Follow-up imaging after acute evaluations for pediatric nephrolithiasis: Trends from a National database

Overuse of computed tomography (CT) in the initial evaluation of children with upper urinary tract calculi (UUTC) has been well documented. Follow-up imaging patterns, however, remain undefined. Sequential imaging following an acute episode of UUTC represents additional opportunity for enacting good imaging stewardship, with the optimal goal to reduce unnecessary radiation exposure and cost while ensuring appropriate follow-up.

We explored nationwide imaging patterns for children following emergency department (ED) evaluations for UUTC, hypothesizing that initial imaging choice and complicated visits for UUTC increase the risk of follow-up CT scans.

Claims from Marketscan (2007-2013), an employer-based dataset of privately insured patients, were used to assess children aged 1-18 years presenting to the ED an acute UUTC event. The primary outcome was any imaging within 90 days. Using logistic regression, odds for follow-up CT or plain film kidney-ureter-bladder/ultrasound (KUB/US) imaging were calculated adjusting for patient demographics, initial imaging modality, need for admission, and return ED visits.

A total of 821 children met the inclusion criteria, of whom 261 (31.8%) received no follow-up imaging. Overall follow-up imaging patterns, including the proportions of children receiving CT scans, KUB/US imaging, or no imaging are shown in the Summary Table. Of the children receiving follow-up imaging, KUB/US was obtained in 363 (65.0%) and CT obtained in 197 (35.0%) children. Risk factors for follow-up CT imaging include hospital admission and return ED visits. Children with ureteral calculi and index US evaluation were more likely to receive KUB/US imaging only at follow-up. For children with ureteral calculi, the median time to first follow-up imaging was 9 days (25th-75th percentiles, 2-26 days).

One-third of all children with follow-up imaging after an acute presentation for UUTC will receive a CT. Up to 28% of children with a ureteral calculus will not receive any follow-up imaging within 3 months of presentation. These findings suggest imaging strategies for children following acute evaluation for nephrolithiasis are suboptimal in two ways. First, children receive potentially unnecessary additional radiation burden, an alarming finding considering the high rates of CT scan in the index evaluation for these children. Second, many children with ureteral calculi fail to receive follow-up imaging to document stone passage.

Our findings identify follow-up imaging as another area for quality improvement within the care of children with UUTC. Clinical pathways directing imaging strategies for pediatric nephrolithiasis should focus on follow-up imaging practices and initial evaluation, especially with for those children presenting with ureteral calculi.