Study on changes in urinary relative supersaturation and risk of stone recurrence in patients after urolithiasis...

Urolithiasis has a 50% 5-year recurrence rate. Post-operative changes in urinary relative supersaturation (RSS) may refine recurrence prediction and guide targeted interventions.

Prospective cohort of 68 stone-free adults (Jan 2023 - Jan 2024 enrollment). 24-hour urine was collected at 2 weeks, 1, 3, 6, 12 months; RSS patterns were analyzed using multivariate modeling. We used a validated food frequency questionnaire adapted for stone-forming nutrients.

radiologic and symptomatic stone recurrence; secondary: ≥30% RSS reduction ("biochemical response"). Risk scoring system developed using logistic regression probabilities. The study was approved by the institutional ethics committee with written informed consent.

At 24-month median follow-up (range 18-30), 14/68 experienced recurrence (20.6%). Independent predictors: persistently-high CaOx-RSS (OR 6.84, 95% CI 2.13-21.97), CaP-RSS > 1.5 on ≥ 2 visits (OR 4.38, 1.29-14.85), pH-reactive UA-RSS (OR 3.25, 1.04-10.18), urine volume < 1.5 L (OR 3.12, 1.21-8.03). Model performance: AUC 0.81 (95% CI 0.72-0.90); optimal threshold (p = 0.22) yielded sensitivity 0.74, specificity 0.78, PPV 0.46, NPV 0.92. RSS-guided intervention reduced recurrence versus standard care (11.8% vs. 29.4%, p = 0.027) with 44.5% absolute risk reduction in high-risk patients.

Serial RSS patterns combined with clinical variables predict recurrence with good accuracy. RSS-tailored therapy significantly reduces recurrence in high-risk patients, though implementation requires addressing feasibility and cost-effectiveness considerations.