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Hepatitis C May Increase Risk of Strokes

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Hepatitis C virus (HCV) infection significantly increases the likelihood of having a stroke, but further information is needed to understand underlying mechanisms and identify related risk factors such as HCV genotype, according to a meta-analysis described in the November 12, 2013, edition of PLoS ONE.

Chronic hepatitis C is associated with several conditions not directly related to the liver, including cardiovascular disease. He Huang from the Chinese Academy of Medical Sciences and colleagues performed a meta-analysis to examine whether HCV infection increases stroke risk relative to the population without hepatitis C.

Several epidemiological studies have analyzed the association between hepatitis C and stroke or cerebrovascular death, but findings have been inconsistent, the authors noted as background.

Two independent investigators identified eligible studies through structured keyword searches of several databases including Embase, Medline, the Cochrane Library, and Google Scholar. They considered all English-language epidemiological studies published through August 2013 that provided either an estimate of stroke risk among people with hepatitis C compared to an uninfected population, or an estimate of risk of HCV infection among people who had and did not have strokes. Mathematical models were used to synthesize the data.

After initial review of more than 300 abstracts, 9 potentially relevant studies were identified and full-text was retrieved for detailed evaluation. Of these, 3 were excluded due to inadequate data, leaving 6 studies included in a qualitative analysis (5 of them retrospective) and 4 in the quantitative meta-analysis. Together the meta-analysis included more than 22,000 people with hepatitis C and more than 87,000 infected control subjects.

Results

  • In a pooled multifactor analysis, the adjusted odds ratio was 1.58, or a 58% higher risk of stroke in the group with hepatitis C.
  • After omitting 1 study with widely varying results, the pooled adjusted odds ratio was 1.97, or nearly double the risk.

"This meta-analysis suggested that HCV infection increased the risk of stroke," the study authors summarized. "More prospective cohort studies will be needed to confirm this association with underlying biological mechanisms in the future."

"The mechanism(s) by which HCV may favor stroke is not known," they explained in their discussion. "Increasing evidence has showed that chronic HCV infection increased the risk of ultrasonographically defined carotid intima-media thickness and or plaque, which are predictors of cerebrovascular disease. It is well-known that chronic inflammation plays an important role in the instability of plaque." Hepatitis C is also associated with increased risk of metabolic abnormalities such as type 2 diabetes.

"[F]uture studies may evaluate the impacts of different genotypes of HCV infection on stroke," they concluded. "The updating of this meta-analysis will give us more information and may help inform clinical practice guidelines in the future."

2/7/14

Reference

H Huang, R Kang, Z Zhao, et al. Hepatitis C virus infection and risk of stroke: a systematic review and meta-analysis. PLoS ONE 8(11):e81305. November 12, 2013.