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Background: The rate of febrile UTI recurrence and its risk factors in patients referred for pediatric urologic evaluation are not well described. We evaluated febrile UTI recurrence in this prospective longitudinal observational study.
Methods:
Consecutive patients from 2008-2012 referred with a history of febrile UTI and/or VUR underwent DMSA ≥3 months after the infection. Patients with minimum follow up of 1 month after DMSA (4 months after UTI) were included. Data including gender, age, # baseline UTIs, and ultrasound and DMSA results were prospectively recorded. Patients with obstructive or neurologic conditions and/or solitary kidney were excluded. Abnormal DMSA was defined as presence of ipsilateral diminished function <45% and/or any focal cortical uptake defects, with surgical correction of VUR recommended in patients with abnormal DMSA vs. no therapy in children with normal DMSA (i.e. continuous antibiotic prophylaxis was discontinued). Abnormal ultrasound was defined as any hydroureteronephrosis, renal cortical defects, or size asymmetry >1cm. In patients with bilateral VUR, the highest grade of VUR was used. Multiple logistic regression analyzed risk factors for recurrent febrile UTI, defined by AAP 2011 criteria (positive leukocyte esterase and ≥50k CFU bacteriuria) with fever ≥101°.
Results:
There were 602 patients (81% female) with a median age of 4.4 years (3m-18y). With average follow up 1.3 years (1m-4.7y), 119 (20%) developed a new febrile UTI. Risk factors for recurrent febrile UTI included abnormal baseline DMSA (OR 1.7, 95%CI 1.3-2.2), and ≥2 febrile and/or non-febrile UTIs at referral (OR 1.7 and 1.4, 95%CI 1.3-2.2 and 1.1-1.8, respectively). Increasing year of age was associated with lower risk for FUTI recurrence (OR 0.80, 95%CI 0.71-0.90) (AUC=0.684). Grade of VUR and baseline abnormal RUS were not independent risk factors for recurrent febrile UTI. 42/279 (15%) children with normal DMSA and a single baseline febrile UTI had recurrence vs. 34/121 (28%) with abnormal DMSA and ≥2 febrile UTIs (p=0.002).
Conclusion:
In our referral population, only a minority (20%) developed a recurrent febrile UTI during mean follow up of 1.3 years despite no antibiotic prophylaxis. Patients with a higher number of baseline UTIs, and focal cortical defects and/or diminished ipsilateral function on DMSA had higher risk for developing subsequent UTI irrespective of underlying grade of VUR. This data supports a modified top-down evaluation where delayed abnormal DMSA to and ≥2 UTIs can be used to identify patients at highest risk for recurrent febrile UTI.