Urinary tract infection in small children: the evolution of renal damage over time

BACKGROUND: Our objective was to analyze the evolution of kidney damage over time in small children with urinary tract infection (UTI) and factors associated with progression of renal damage. METHODS: From a cohort of 1003 children <2 years of age with first-time UTI, a retrospective analysis of 103 children was done. Children were selected because of renal damage at index (99m)Tc-dimercaptosuccinic acid (DMSA) scintigraphy at least 3 months after UTI, and a late DMSA scan was performed after at least 2 years. Damage was classified as progression when there was a decline in differential renal function (DRF) by ≥4%, as regression when there was complete or partial resolution of uptake defects. RESULTS: Of 103 children, 20 showed progression, 20 regression, and 63 remained unchanged. There were no differences between groups regarding gender or age. In the progression group, 16/20 (80%) children had vesicoureteral reflux (VUR) grade III–V and 13 (65%) had recurrent UTI. In multivariable regression analysis, both VUR grade III–V and recurrent UTI were associated with progression. In the regression group, 16/20 (80%) had no VUR or grade I–II, and two (10%) had recurrent UTI. CONCLUSIONS: Most small children with febrile UTI do not develop renal damage and if they do the majority remain unchanged or regress over time. However, up to one-fifth of children with renal damage diagnosed after UTI are at risk of renal deterioration. These children are characterized by the presence of VUR grades III–V and recurrent febrile UTI and may benefit from follow-up.