Renal dysfunction and risk of ischemic stroke or TIA in patients with cardiovascular disease

Background: Mild renal insufficiency is increasingly recognized as an independent risk factor for cardiovascular disease. However, few data exist regarding its relation to risk of ischemic stroke. Methods: Patients with chronic coronary heart disease and measured serum creatinine levels (n = 6,685) were followed up for incident ischemic stroke or TIA over 4.8 to 8.1 years. Glomerular filtration rate was estimated by the Cockroft-Gault equation and by the four-component Modification of Diet in Renal Disease (MDRD) equation and a rate <= 60 mL/minute/1.73 m(2) defined chronic kidney disease ( CKD). Results: Among 6,685 patients, a quarter of patients had CKD. Adjusting for conventional risk factors and related medications, patients with CKD exhibited 1.54-fold hazard ratios (95% CI 1.13 to 2.09) of incident ischemic stroke or TIA by the Cockroft-Gault equation (1.53; 95% CI 1.16 to 2.01 by the MDRD equation). The corresponding adjusted hazard ratio associated with an increment of 1 SD in GFR was 0.71 ( 95% CI 0.57 to 0.88) when estimated by the Cockroft-Gault equation (0.84; 95% CI 0.75 to 0.95 estimated by the MDRD equation). Conclusions: Mild degrees of renal dysfunction are associated with increased risk of incident ischemic stroke or TIA in patients with pre-existing atherothrombotic disease. These findings expand the recommendation that patients with renal dysfunction should be considered as a high-risk group for cardiovascular disease and for ischemic stroke.