Review – Stone DiseaseDiet, Fluid, or Supplements for Secondary Prevention of Nephrolithiasis: A Systematic Review and Meta-Analysis of Randomized Trials
Introduction
The lifetime prevalence of nephrolithiasis has been estimated at 13% among men and at 7% among women [1], [2], with conflicting data regarding whether prevalence is increasing [1], [2], [3]. Although stones may be asymptomatic, potential consequences include renal colic, urinary tract obstruction, infection, hospitalizations, and procedure-related morbidity. Following an initial stone event, the spontaneous 5-yr recurrence rate is 35–50% [4].
In large observational studies, several modifiable factors have been associated with increased risk of nephrolithiasis, including low fluid intake, low dietary calcium, and low dietary potassium, while results for diets with increased animal protein and increased sodium have been mixed [5], [6]. Although a number of trials have evaluated the efficacy of diet, fluid, or supplement interventions in reducing risk of recurrence, few have been included in previous systematic reviews [7], [8] or have been referenced in recent nephrolithiasis management guidelines [9], [10]. Therefore, we conducted this systematic review and meta-analysis to clarify the evidence on the benefits and the adverse effects of diet, fluids, and supplement treatments for secondary prevention of nephrolithiasis.
Section snippets
Literature search
We searched Medline (January 1950 to March 2008) using the following terms: urolithiasis and (controlled clinical trial or randomized clinical trial or randomized controlled trial or systematic reviews or meta-analysis). Bibliographies of retrieved trials and review articles also were examined.
Selection criteria
A trial was eligible for inclusion if it met the following criteria: (1) it was composed of community-dwelling participants aged ≥18 yr with at least one prior resolved episode of renal colic; (2) it was
Study selection
We identified 579 citations via our Medline search. After review of titles and abstracts, we retrieved 28 articles for detailed review, of which 8 met inclusion criteria. No additional references identified from bibliographies of retrieved trials and review articles met inclusion criteria.
Trial characteristics
Eight trials of diet [13], [14], [15], [16], [17], [18] or supplement interventions [19], [20] met eligibility criteria and were included in this review (1855 total participants; number of participants per
Conclusions
Our systematic review of randomized controlled trials (RCTs) found that high water intake lowered long-term risk of nephrolithiasis recurrence by approximately 60% and that among men with high baseline soft drink intake, reduced soft drink consumption modestly lowered risk of recurrent renal colic. Results from one trial suggested that when added to increased water intake, a diet including higher calcium, lower animal protein, and lower sodium reduced stone risk compared with a low-calcium
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