Prospective study on the efficacy of a selective treatment and risk factors for relapse in recurrent calcium oxalate stone patients.

OBJECTIVE: The present study was performed to examine the efficacy of a selective treatment according to the guidelines for the prevention of recurrence in calcium oxalate stone patients and to assess risk factors for stone recurrence.
METHODS: To investigate the effect of specific diagnostic and therapeutic measures, 134 recurrent calcium oxalate stone formers participated in a prospective study for two years with regular follow-ups of at least every six months. Depending on the results of analysis of 24-hour urine, nutrition record and metabolic situation, selective recommendations were given concerning diet and medication.
RESULTS: Throughout the follow-up period, 57 (43%) of the patients experienced relapses. In recurrence-free patients, the significant increase in urinary volume, as well as urinary pH, potassium and citrate excretion, three indexes of compliance with alkalization, resulted in a significant decrease in the calculated risk of calcium oxalate stone formation. In patients with recurrences during follow-up, the relative supersaturation with calcium oxalate increased significantly, mainly due to the significant rise in urinary oxalate excretion exceeding the significant increases in urinary volume, pH, potassium and citrate excretion. Multiple logistic regression analysis revealed previous ESWL treatment and a history of multiple stones as independent predictors of the risk for recurrence.
CONCLUSIONS: The results indicate that compliance with drinking advice and alkalization therapy was highest among both, patients with and without recurrences, compared with all other therapeutic measures. The increase in oxalate excretion is identified as the major urinary risk factor for relapse during follow-up in recurrent calcium oxalate stone disease.