Utilization of Radiographic Imaging for Infant Hydronephrosis over the First 12 Months of Life.

Purpose: The workup and surveillance strategies for infant hydronephrosis (HN) vary, although this could be due to grade-dependent differences in imaging intensity. We aimed to describe the frequency of imaging studies for HN within the first year of life, stratified by initial HN grade, within a large regional healthcare system. Study Design and Data Source. Retrospective cohort using Intermountain Healthcare Data Warehouse. Inclusion criteria: (1) birth between 1/1/2005 and 12/31/2013, (2) CPT code for HN, and (3) ultrasound (U/S) confirmed HN within four months of birth. Data Collection. Grade of HN on initial postnatal U/S; number of HN-associated radiologic studies (renal U/Ss, voiding cystourethrograms (VCUGs), and diuretic renal scans); demographic and medical variables. Primary Outcome. Sum of radiologic studies within the first year of life or prior to pyeloplasty. Statistical Analysis. Multivariate poisson regression to analyze association between the primary outcome and the initial HN grade.

Results: Of 1,380 subjects (993 males and 387 females), 990 (72%), 230 (17%), and 160 (12%) had mild, moderate, and severe HN, respectively. Compared with those with mild HN, patients with moderate (RR: 1.57; 95% CI: 1.42-1.73) and severe (RR: 2.09; 95% CI: 1.88-2.32) HN had a significantly higher rate of imaging use over 12 months (or prior to surgery) after controlling for potential confounders.

Conclusions: In a large regional healthcare system, imaging use for HN is proportional to its initial grade. This suggests that within our system, clinicians treating this condition are using a risk-stratified approach to imaging.