Development of metaphylaxis in calcium urolithiasis: a restriction of conventional drug therapy

Between 1978 and 1992 (mean 9.2 years), metaphylaxis was introduced to 110 patients originally hospitalized for recurrent urinary calcium stones (mostly bilateral or multiple). Patients with hyperparathyroidism or with sponge kidney were excluded from the study. Until 1984, the condition had been treated mostly using conventional drug metaphylaxis (thiazides and allopurinol in 75% and 57%, respectively). After that year, there was a gradual decrease in the number of patients treated with thiazides (to 15%) and allopurinol (to 10%). This was associated with a steep rise in the proportion of patients treated with inhibitors (magnesium to 36% and citrates to 30%), or exclusively with non-medicamentous therapy (to 31%). These fundamental changes in approach have not reduced the effectiveness of metaphylaxis, and recurrence rates in individual years have not changed significantly either. Metaphylaxis was successful in 105 patients (95%) and the rate of recurrence has declined from 0.9 to 0.08 stones per year. The restriction of conventional drug metaphylaxis has entailed a marked decrease in the incidence of side effects of therapy and, consequently, a reduced need for follow-up tests and outpatient follow-up.