Nephrolithiasis is a frequent condition. It is generally accepted that this condition carries a risk of recurrence after the first episode, however the exact risk has been rarely quantitated. The aim of this study was to analyze randomized controlled trials (RCTs) of calcium stone formers to estimate overall rate of recurrence and in specific subgroups.
Design and setting: Systematic review with meta-analysis of randomized controlled trials of patients with calcium kidney stones.
Participants: Adults with at least one kidney stones episode enrolled in parallel-arms, randomized controlled trials aimed at evaluating stone recurrence.
Intervention: No intervention/placebo, dietary changes, drug interventions.
Measurements: Rate of recurrence of kidney stones.
The analysis included 21 studies with 2,168 participants over a median follow-up of 3 years. The rate of recurrence of kidney stones was 5.9 (95% CI 2.9, 8.8) per 100 person-years in those with a single stone episode and 22 (95% CI 8.4, 36) in those with two or more stone episodes. Rates decreased slightly but significantly over time. The effect of treatment groups depended on previous stone history: in RCTs that enrolled patients with a single stone episode, diet was more effective than drugs compared with placebo or no intervention; in those with two or more stone episodes, drugs were more effective than diet compared with placebo or no intervention. Average age was significantly associated with recurrence, whereas proportion of males was not.
The overall recurrence rate of stones depends on factors such as previous stone history and treatment modality. Dietary approaches seem to be more effective among patients at their first stone episode, whereas drugs seem to be more effective among those with recurrent disease.
