Anemia and Chronic Kidney Disease are Potential Risk Factors for Mortality in Stroke Patients: A Historic Cohort Study

Patrizia Del Fabbro; Jean-Christophe Luthi; Emmanuel Carrera; Patrik Michel; Michel Burnier; Bernard Burnand

Disclosures

BMC Nephrology. 2010;11(27) 

In This Article

Abstract and Introduction

Abstract

Background: Chronic kidney disease (CKD) is associated to a higher stroke risk. Anemia is a common consequence of CKD, and is also a possible risk factor for cerebrovascular diseases. The purpose of this study was to examine if anemia and CKD are independent risk factors for mortality after stroke.
Methods: This historic cohort study was based on a stroke registry and included patients treated for a first clinical stroke in the stroke unit of one academic hospital over a three-year period. Mortality predictors comprised demographic characteristics, CKD, glomerular filtration rate (GFR), anemia and other stroke risk factors. GFR was estimated by means of the simplified Modification of Diet in Renal Disease formula. Renal function was assessed according to the Kidney Disease Outcomes Quality Initiative (K/DOQI)-CKD classification in five groups. A value of hemoglobin < 120 g/L in women and < 130 g/L in men on admission defined anemia. Kaplan-Meier survival curves and Cox models were used to describe and analyze one-year survival.
Results: Among 890 adult stroke patients, the mean (Standard Deviation) calculated GFR was 64.3 (17.8) ml/min/1.73 m2 and 17% had anemia. Eighty-two (10%) patients died during the first year after discharge. Among those, 50 (61%) had K/DOQI CKD stages 3 to 5 and 32 (39%) stages 1 or 2 (p < 0.001). Anemia was associated with an increased risk of death one year after discharge (p < 0.001). After adjustment for other factors, a higher hemoglobin level was independently associated with decreased mortality one year after discharge [hazard ratio (95% CI) 0.98 (0.97–1.00)].
Conclusions: Both CKD and anemia are frequent among stroke patients and are potential risk factors for decreased one-year survival. The inclusion of patients with a first-ever clinical stroke only and the determination of anemia based on one single measure, on admission, constitute limitations to the external validity. We should investigate if an early detection and management of both CKD and anemia could improve survival in stroke patients.

Introduction

Stroke is an increasing cause of mortality and severe neurological disability, including late-life dementia, worldwide.[1–3] Chronic kidney disease (CKD) is an independent risk factor for cerebrovascular diseases.[4,5] Anemia, a frequent feature of reduced kidney function, could actually play a role in the relationship between CKD and stroke.[6] However, the relationship between CKD-, anemia- and stroke-related outcomes needs to be studied further. Chronic kidney disease (CKD) is also an increasing public health problem worldwide, associated with poor outcomes and high cost.[7] A loss of renal function is associated with an elevated risk of stroke and cardiovascular diseases compared to the general population.[8–10] Other risk factors for stroke are commonly encountered in dialysis patients.[11]

Friedman found out that serum creatinine is a strong and independent predictor of survival after a stroke,[12] while another study indicated that this association was related to the presence of anemia.[6] When anemia was present with chronic kidney disease, the risk of stroke increased clearly compared to patients with CKD without anemia, in which the risk of stroke was only moderately increased. Among those patients with anemia and low creatinine clearance the crude stroke rate per 1000 person-years was 10.53 and, among those without anemia and low creatinine clearance, the rate was 2.85.[6] To further study the role of CKD and anemia on outcome in stroke patients, the objective of this study was to examine the association between chronic kidney disease and anemia with in-hospital mortality and one-year survival among hospitalized stroke patients.

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