Kidney Stones and Cardiovascular Risk: A Meta-analysis of Cohort Studies

Background: Recent epidemiologic evidence suggests an association between kidney stones and incident cardiovascular disease after adjusting for other cardiovascular risk factors, but results are inconsistent. Study Design: Meta-analysis of cohort studies. Setting & Population: Patients with kidney stones. Selection Criteria for Studies: Cohort studies with data for kidney stones and cardiovascular morbidity identified in PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and conference proceedings through February 27, 2014. Predictor: Kidney stones as determined by physician diagnosis, clinical coding, or self-reported scales. Outcomes: Cardiovascular disease, coronary heart disease (CHD), and stroke. Results: 6 cohort studies that contained 49,597 patients with kidney stones and 3,558,053 controls, with 133,589 cardiovascular events, were included. Pooled results suggested that kidney stones were associated with an increased adjusted risk estimate for CHD (HR, 1.19; 95% CI, 1.05-1.35; P = 0.05; n = 6 cohorts) and stroke (HR, 1.40; 95% CI, 1.20-1.64; P < 0.001; n = 3 cohorts). In particular, kidney stones conferred HRs of 1.29 (95% CI, 1.10-1.52; n = 6 cohorts) and 1.31 (95% CI, 1.05-1.65; n = 4 cohorts) for myocardial infarction and coronary revascularization, respectively. Moreover, the pooled female cohorts showed a statistically significant association (HR, 1.49; 95% CI, 1.21-1.82; n = 4 cohorts), whereas the male cohorts showed no association (HR, 1.15; 95% CI, 0.89-1.50; n = 2 cohorts). Limitations: Results may be limited by substantial heterogeneity, likelihood of residual confounding, and paucity of studies that separately evaluated for effect modification by sex. Conclusions: Kidney stones were associated with increased cardiovascular risk, including the risk for incident CHD or stroke. There is some suggestion that the risk may be higher in women than men. Further prospective studies are needed to determine whether the association is sex specific. (C) 2014 by the National Kidney Foundation, Inc.