Oral antibiotic exposure and the risk of overweight and obesity in children with vesicoureteral reflux.

BACKGROUND

Continuous antibiotic prophylaxis (CAP) is widely used in children with vesicoureteral reflux (VUR) to prevent recurrent urinary tract infections, but its long-term metabolic effects are uncertain. We evaluated whether oral antibiotic exposure is associated with overweight and obesity in young children with VUR.

METHODS

Using the TriNetX Research Network, we conducted a retrospective cohort study of children aged <5 years diagnosed with VUR between 2005 and 2025. Patients were classified as antibiotic-exposed or unexposed based on prescription patterns, and propensity score matching balanced baseline covariates. Overweight and obesity were defined using body mass index (BMI) percentiles and diagnosis codes. We performed U.S.-only sensitivity and age-stratified analyses (<1 year; 1-4 years) and calculated the number needed to harm (NNH).

RESULTS

After matching, 2665 patients were included per group. In the primary cohort aged <5 years, BMI percentile-defined overweight and obesity occurred in 60 (2.3 %) of antibiotic-exposed patients and 21 (0.8 %) of unexposed patients (hazard ratio [HR], 3.25; 95 % confidence interval [CI], 1.97-5.34; log-rank p < 0.001). Results were similar using diagnosis code-based definitions (1.3 % vs. 0.6 %; HR, 2.30; 95 % CI, 1.27-4.17; log-rank p = 0.005). Associations persisted in U.S.-only analyses and were stronger in children aged <1 year. The NNH for BMI-defined overweight/obesity was 69.

CONCLUSIONS

Early oral antibiotic exposure in children with VUR was significantly associated with increased risk of overweight and obesity. However, given the low absolute number of events, these findings should be interpreted cautiously and weighed against the potential benefits of CAP.