Nephrolithiasis management and outcomes in pediatric patients with limited mobility.

Introduction And Objectives: Pediatric patients with limited lower extremity mobility may be at increased risk of developing nephrolithiasis due to bone mineral metabolic derangements. This study sought to assess whether nephrolithiasis management and related outcomes differ between ambulatory versus non-ambulatory pediatric patients.

Methods: This was a retrospective review of ambulatory and non-ambulatory pediatric patients with nephrolithiasis from 2010 to 2021 from a single tertiary care center. Demographics, surgical history, stone compositions, and 24-h urine data were reviewed. Adjusted logistic and linear regression models were utilized to assess whether mobility status was associated with nephrolithiasis-related management and outcomes, including: age at first stone; requiring surgical intervention for stones; number of surgeries; stone compositions; urine culture results; and completion of 24-h urine studies.

Results: Among 339 pediatric patients with nephrolithiasis, 67 (19.8%) were non-ambulatory. In adjusted analyses, non-ambulatory patients had 3.24 times greater odds of requiring surgical intervention for stones (95% CI: 1.93-6.84; p < 0.0001); among those who required surgery, non-ambulatory patients required an average of 0.82 more surgical interventions (95% CI: 0.35-1.30; p = 0.0008) than ambulatory patients. Additionally, non-ambulatory patients had 5.28 times greater odds of having a positive urine culture at the time of surgery (95% CI: 2.35-14.08; p = 0.0001) and were significantly less likely to undergo 24-h urine studies (OR: 0.35; 95% CI: 0.15-0.83; p = 0.02). Stone composition significantly varied by mobility status, with non-ambulatory patients being significantly more likely to form calcium apatite (OR: 5.1; 95% CI: 2.18-11.93; p = 0.0002) or struvite (OR 3.72; 95% CI: 1.18-11.74; p = 0.03) stones, and significantly less likely to form calcium oxalate stones (OR: 0.19; 95 CI: 0.08-0.47; p = 0.0003). Among all patients, age at first stone occurred at a median age of 13.4 years (IQR: 8.2-16.4) and did not significantly differ by mobility status (p = 0.92).

Conclusions: Patients with limited mobility required surgery for nephrolithiasis at significantly higher rates and had different stone compositions than ambulatory patients. Obtaining a 24-h urine study in patients with comorbidities affecting ambulation was uncommon, compared to ambulatory patients. Similarly to ambulatory patients, pediatric patients with limited mobility who develop nephrolithiasis tend to first present with stones in early adolescence.