A prospective study of recurrence rate and risk factors for recurrence after a first renal stone.

PURPOSE: We investigate further the recurrence rate and risk factors for recurrence in 300 consecutive patients who presented to our stone clinic after a first stone episode 7 to 17 years ago.

MATERIALS AND METHODS: The medical records of the patients who presented consecutively with a first stone episode from 1980 to 1990 were studied and supplemented by a followup mail questionnaire and telephone interviews. At first visit serum samples were taken from all patients and 24-hour urine samples were collected for metabolic testing.

RESULTS: A total of 195 patients were followed successfully, of whom 52 (27%) experienced symptomatic stone recurrence after a mean plus or minus standard deviation of 7.5+/-5.9 years. However, ultrasound examination of 36 symptom-free patients showed recurrent stones in 28%. Comparison of patients with or without recurrence confirmed that recurrence was not influenced by sex, family history of stones and urinary risk factors. However, age at onset of the disease was lower for patients who had 2 or more stones during followup than those who had only 1 stone or no recurrence.

CONCLUSIONS: Stones can recur as long as 10 years after the first episode, although the rate is lower than previously reported. The metabolic evaluation after a first stone episode needs to be reappraised in terms of its cost-effectiveness, since recurrences do not seem to be predictable from standard laboratory tests.