Time to Nephrolithiasis Diagnosis in Pediatric Patients with Limited Mobility
Arthi Hannallah, MD, Zoë G. Baker, PhD, MPH, Thalia Bajakian MD, Nadine Khouzam, MD, S. Scott Sparks, MD.
Children's Hospital Los Angeles, Los Angeles, CA, USA.
BACKGROUND: Pediatric patients with conditions associated with limited lower extremity mobility may develop nephrolithiasis due to bone mineral metabolic derangements. This study sought to determine when pediatric patients with limited mobility would develop nephrolithiasis, and if such patients would have higher intervention rates than pediatric patients who are ambulatory.
METHODS: This was a retrospective review of pediatric patients with nephrolithiasis from 2010-2021 from a single tertiary care center. Demographics, surgical history, stone compositions, and 24-hour urine data were reviewed. Metabolic evaluation and surgery rates were compared between two cohorts with nephrolithiasis: patients with limited mobility and patients who are ambulatory. Pearson X2 and t-tests were used to assess associations between number of surgeries, undergoing a 24-hour urine study, and patient cohort. Time to initial stone event in patients with limited mobility was determined via Kaplan-Meier analysis.
RESULTS: Among 348 pediatric patients with nephrolithiasis, 77 (22.1%) had limited mobility. The most common diagnoses were cerebral palsy (n=27, 35.1%), spina bifida (n=15, 19.5%), and cerebral/spinal injury (n=5, 6.5%). Eight patients (10.4%) with limited mobility had 24-hour urine studies completed, compared to 20.7% of ambulatory patients (p=0.04). Overall, 53 patients (68.8%) with limited mobility underwent surgery for stones, which was significantly higher than ambulatory patients undergoing surgery for stones (44.3%, p=0.001). Among patients with limited mobility, median age at first stone episode was 12.1 years, which was not significantly different from age at first stone among ambulatory patients (IQR: 8.6-15.8; Figure 1).
CONCLUSIONS: Median time to developing a stone event in pediatric patients with limited mobility is 12.1 years. Patients with limited mobility require surgery significantly more often than ambulatory patients. Obtaining a 24-hour urine study in patients with significant comorbidities was relatively uncommon and did not alter the need for surgery. Providers for pediatric patients who limited mobility due to significant comorbidities may need to consider imaging evaluation to screen for renal stone disease in early adolescence. 
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