Abstract
PURPOSE: We aimed to determine the influence of nutritional status on urinary metabolic abnormalities and stone recurrence in patients with urolithiasis. MATERIALS AND METHODS: We analyzed data for 464 stone-formers and 464 propensity-score-matched control patients that had been collected between 2003 and 2015. Nutritional status was evaluated by use of the Controlling Nutritional Status (CONUT) score, and patients were placed into two CONUT score categories (0-1 and ≥2). Serum and 24-hour urinary metabolites were evaluated in 464 stone-formers. Kaplan-Meier and multivariate Cox regression analyses were performed to assess the influence of nutritional status on stone recurrence. Stone recurrence was defined as radiographic appearance of new stones during the follow-up period. RESULTS: Stone-formers showed a higher prevalence of poor nutrition (CONUT score ≥2) than did the propensity-score-matched control patients (p<0.001). Stone-formers who had poor nutritional status had significantly lower 24-hour urinary calcium but higher oxalate excretion (each p<0.05). Kaplan-Meier estimates demonstrated that stone-formers with poor nutritional status also experienced stone recurrence more rapidly (log-rank test, p=0.014). Multivariate Cox regression revealed that poor nutritional status was independently associated with stone recurrence (hazard ratio, 1.736; 95% confidence interval, 1.041-2.896; p=0.034). CONCLUSIONS: The CONUT score, an easily measured immunonutritional biomarker, is independently associated with a higher risk for stone recurrence in patients with urolithiasis. This implies that not only dietary excess, but also undernourished status, may be associated with aberrations in urine physicochemistry and stone recurrence.