BACKGROUND: Optimum management to prevent recurrent kidney stones is uncertain.
PURPOSE: To evaluate the benefits and harms of interventions to prevent 
recurrent kidney stones.
DATA SOURCES: MEDLINE, Cochrane, and other databases through September 2012 and 
reference lists of systematic reviews and randomized, controlled trials (RCTs).
STUDY SELECTION: 28 English-language RCTs that studied treatments to prevent 
recurrent kidney stones and reported stone outcomes.
DATA EXTRACTION: One reviewer extracted data, a second checked accuracy, and 2 
independently rated quality and graded strength of evidence.
DATA SYNTHESIS: In patients with 1 past calcium stone, low-strength evidence 
showed that increased fluid intake halved recurrent composite stone risk 
compared with no treatment (relative risk [RR], 0.45 [95% CI, 0.24 to 0.84]). 
Low-strength evidence showed that reducing soft-drink consumption decreased 
recurrent symptomatic stone risk (RR, 0.83 [CI, 0.71 to 0.98]). In patients with 
multiple past calcium stones, most of whom were receiving increased fluid 
intake, moderate-strength evidence showed that thiazides (RR, 0.52 [CI, 0.39 to 
0.69]), citrates (RR, 0.25 [CI, 0.14 to 0.44]), and allopurinol (RR, 0.59 [CI, 
0.42 to 0.84]) each further reduced composite stone recurrence risk compared 
with placebo or control, although the benefit from allopurinol seemed limited to 
patients with baseline hyperuricemia or hyperuricosuria. Other baseline 
biochemistry measures did not allow prediction of treatment efficacy. 
Low-strength evidence showed that neither citrate nor allopurinol combined with 
thiazide was superior to thiazide alone. There were few withdrawals among 
patients with increased fluid intake, many among those with other dietary 
interventions and more among those who received thiazide and citrate than among 
control patients. Reporting of adverse events was poor.
LIMITATIONS: Most trial participants had idiopathic calcium stones. Nearly all 
studies reported a composite (including asymptomatic) stone recurrence outcome.
CONCLUSION: In patients with 1 past calcium stone, increased fluid intake 
reduced recurrence risk. In patients with multiple past calcium stones, addition 
of thiazide, citrate, or allopurinol further reduced risk.
PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.