The incidence of urinary tract infections in infants with primary non-refluxing megaureter: an epidemiological evaluation of time-varying exposure analysis
Jin Kyu Kim, MD, Michael Chua, MD, MASc, Adree Khondker, BHSc, Joana Dos Santos, MD, MHSc, Margarita Chancy, MD, Kay Rivera, MD, Juliane Richter, MD, Armando Lorenzo, MD, MSc, Mandy Rickard, MN-NP.
The Hospital for Sick Children, Toronto, ON, Canada.
BACKGROUND: Primary megaureter (PM) is an entity that is separate from isolated hydronephrosis. Patients with PM have been regarded as at higher risk for developing urinary tract infections (UTI) and use of continuous antibiotic prophylaxis (CAP) in this population is common. Moreover, for boys, circumcision is often advocated to reduce the risk of UTI in the first year of life. However, there are no large epidemiological studies evaluating UTI events in this population. Herein, we aim to evaluate the risk of UTI, based on CAP use, using individualized patient data and time-varying exposure analysis.
Methods: Our institutional PM database was examined. PM defined as hydroureteronephrosis with dilatation > 7mm. We excluded patients with other etiologies for upper tract dilatation. UTI was defined as fever >38.5°C, with positive urinalysis and culture from catheterized specimens. Only UTIs within the first year of life were included. To adjust for time-varying exposure, patients were censored based on CAP discontinuation, UTI event, surgery, loss to follow-up, or hydroureter resolution. Survival analysis was performed.
Results: A total of 195 patients with PM were identified. Of these, 154 (84.1%) were boys, with 71 (46.1%) of them circumcised. The UTI rates were highest among non-circumcised boys (13/157, 8.3%) compared to circumcised (0/8, 0.0%), and female patients (3/30, 10.0%). Other baseline characteristics were similar across the three groups, including age at presentation, antenatal diagnosis, laterality, SFU grading, and maximal ureteral dilation (Table 1). Kaplan-Meier survival curve, accounting for time-varying exposure censoring, showed a split of the curve between patients with and without CAP exposure (log-rank p=0.072). All of the events in both CAP and no CAP exposure groups occurred early, within the first 30 days of life and curves became parallel with a limited occurrence of UTIs after (Figure 1).
CONCLUSIONS:
The rate of UTI is the highest in the first month of life for both CAP and no CAP patients. Although not statistically significant, our Kaplan-Meier survival curve shows that CAP is likely to have a protective effect for UTI and should be considered for use in patients with megaureters. While numbers are small, those who were circumcised did not have any UTI. Nonetheless, the duration of CAP use likely does not need to be prolonged as the UTI rates were similar between those with and without CAP exposure after the first month of life.
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