Fever, infection with organisms other than Escherichia coli, elevated C-reactive protein, and an abnormal ultrasonographic finding are significant predictors of a higher risk of renal scarring among children and adolescents with a first episode of urinary tract infection, a meta-analysis has found.
Urinary tract infection (UTI) is the most common serious bacterial infection in children, and studies have shown that in 10%-15% of cases it leads to renal scarring (Pediatrics 2010;126:1084-91). If the renal scarring is considerable and results in a reduction in kidney function, it may be associated with hypertension, preeclampsia, and end-stage renal disease in adult life, studies have found (J. Hypertens. 2000;18:485-91; Pediatr. Nephrol. 1996;10:139-42).
The analysis of patient data from 1,280 individuals in nine cohort studies also showed a polymorphonuclear cell count of greater than 60% nearly doubled the risk while the presence of grades IV-V vesicoureteral reflux was associated with a 22-fold increase in the likelihood of renal scarring, defined as presence of photopenia on a technetium Tc 99m succimer renal scan.
"Although our data confirm the importance of high-grade VUR’ [vesicoureteral reflux] as a risk factor for renal scarring, they do not resolve the difficult question of how to identify this important but small subgroup of children without subjecting all children to a VCUG [voiding cystourethrogram]," reported Dr. Nader Shaikh of the Children’s Hospital of Pittsburgh, and his colleagues in a paper published online in the Aug. 4 issue of JAMA Pediatrics.
Researchers used the data to generate a predictive model using the three variables of temperature, ultrasonographic findings, and etiologic organism, whereby children with a score of two or more had twice the baseline risk of scarring (JAMA Pediatrics 2014, Aug. 4 [doi:10.1001/jamapediatrics.2014.637]).
The investigators found that 78.3% of patients are at low or intermediate risk of renal scarring from their first diagnosed UTI. They have normal renal ultrasound findings and only one of two other findings: a temperature of at least 39° C or an organism other than E. coli. Children with all three of the findings have twice the risk of renal scarring and constitute 21.7% of patients. The latter group merit close clinical follow-up and possibly a technetium Tc 99m succimer renal scan. "But the potential merits of obtaining a late scan clearly need to be explored in future prospective studies before the scan can be recommended," Dr. Nader Shaikh of the Children’s Hospital of Pittsburgh, and his colleagues wrote.
In an accompanying editorial, Dr. Kenneth B. Roberts of the University of North Carolina, Chapel Hill, said the findings shift the focus from vesicoureteral reflux to renal scarring, and confirm the value of renal-bladder ultrasonogram as a predictor of renal damage.
"High fever and organisms other than E. coli are also predictors, but notably, adding a VCUG and serum inflammatory markers to the evaluation contributes very little," Dr. Roberts wrote (JAMA Pediatrics 2014, Aug. 4 [doi:10.1001/jamapediatrics.2014.1329]).
No conflicts of interest were reported for the study or editorial.