Is a reduced estimated glomerular filtration rate a risk factor for stroke in patients with type 2 diabetes?

Although chronic kidney disease is a risk factor for cardiovascular disease it is unclear whether diabetic patients with a reduced glomerular filtration rate (GFR), independent of ( micro) albuminuria, carry an increased risk of stroke. We therefore investigated the independent effect of estimated GFR (eGFR) on stroke events in patients with type 2 diabetes mellitus (T2DM). We studied T2DM patients with an eGFR >= 15 ml min(-1) per 1.73 m(2), who had no history of stroke. Patients were divided into four categories by the eGFR at baseline for comparison: >= 90, 60- 89, 30-59 and 15-29 ml min(-1) per 1.73 m(2). The end point was an incident stroke event. The Cox proportional hazard model was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). The study included a total of 1300 T2DM patients (546 women and 754 men) with a mean (+/- s.d.) age of 63 +/- 13 years. During a mean follow-up period of 3.7 +/- 1.4 years, 91 patients experienced an incident stroke event. Although a lower eGFR was associated with an increased stroke risk using a univariate model, statistical significance disappeared after adjusting for other risk factors including albuminuria. The HR ( 95% CI) was 0.75 (0.40-1.41, P = 0.373), 0.99 (0.50-1.95, P = 0.964) and 0.91 (0.36-2.28, P = 0.844) for patients with eGFRs of 60- 89, 30-59 and 15-29 ml min(-1) per 1.73m2, respectively, compared with patients with an eGFR >= 90. Clinical albuminuria remained a significant risk factor for stroke, and the adjusted HR compared with normoalbuminuria was 2.40 (1.46-3.95, P = 0.001). In conclusion, the association between reduced GFR and stroke events in patients with T2DM is likely to be mediated by albuminuria. Hypertension Research ( 2009) 32, 381-386; doi:10.1038/hr.2009.30; published online 27 March 2009