A prospective study of nonmedical prophylaxis after a first kidney stone

Abstract

Objective: To assess, in a multicentre prospective randomized study, the effectiveness of specific nonmedical prophylaxis and nonspecific dietary prophylaxis in patients treated after experiencing their first idiopathic calcium-containing kidney stone.

Patients and methods: From 1991 to 1994, 242 patients with idiopathic calcium urinary stones from three urological centres were randomly assigned into two groups. In group 1 (intervention, 113 patients), a specific dietary regimen was recommended and thereafter corrected according to a comprehensive metabolic evaluation. Group 2 (control, 94 patients) underwent only minimal metabolic screening and used general dietary measures, with no regular follow-up. An increased fluid intake was recommended in both groups. After 3 years, the effectiveness of the prophylactic and dietary regimens was evaluated in 207 patients.

Results: At entry, the clinical characteristics were comparable in the two groups, with only extracorporeal lithotripsy being more frequent in group 2. Almost 80% of patients reported a high intake of meat and a low intake of dairy products. In group 1 and 2, a recurrent stone was encountered in seven (6%) and 18 (19%) patients, respectively; recurrent and growing stones were found in eight (8%) and 22 (23%) patients, respectively (P<0. 01). There was a higher incidence of bilateral residual (or untreated) stones, and Weddellite stones (P<0.001) among patients with a recurrent or growing stone. An analysis of the dynamics of the metabolic variables indicated the significance of repeated dietary counselling.

Conclusion: Specific dietary therapy, adjusted according to a metabolic evaluation, is more effective than nonspecific general dietary recommendations in preventing the formation of a second urinary stone.