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Liver Disease (ALTs/Fatty Liver) a Possible Predictor of Stroke
 
 
  "Confirmatory data are needed regarding whether nonalcoholic fatty liver disease is an independent risk factor for ischemic stroke. If so, then measurement of alanine aminotransferase or aspartate aminotransferase-both of which are readily available and inexpensive-could be considered along with traditional stroke risk factors such as serum glucose, lipids, and blood pressure."
 
ScienceDaily (Jan. 10, 2011) - People suffering from fatty liver disease may be three times more likely to suffer a stroke than individuals without fatty liver, according to a study by researchers at St. Michael's Hospital and the London Health Sciences Centre. The study is the first to find a link between nonalcoholic fatty liver disease -- a disease characterized by the accumulation of fat in the liver in non drinkers -- and stroke.
 
In a research letter to the editor in the journal Epidemiology released January 6, Drs. Joel Ray, Ivan Ying and colleagues explain they found high levels of enzymes known to be markers of liver disease in adults who had an acute stroke. Between 2005 and 2009, they reviewed 103 consecutive adults who had an MRI-proven acute stroke between 2005 and 2009 and compared them to 200 adults with suspected acute stroke, but whose MRI was normal, thereby ruling out acute stroke.
 
"The risk of stroke in relation to fatty liver disease has never been tested," Dr. Ray says. "Our study shows a strong link between the two and the possibility in future that currently available blood liver enzyme tests, or novel markers of fatty liver, may be used to predict the risk of stroke and help us better care for and treat at risk patients."
 
Nonalcoholic fatty liver disease is a common condition that often has no symptoms or complications. Risk factors include obesity, high cholesterol, diabetes and, especially, insulin resistance.
 
While the findings are promising, additional research is needed to validate the study's findings, Dr. Ray said.
 
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Nonalcoholic Fatty Liver Disease and Acute Ischemic Stroke
 
Epidemiology:
January 2011 - Volume 22 - Issue 1 - pp 129-130
 
Ying, Ivan; Saposnik, Gustavo; Vermeulen, Marian J.; Leung, Andrew; Ray, Joel G. Department of Medicine, Schulich School of Medicine and Dentistry, London Health Sciences Center, University of Western Ontario, London, Ontario (Ying) Division of Neurology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, Ontario (Saposnik) Institute for Clinical Evaluative Sciences, University of Toronto, Toronto, Ontario (Vermeulen) Department of Medical Imaging, Schulich School of Medicine and Dentistry, London Health Sciences Centre, University of Western Ontario, London, Ontario (Leung) Departments of Medicine, Obstetrics and Gynecology, Health Policy Management and Evaluation, St. Michael's Hospital, University of Toronto, Toronto, Ontario, rayj@smh.toronto.on.ca (Ray)
 
To the Editor:
 
Nonalcoholic fatty liver disease is associated with a higher risk of self-reported cardiovascular disease.1 A recent systematic review also found persons with nonalcoholic fatty liver disease to have a 13% relative increase in carotid intima-media thickness.2 The risk of acute ischemic stroke in relation to inflammatory markers of nonalcoholic fatty liver disease remains unknown.
 
We conducted a cross-sectional records-based study at the London Health Sciences Centre in London, Ontario. We included adults aged 20 to 75 years with suspected acute stroke between January 2005 and December 2009; had all undergone diffusion-weighted magnetic resonance imaging (MRI), which is sensitive and specific for early changes of acute ischemic stroke. Persons with an acute ischemic stroke were considered cases, and those whose scan was negative served as controls. Study entry required that a patient have had serum alanine aminotransferase and aspartate aminotransferase concentrations measured within 90 days before, or within 72 hours after, the MRI. Patients with evidence of intracranial hemorrhage or malignancy on MRI were excluded.
 
The primary study outcome was biochemical evidence of inflammatory nonalcoholic fatty liver disease, defined as an elevated serum alanine aminotransferase concentration ≥95th percentile among the controls.
 
The study was done in accordance with a research protocol approved through the Research Ethics Boards of the London Health Sciences Centre.
 
We included 103 cases with, and 200 controls without, acute stroke, confirmed by diffusion-weighted imaging MRI. Details of participant characteristics are listed in the eAppendix ( http://links.lww.com/EDE/A443).
 
Transaminases were measured within a median of 2 days (cases) and 17 days (controls) of the diffusion-weighted imaging MRI. The adjusted odds ratio (OR) for acute stroke in the presence of an elevated alanine aminotransferase was 3.3 (95% confidence interval [CI] = 1.3-8.4) (Table). Similar elevations were observed for as partate aminotransferase concentration, as well as for alanine aminotransferase or aspartate aminotransferase in conjunction with an aspartate aminotransferase:alanine aminotransferase ratio under 2.0 (Table).
 
A study strength was the inclusion of both cases and controls who underwent sensitive diffusion-weighted MRI imaging for the assessment of acute stroke. This likely reduced the presence of diagnostic suspicion or referral bias,3 and correctly assigned persons with acute stroke as cases and those without acute stroke as controls. Second, we adjusted for a number of stroke risk factors, but not serum triglycerides or hepatic fat on imaging studies.1,4
 
Others have observed nonalcoholic fatty liver disease to predict the future risk of cardiovascular disease independent of metabolic syndrome.1,4 Among 1221 healthy Japanese men and women, the adjusted OR was 4.1 (95% CI = 1.6-11), but there were only 22 cardiovascular events, of which 12 were self-reported ischemic strokes.4 In a second study of 248 diabetic cases with cardiovascular disease, including just 29 nonfatal ischemic strokes, the associated OR between non alcoholic fatty liver disease and cardiovascular disease was 1.5 (95% CI =1.1-1.7).1 Our study, which focused exclusively on acute ischemic stroke, complements these findings.
 
Confirmatory data are needed regarding whether nonalcoholic fatty liver disease is an independent risk factor for ischemic stroke. If so, then measurement of alanine aminotransferase or aspartate aminotransferase-both of which are readily available and inexpensive-could be considered along with traditional stroke risk factors such as serum glucose, lipids, and blood pressure.
 
Ivan Ying
 
Department of Medicine
 
Schulich School of Medicine and Dentistry
 
London Health Sciences Center
 
University of Western Ontario
 
London, Ontario
 
Gustavo Saposnik
 
Division of Neurology
 
Department of Medicine
 
St. Michael's Hospital
 
University of Toronto
 
Toronto, Ontario
 
Marian J. Vermeulen
 
Institute for Clinical Evaluative Sciences
 
University of Toronto
 
Toronto, Ontario
 
Andrew Leung
 
Department of Medical Imaging
 
Schulich School of Medicine and Dentistry
 
London Health Sciences Centre
 
University of Western Ontario
 
London, Ontario
 
Joel G. Ray
 
Departments of Medicine, Obstetrics and Gynecology
 
Health Policy Management and Evaluation
 
St. Michael's Hospital
 
University of Toronto
 
Toronto, Ontario
 
rayj@smh.toronto.on.ca
 
REFERENCES
 
1. Targher G, Bertolini L, Poli F, et al. Nonalcoholic fatty liver disease and risk of future cardiovascular events among type 2 diabetic patients. Eur Rev Med Pharmacol Sci. 2005;9:269-271.
 
2. Sookian S, Pirola CJ. Non-alcoholic fatty liver disease is strongly associated with carotid atherosclerosis: a systematic review. J Hepatol. 2008;49:600-607.
 
3. Vandenbroucke JP, Cannegieter SC, Rosendaal FR. Travel and venous thrombosis: an exercise in thinking about bias. Ann Intern Med. 2009;151:212-213.
 
4. Hamaguchi M, Kojima T, Takeda N, et al. Nonalcoholic fatty liver disease is a novel predictor of cardiovascular disease. World J Gastroenterol. 2007;13:1579-1584.
 
 
 
 
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