Impact of statins on nephrolithiasis in hyperlipidemic patients: a 10-year review of an equal access health care system

Aim. To investigate the impact of statin medications on urinary stone formation in hyperlipidemic patients. Material and methods: We searched outpatient military electronic health records from the Southwestern United States to identify adult patients with hyperlipidemia and urolithiasis. Military facilities serve active duty members, retirees, and their immediate family members. We created two predictor variables - with and without statin. The outcome variable was a diagnosis of urolithiasis. Results: The inception cohort included 57,232 subjects with hyperlipidemia and 1,904 subjects with nephrolithiasis. Patients taking statin medications had significantly less stone formation compared to patients not taking statin medications (3.1% vs. 3.7%, univariate OR = 0.83, 95% CI 0.76 - 0.91, p < 0.001). Statins patients were significantly older (59 vs. 45 years, p < 0.001), more likely to be female (38% vs. 34%, p < 0.001) and have co-morbidities (obesity, hypertension, diabetes, heart disease; all p < 0.001). Multivariate analysis indicated that statin medications had a protective effect against stone formation (OR = 0.51, 95% CI 0.46 - 0.57, p < 0.001), after adjusting for age, sex, and comorbidities. The risk of nephrolithiasis was not only additive for diabetes mellitus, hypertension, and obesity; more importantly it was attenuated with addition of statin use. Conclusion: Statin medications are associated with reduced risk of urinary stones. This is the first study to demonstrate the impact of statins on nephrolithiasis. Further prospective studies are necessary to validate these findings that treatment of hyperlipidemia reduces stone risk formation.