According to a recent systematic review (SR) that evaluated the role of AP as a preventive measure against UTIs in infants with AHN, AP use was shown to reduce the rate of UTIs in patients with grade III-IV hydronephrosis. Unfortunately, due to limitations in the available SR data, the effect of gender and circumcision status could not be properly evaluated. Herein we sought to analyze a single-center experience to further explore the impact of these unmeasured variables in this population.
A comprehensive AHN database including all neonates scheduled to undergo a voiding cystogram (VCUG) between 2005 and 2012 was reviewed. Patients in whom VCUG was not properly completed (n=126) were excluded. The primary outcome was development of a febrile UTI (fUTI). Five a priori defined risk factors were explored: ANH grade [low (I-II) vs. high (III-IV)], AP use, presence of VUR, gender, and circumcision status. These were subjected to univariate and multivariable regression, with log-rank and stratified analyses conducted to corroborate findings, while adjusting for differences in follow-up time.
Data on 1040 patients (72% males) with a mean follow-up of 27.7 months were available for review. VUR was detected in 241 (23%) and was bilateral in 149 (14%). AP was prescribed for 463/1040 (44.5%), including 193/241 (80%) of patients with VUR and 270/799 (34%) of those without. Neonatal circumcision was carried out in 140/749 (19%) of males. A total of 221 patients presented with a fUTI. Of the explored risk factors, female gender and uncircumcised boys (HR circumcised males vs. uncircumcised males and all females = -1.04, 95%CI=-1.9to-0.4;p=0.006), and lack of AP (HR no use vs. use =1.4, 95%CI=1.1to1.7; p=0.001) were associated with a higher rate of fUTIs. However, the protective effects of circumcision and AP were more evident in high-grade hydronephrosis (figure), with protection conferred to uncircumcised males and females on AP, and circumcised males regardless of AP. On multivariable regression analysis, use of AP (p<0.01), grade III-IV AHN (p<0.01), presence of reflux (p<0.01) and gender (p=0.03) all remained statistically significant.
Our findings support the role of hydronephrosis grade as a risk factor for fUTIs in children with ANH. AP appears to selectively decrease the risk of infections in females and uncircumcised males with high grade hydronephrosis. Circumcised males are at low risk for fUTIs irrespective of other risk factors. These findings provide evidence for selective use of AP and highlight the need for properly powered prospective randomized studies.