Silent brain infarction and rapid decline of kidney function in patients with CKD: a prospective cohort study

Several reports have found that chronic kidney disease (CKD) is an independent risk factor for stroke. However, little is known about whether cerebrovascular disease conversely predicts the outcome of kidney function. In view of the similarities between vascular beds of the kidney and brain, we hypothesized that silent brain infarction (SBI) could reflect the degree of injury in renal small vessels and predict the risk of progression of kidney disease.

Prospective cohort study.

142 patients with CKD (stages 3-5) admitted to our clinic for education about CKD from January 2006 to July 2007 were recruited and followed up for 2 years.

SBI.

Composite primary outcomes: doubling of serum creatinine level, development of end-stage renal disease defined as dialysis or transplant, and death from cardiovascular causes. Secondary outcome: rate of decrease in estimated glomerular filtration rate.

Brain magnetic resonance imaging was performed to determine the presence or absence of SBI.

At baseline, 87 patients had SBI. During follow-up, 43 patients (30.3%) developed the following primary outcomes: doubling of serum creatinine level (8 patients), dialysis therapy (32 patients), and death from cardiovascular causes (3 patients). In crude analysis, the presence of SBI predicted time to primary outcomes (P=0.01). A multivariate Cox model confirmed the presence of SBI to be an independent predictor of study outcomes (HR, 2.16; 95% CI, 1.01-4.64; P=0.04). Estimated glomerular filtration rate decreased more in patients with SBI than in those without SBI (-0.11/y vs -0.06/y relative to baseline value; P=0.005).

Study size was small.

We showed that SBI was an important independent prognostic factor for the progression of kidney disease in patients with CKD. Our findings suggest that patients with SBI should be considered a high-risk population for decreased kidney function.