Chronic kidney disease (CKD) is independently associated with an increased risk of ischemic stroke and transient ischemic attack (TIA) in patients with pre-existing atherothrombotic disease, new findings suggest.
Common in patients with atherosclerotic vascular disease, CKD is linked to a high prevalence of traditional cardiovascular risk factors. Mild renal dysfunction has not been widely regarded as a risk factor for stroke, however. The new findings may change that view.
In the study, 6,685 patients (mean age 60 years) with documented coronary heart disease (CHD) and known serum creatinine levels were followed up for stroke or TIA for 4.8 to 8.1 years. None of the patients had a history of prior stroke or TIA.
Stroke was defined according to World Health Organization criteria, and appropriate clinical events resolving completely within 24 hours were diagnosed as TIA. CKD was defined as glomerular filtration rate (GFR) of 60 mL/min/1.73m2 or less according to the Cockroft-Gault
and Modification of Diet in Renal Disease (MDRD) equations.
About 25% of the study patients had CKD identified by both equations. Patients with CKD were more often female, older, leaner, less likely to smoke, more likely to have hypertension, and had higher mean HDL cholesterol and triglyceride levels than those without CKD.
The event rate of ischemic stroke or TIA was 6% in patients with CKD and 4% in patients without CKD. After adjusting for conventional risk factors and medication use, CKD determined by either equation was associated with a 1.5 times higher risk of stroke or TIA. The researchers found that the adjusted risk for ischemic stroke or TIA decreased as GFR increased.
The excess risk of events associated with CKD was not signif-icantly influenced by gender,
hypertension, diabetes, or treatment with lipid-modifying drugs, David Tanne, MD, and his colleagues at Tel-Aviv University in Israel, reported in Neurology (2006;67:224-228). Rates of ischemic stroke or TIA by serum creatinine level ranged from 3.5% for levels 0.90-1.09 mg/dL to 13.2% for levels higher than 1.70 mg/dL. Compared with patients with serum creatinine levels below 0.9 mg/dL, those with a serum creatinine level higher than 1.70 mg/dL had a threefold higher risk of events.
“Although some of the risk of CKD is due to its association with traditional vascular risk factors,
the presence of CKD, prevalent among patients with chronic CHD, remains an important independent prognostic marker for ischemic stroke risk,” the researchers wrote.