A systematic review published in the Annals of Internal Medicine evaluated the effectiveness of interventions to prevent the recurrence of nephrolithiasis or kidney stones. Across 31 studies including more than 30,000 participants, researchers found pharmacologic strategies that may reduce the risk for new stones, along with dietary interventions showing favorable but limited effects. This review also raises caution regarding the use of lemon juice.

The analysis included 26 randomized clinical trials and five nonrandomized studies assessing preventive interventions in adults and children with a history of kidney stones. Researchers assessed the strength of evidence using criteria from the Agency for Healthcare Research and Quality, which funded the study along with the Patient Centered Outcomes Research Institute. Approximately half of the studies were conducted in the US, with the remainder conducted in Europe or Asia. Only three studies included pediatric populations, and the findings were inconclusive. Most of the studies had a high risk for bias.

Seventeen randomized studies and six nonrandomized studies evaluated pharmacologic interventions. Researchers have concluded that thiazides, allopurinol, acetohydroxamic acid, and alkalinizing agents may prevent stone recurrence.

Drug Options

Evidence from three randomized trials showed that thiazide diuretics may provide at least a small benefit for the risk for recurrence or regrowth of mixed stones, although the strength of the evidence is low. Two randomized studies provided limited evidence that allopurinol may offer a benefit to reduce the risk for recurrence or regrowth of mixed stones in adults with at least one stone predominantly composed of calcium oxalate.

In two randomized studies enrolling adults with infection-related stones, acetohydroxamic acid showed benefits compared with placebo in reducing the risk for stone growth, but adverse events increased.

Two randomized trials suggested that alkalinizing therapy with citrate salts may reduce the risk for recurrence or growth of mixed stones in adults with stones having at least 50% calcium oxalate.

One Italian randomized study in individuals with recurrent idiopathic calcium oxalate nephrolithiasis found that lemon juice used as an alkalinizing agent reduced the risk for recurrence or growth of mixed stones. However, it was associated with at least a small risk for adverse events. Gastrointestinal symptoms were more frequent among individuals taking lemon juice (60 mL twice daily), and the benefits declined over time, likely due to a progressive decline in adherence.

Diet Measures

Seven randomized studies assessed dietary interventions, including fluid intake, consumption of soft drinks, and nutritional strategies. Because of heterogeneity, the results could not be pooled. The only interventions supported by sufficient evidence, although still with limited evidence, were increased fluid intake and a diet with normal or high calcium, low protein, and low sodium.

In one Italian randomized study of individuals with calcium oxalate or phosphate stones, increasing fluid intake to achieve a urine volume of at least 2 L/d reduced the risk for recurrence of mixed stones compared with no treatment.

Another Italian randomized study in men with idiopathic hypercalciuria and recurrent calcium oxalate stones found that a diet with normal or high calcium, low protein, and low sodium reduced the risk for recurrence of mixed stones compared with a low calcium diet.

Three dietary interventions previously classified in a 2012 report as having evidence of efficacy — reduced consumption of sugary beverages, a low-protein high-fiber diet, and individualized diets based on baseline metabolic testing — were downgraded to interventions with insufficient evidence of efficacy. Evidence for other interventions, including consumption of mineral water or reduced intake of soft drinks, was also not considered beneficial, largely because of the study limitations.

“It is largely uncertain whether other pharmacologic or dietary interventions prevent recurrent symptomatic stones. Evidence on harms either is insufficient or shows no harms for most that other pharmacologic or dietary interventions are unlikely to prevent the recurrence of symptomatic stones,” the authors concluded.

This story was translated from Univadis Italy, part of the Medscape Professional Network.