Age dependent impact of estimated glomerular filtration rate on long-term survival after ischaemic stroke

Neurological complications in chronic kidney disease patients

Chronic kidney disease (CKD) is associated with a high prevalence of cerebrovascular disorders such as stroke, white matter diseases, intracerebral microbleeds and cognitive impairment. This situation has been observed not only in end-stage renal disease patients but also in patients with mild or moderate CKD. The occurrence of cerebrovascular disorders may be linked to the presence of traditional and non-traditional cardiovascular risk factors in CKD. Here, we review current knowledge on the epidemiological aspects of CKD-associated neurological and cognitive disorders and discuss putative causes and potential treatment. CKD is associated with traditional (hypertension, hypercholesterolaemia, diabetes etc.) and non-traditional cardiovascular risk factors such as elevated levels of oxidative stress, chronic inflammation, endothelial dysfunction, vascular calcification, anaemia and uraemic toxins. Clinical and animal studies indicate that these factors may modify the incidence and/or outcomes of stroke and are associated with white matter diseases and cognitive impairment. However, direct evidence in CKD patients is still lacking. A better understanding of the factors responsible for the elevated prevalence of cerebrovascular diseases in CKD patients may facilitate the development of novel treatments. Very few clinical trials have actually been performed in CKD patients, and the impact of certain treatments is subject to debate. Treatments that lower LDL cholesterol or blood pressure may reduce the incidence of cerebrovascular diseases in CKD patients, whereas treatment with erythropoiesis-stimulating agents may be associated with an increased risk of stroke but a decreased risk of cognitive disorders. The impact of therapeutic approaches that reduce levels of uraemic toxins has yet to be evaluated.

Urea

Urea is generated by the urea cycle enzymes, which are mainly in the liver but are also ubiquitously expressed at low levels in other tissues. The metabolic process is altered in several conditions such as by diets, hormones, and diseases. Urea is then eliminated through fluids, especially urine. Blood urea nitrogen (BUN) has been utilized to evaluate renal function for decades. New roles for urea in the urinary system, circulation system, respiratory system, digestive system, nervous system, etc., were reported lately, which suggests clinical significance of urea.

Renal Dysfunction in Stroke Patients: A Hospital-Based Cohort Study and Systematic Review

Background and purpose

Renal dysfunction (i.e. a reduced estimated glomerular filtration rate, eGFR) is commonly found in hospitalized stroke patients but its associations with Patients' characteristics and outcome require further investigation.

Methods

We linked clinical data from stroke patients enrolled between 2005 and 2008 into two prospective hospital registers with routine laboratory eGFR data. The eGFR was calculated using the Modification of Diet in Renal Disease method and renal dysfunction was defined as <60 ml/min/1·73 m2. In addition we systematically reviewed studies investigating the association between eGFR and outcome after stroke.

Results

Of 2520 patients who had an eGFR measured on admission hospital, 805 (32%) had renal dysfunction. On multivariate analysis, renal dysfunction was significantly less likely in those with a predicted good outcome (OR 0·27, 95% CI 0·21, 0·36) based on the well-validated six simple variable model. After adjustment for other predictive factors, stroke patients with renal dysfunction were more likely to die in hospital compared with those without (odds ratio 1·59, 95% confidence intervals 1·26, 2·00). Of the 31 studies involving 41 896 participants included in the systematic review, 18 studies found that low eGFR was an independent predictor of death and 6 reported a significant association with death and disability.

Conclusion

Our findings suggest that renal dysfunction on admission is common and associated with poor outcomes over the first year. Further work is required to establish to what extent these associations are causal and whether treating impaired renal function improves outcomes.

Effects of low estimated glomerular filtration rate on outcomes after stroke: a hospital-based stroke registry in China

BACKGROUND AND PURPOSE

As uncertainty persists over the prognostic significance of low estimated glomerular filtration rate (eGFR) in acute stroke, the effects of low eGFR on death/disability amongst participants with acute stroke in China were determined.

METHODS

Nanjing First Hospital stroke registry was a prospective cohort study of stroke patients. Patients with acute stroke (brain infarction, intracerebral hemorrhage or subarachnoid hemorrhage) within 7 days of onset were recruited consecutively from 2004 to 2008. Baseline eGFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation. Outcomes were death/disability, defined by scores 3-6 on the modified Rankin Scale at 90 days.

RESULTS

A total of 1909 participants were included in the present analyses. Of them, 112 (5.9%) had baseline moderate to severe decrease in eGFR (G3b-4) and increasing risk of higher National Institutes of Health Stroke Scale (NIHSS) scores. Low eGFR was associated with increasing risk of death/disability at 90 days [G3b-4, odds ratio 2.58 (95% confidence interval 1.71-3.91); G3a, 1.86 (1.35-2.56); G2, 1.21 (0.96-1.52); P trend <0.001). However, the association was not statistically significant after adjustment for demographic and clinical factors including NIHSS scores.

CONCLUSIONS

There were no appreciable effects of low eGFR on death/disability at 90 days independent of other prognostic factors in Chinese patients with acute stroke.