Predicting Factors for Recurrence in First-time Stone Formers

Abstract

Purpose: The purpose of the present study was to determine the risk factors for predicting the recurrence in first-time urinary stone formers. Materials and Methods: A total of 121 patients, who presented at our hospital with first-time urinary stone episodes, between 1996 and 2005, and followed up for at least 3 years, were retrospectively evaluated. Of these, 65 patients (41 males, 24 females) recurred (R group) and 56 (38 males, 18 females) not (NR group) during the follow-up period. The blood chemistry and urinary analytes values, as well as the clinical characteristics between the NR and R groups were compared by gender. p-values less than 0.05 were used to indicate statistical significance. Results: There were no differences in the clinical characteristics between the NR and R groups. A comparison of the blood chemistry showed differences in the phosphate and calcium in men and women (p=0.047 and 0.034), respectively. Greater urinary excretion of phosphates were found in the R group than in the NR group (p=0.018), but was more prominent in men (p=0.006). No significant differences were found between the two groups with regard to metabolic abnormalities. A multivariate analysis revealed that urinary phosphates excretion was the sole predictor for stone recurrence (Exp β=8.347, p=0.033). Conclusions: Our results suggested that the increased excretion of urinary phosphates was a significant risk factor for stone recurrence, which might be useful as a prognostic marker. (Korean J Urol 2007;48:176-182)