Randy Dotinga is a medical writer based in San Diego, Calif.
A large new study provides more evidence that cholesterol drugs may lower kidney stone formation.
A large new study provides more evidence that cholesterol drugs may lower kidney stone formation. Researchers found that subjects who took statins were less likely to develop stones, and they spotted an especially dramatic effect among recurrent stone formers.
The findings don’t say anything about a direct link between statins and stone formation, so there’s no way to know if cholesterol drugs hold value as a preventive measure for patients at risk of stones. “For now, patients with stones who are already on statins should be encouraged to continue use,” said lead author Andrew Cohen, MD, a urology resident at the University of Chicago Medical Center.
At issue: Are statins beneficial for those at risk of stones? There’s sparse research into the question.
A 2013 study of military medical records (Clin Nephrol 2013; 79:351-5) found fewer cases of stone formation in patients who took statin medications compared to those who did not (3.1% vs. 3.7%, univariate OR=0.83, 95% CI: 0.76-0.91, p<.001), and multivariate analysis suggested a protective effect for statins (OR=0.51, 95% CI: 0.46-0.57, p<.001). And a newer study (Urolithiasis 2015; 43: 49–53) of more than 52,000 subjects linked dyslipidemia to a higher rate of kidney stones in both univariate (HR=2.2 [CI: 1.9–2.5; p<.001]) and multivariate (HR=1.2 [CI: 1.0–1.5; p=.033]) analysis.
For the current study, presented at the 2016 AUA annual meeting in San Diego, the authors identified 101,259 patients diagnosed with hyperlipidemia during enrollment at the University of Chicago Medical Center from 2009-2011. Researchers tracked the subjects for stone formation and cholesterol drug use through 2015.
Almost 48% received a prescription for a statin in the study period; they were much older (60.7 vs. 51.9 years) and more obese (29.2 kg/m2 vs. 28.1 kg/m2, both p<.01).
Those who took statins and hadn’t had stones previously were less likely than non-users to develop new stones (3.8% vs. 4.7%, p<.01).
After adjusting for race, body mass index, gender, and comorbidities, the authors found evidence of a protective effect of statins (OR=0.57, p<.01), and the apparent effect was greatest in previous stone formers (OR=0.53, p<.01).
Is lower cholesterol translating to fewer stones? Dr. Cohen doesn’t think so.
“Our inclusion of lipid lab data suggests patients prescribed statins were compliant with their medication. But there was no clinically significant association between high total cholesterol or high LDL cholesterol levels and stone risk. This may mean statins function via reducing inflammation and not by direct lipid-lowering effects,” said Dr. Cohen, who worked on the study with Sangtae Park, MD, MPH, and colleagues.
How might there be a connection then?
“Statin-treated rats have been shown to have lower levels of renal tubular cell injury and increased antioxidants, but more research is needed to understand the biology of this association. Statins may have wide-reaching effects within the body that are not completely understood,” Dr. Cohen said.
What should happen next?
“Future study involving concurrent 24-hour urine parameters and stone analysis for those patients on statin therapy may be of benefit,” Dr. Cohen said. “Furthermore, if an anti-inflammatory effect is truly the cause, the utility of other anti-inflammatory medications could be studied in this context. A prospective randomized clinical trial would be definitive.”