VUR-Related Renal Scarring Characterized

Older age and a second episode of urinary tract infection identified as risk factors.
Older age and a second episode of urinary tract infection identified as risk factors.

Renal scarring in children with vesicoureteral reflux (VUR) is more likely to occur in older rather than younger patients and in those with a second episode of urinary tract infection (UTI), according to a new study.

The study, led by Tej K. Mattoo, MD, of the Children's Hospital of Michigan and Wayne State University in Detroit, also found that antibiotic prophylaxis did not decrease the risk of renal scarring, confirming previous research.

The findings are from an analysis of data from 599 participants in the Randomized Intervention for Children with Vesicoureteral Reflux (REVUR) trial, which evaluated the role of antimicrobial prophylaxis in the prevention of recurrent urinary tract infection (UTI) and renal scarring in children with grade 1–4 VUR. Children received either trimethoprim-sulfamethoxazole prophylaxis or placebo and follow-up for 2 years. Investigators evaluated renal scarring by at baseline and follow-up using 99mtechnetiuim dimercaptosuccinic acid (DMSA) renal scans that were reviewed independently by 2 blinded radiologists.

At the end of the study, 58 (10%) of the children had renal scarring, including 40 (69%) with new scarring, Dr. Mattoo and his colleagues reported online ahead of print in the Clinical Journal of the American Society of Nephrology. Renal scarring was present in 63 (5%) of 1,197 renal units. New renal scarring did not differ between the prophylaxis and placebo arms, occurring in 6% and 7% of patients, respectively, and in 4% of renal units in both groups.

Children with renal scarring were significantly older than those without (median 26 vs. 11 months) and were 2.8 times as likely to have had a second UTI prior to study enrollment.

The authors noted that their finding that antibiotic prophylaxis does not prevent renal scarring is similar is to that other recent studies examining the role of antibiotic prophylaxis in preventing renal scarring. “However, these results should not be interpreted as conclusive evidence against the role of antimicrobial prophylaxis in preventing renal scarring,” the authors wrote. “None of these studies, including the RIVUR trial, were designed primarily to evaluate the role of antibiotic prophylaxis in preventing renal scarring.” Dr. Mattoo's group pointed out that a follow-up of 1–2 years “may have been too short to determine long-term risk for the development of renal scarring or the effect of antimicrobial prophylaxis in its prevention.”

The authors concluded that they believe that their data “are a true representation of renal scarring as diagnosed by DMSA renal scans in young children in the United States with grade 1– 4 VUR diagnosed after UTI.”

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