Predictors of recurrence and renal scarring post-urinary tract infection among young febrile infants.

BACKGROUND

Urinary tract infections (UTIs) among infants ≤ 3 months old are associated with a high risk of recurrence and renal scarring, yet evidence identifying high-risk infants remains limited. We aimed to identify predictors of UTI recurrence and factors associated with renal scarring in this population.

METHODS

A retrospective chart review was conducted on febrile infants ≤ 3 months at a tertiary paediatric hospital in Singapore, between January 2018 and June 2023. We defined recurrence as any episode occurring within 1 year of the index UTI and renal scarring based on the Technetium-99 m 2,3-dimercapto-succinic-acid (DMSA) scan. Multivariable logistic regression was performed to predict for UTI recurrence and renal scarring, using covariates selected a priori. We presented the adjusted odds ratio (aOR) with corresponding 95% confidence interval (95%CI).

RESULTS

Among 401 infants (median age: 49 days [28-70]; 76% male), 49 (12.2%) experienced recurrent UTI. Male sex (aOR = 2.80, 95%CI:1.14-8.46, p = 0.041) and ultrasound kidney, ureter, and bladder (US KUB) abnormalities (aOR = 2.72, 95%CI:1.40-5.27, p < 0.05) independently predicted recurrence. Among 161 infants with DMSA performed, 21 (13.0%) developed renal scarring. Scarring was associated with bacteraemia (OR = 4.38, 1.54-12.05, p < 0.05), elevated procalcitonin ≥ 0.5 ug/L (OR = 16.82, 4.53-109.39, p < 0.001), non-E.coli uropathogen (OR = 6.18, 2.37-17.49, p < 0.001), hydronephrosis (OR = 3.04, 1.17-7.87, p < 0.05), and vesicoureteral reflux (VUR) (OR = 18.70, 4.31-133.32, p < 0.001), particularly high-grade severity ≥ 3 (OR = 25.50, 5.74-185.47, p < 0.001). Additionally, multivariable analysis identified US KUB abnormalities (aOR = 3.00, 1.57-5.73, p < 0.001) as an independent predictor of renal scarring.

CONCLUSION

We reported independent predictors of UTI recurrence and risk factors for renal scarring. These patients should receive more intensive monitoring after their index UTI.