CHICAGO – according to a review of 690 pediatric patients in the Chronic Kidney Disease in Children Cohort Study.
Hypertensive children with CKD were less likely to progress to dialysis or kidney transplant or have a 30% decline in estimated glomerular filtration rate (eGFR) when kept in that range, compared with children above or below it. “Achieved office [blood pressure] between the 50th and 75th percentiles appeared to offer the greatest protection against CKD progression in this cohort,” said investigators led by Joseph Flynn, MD, chief of the nephrology division at Seattle Children’s Hospital.
“We needed to have some [evidence] on what to do based on office blood pressure,” something that had been missing in the literature until now. “I think this is going to be very impactful on the care of children with CKD. Right now, the guidelines say to keep” pressures below the 90th percentile for age and height. “The guidelines [might] need to be changed,” said Dr. Flynn, also the lead author of the American Academy of Pediatrics 2017 blood pressure guidelines for children and adolescents (Pediatrics. 2017 Aug 21.).
There was “no evidence to go below the 50th percentile; the 50th-75th seems to be the sweet spot for office blood pressure,” he said at the joint scientific sessions of the AHA Council on Hypertension, the AHA Council on Kidney in Cardiovascular Disease, and the American Society of Hypertension.
The 476 children with nonglomerular CKD actually did worse when their blood pressures were pushed below the 50th percentile, perhaps because of renal hypoperfusion. The 476 children with glomerular CKD did no better or worse below the 50th percentile than they did in the 50th-75th.
Children at or above the 90th percentile had the highest risk of progression, with about 80% needing renal replacement therapy or having a 30% drop in eGFR at 5-8 years of follow-up. Compared with children with glomerular CKD who were in the 90th percentile, the risk hazard (RH) for progression over 3 years was 0.10-0.30 (P less than 0.001) among those children with glomerular CKD who were kept in the 50th-75th percentile. Compared with children with nonglomerular CKD who were in the 90th percentile, the RH over 8 years among those in the 50th-75th percentile was 0.48 (P less than 0.001). Risk of progression in both glomerular and nonglomerular patients in the sweet spot was less than 50% at 5-8 years of follow-up.
When glomerular and nonglomerular patients were considered together, those with pressures below the 50th percentile were less likely to progress than children with pressures between the 75th and 90th, but they were more likely to progress than the 50th-75th percentile group.
Research nurses took three blood pressures by auscultation a minute apart after 5 minutes of rest. Most of the children were treated at first with angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blockers, per recommendations. Dihydropyridine calcium channel blockers (for example, amlodipine and nifedipine) were most likely to be used next.
It was a curious finding because dihydropyridines have been show to worsen proteinuria in adults with CKD. The team is investigating to see whether they have the same effect in children. If so, “we’ll be able to tell people to stop using them,” Dr. Flynn said.
The median age in the study was 11.3 years, and almost two-thirds of the subjects were boys. The median duration of disease was 8 years. Some children in the ongoing cohort have been followed for almost 10 years. The analysis is based on children who entered the cohort with hypertension or developed it after enrollment.
The nationwide Chronic Kidney Disease in Children Cohort Study is funded by the National Institutes of Health. Dr. Flynn is an advisor for Ultragenyx and Silvergate Pharmaceuticals.