First episode of febrile urinary tract infection in children, detection and risk factors of kidney scarring: A prospective cohort study.

Aims: This prospective study aimed to evaluate the characteristics and findings of children who presented with acute pyelonephritis (APN) and to determine the independent risk factors for kidney scarring.
Material and Methods: Patients who satisfied the following criteria were enrolled in the study: first known episode of APN; at least two of the following findings: fever ≥ 38.5 °C, white blood cell count ≥ 10,000/mm ³ , erythrocyte sedimentation rate ≥ 20 mm/h, C-reactive protein ≥ 20 mg/dL; absence of congenital abnormalities or other kidney and systemic diseases, except vesicoureteral reflux (VUR); no APN relapses until the time of kidney scar detection. ^99m Tc-Dimercaptosuccinic acid kidney scintigraphy ( ^99m Tc-DMSA) was performed at admission, along with a kidney ultrasound. Follow-up ^99m Tc-DMSA took place after 6 months. Radiographic cystourethrography for VUR detection and grading was performed 1 month after the acute infection.
Results: We enrolled 70 children in the study. The kidney ultrasound failed to diagnose more than half of the cases of APN. VUR was found in 21.5% of children. 75% had findings of APN in the acute phase through ^99m Tc-DMSA, while in the second ^99m Tc-DMSA, there was a complete remission in 68% of them. Scars were observed more frequently in older children, children with VUR grade ≥ III, and children not on antibiotic prophylaxis.
Conclusion: VUR did not appear to be associated with the first episode of APN, and children older than 1 year of age had a higher risk of scarring. Antibiotic prophylaxis may prevent kidney scarring due to host immunomodulatory effects, but more studies are needed so that conclusions can be drawn.