney injury in children is associated with permanent renal damage and progressive decline in kidney function.

In this study, known as TRIBE-AKI, researchers evaluated 131 children who were between one month and 18 years old and underwent cardiac surgery with cardiopulmonary bypass at Cincinnati Children’s Hospital, Montreal Children’s Hospital and Yale New Haven Children’s Hospital.

The children received annual telephone calls consisting of detailed questionnaires focused on their medical history, hospitalizations and other factors. At five years, a research nurse visited the children at their home or at the hospital clinic. The nurses measured the children's height, weight and blood pressure, collected blood and urine and gathered more information on their medical history.

At the five-year follow-up, the children's median age was 7.7 years old, and 52 percent were boys. In addition, 44 percent of the children had acute kidney injury after their index cardiac surgery.

Further, 18 percent of children had chronic kidney disease, 17 percent of the children had hypertension, 8 percent had microalbuminuria, 13 percent had an estimated glomerular filtration rate (eGFR) of less than 90 mL/min/1.73 m2 and 1 percent had an eGFR of less than 60 mL/min/1.73 m2. The researchers found that no significant differences in renal outcomes existed between children with and without postoperative acute kidney injury.

They added that the hypertension prevalence in this study was more than 10 times greater than the prevalence among the general pediatric population. Still, they noted that only seven of the children were being treated for hypertension or chronic kidney disease.

“Treatment of hypertension and [chronic kidney disease] in childhood is critical because these risk factors in children are associated with increased cardiovascular outcomes in adults,” the researchers wrote. “The impact of [chronic kidney disease] and hypertension is especially relevant in children with congenital heart disease because they are a high-risk population for long-term cardiac events.”

The researchers cited a few potential limitations of the study, including a small sample size. A large number of patients also declined to participate in the long-term follow-up period. Further, they could not obtain blood and urine samples from some children.

“Approximately 10,000 infants with congenital heart disease undergo cardiac surgery each year in the United States, and our results bear significant implications for the early detection and prevention of hypertension and [chronic kidney disease in this vulnerable population,” the researchers wrote. “These findings will provide data needed to begin making recommendations for renal follow-up after pediatric cardiac surgery. Future studies could consider using ambulatory blood pressure monitoring and echocardiogram to more accurately characterize hypertension risk and cardiac function after cardiac surgery in general, and after cardiac surgery-associated [acute kidney injury] in particular.”