Inflammatory markers ‘not causal’ in post-stroke vascular events
MedWire News: Circulating inflammatory markers in stroke patients are associated not only with recurrent vascular events, but also with nonvascular causes of death, a prospective cohort study has found.
The researchers say their results suggest that inflammatory markers may not play a direct causal role in the etiology of vascular events after stroke, and call for further studies into the issue.
William Whiteley (Western General Hospital, Edinburgh, Scotland) and colleagues investigated the association of five blood markers - interleukin (IL)-6, glucose, C-reactive protein (CRP), fibrinogen, and white cell count - with recurrent vascular events after stroke.
They enrolled 817 patients with acute stroke and took blood samples on average 10 days after stroke onset. The cohort was followed-up for a mean of 2.12 years, during which time 106 patients had a first recurrent stroke, 34 had a myocardial infarction (MI), and 184 died (113 from vascular causes).
Writing in the journal Stroke, Whiteley's team reports that the unadjusted risks for stroke, MI, and vascular death increased with increasing tertiles of IL-6 and CRP. There was no such correlation with glucose, fibrinogen, or white cell count, however.
In adjusted analyses, the combined incidence of stroke, MI, and vascular death was significantly higher with higher levels of IL-6, CRP, and fibrinogen, with hazard ratios of 1.56, 1.08, and 1.45, respectively, for the 75th versus the 25th percentile ratio.
However, all five inflammatory markers were also significantly associated with an increased risk for death. Indeed, levels of IL-6, CRP, fibrinogen, and glucose were more strongly associated with death than with recurrent vascular events.
Most importantly, this was true for each individual cause of death - ie, vascular deaths and deaths attributable to the initial stroke as well as deaths attributable to other, nonvascular causes.
"These data suggest that CRP or IL-6 may not have a major causal role in recurrent vascular events after stroke," write Whiteley et al. "It is more likely that the observed association reflects an inflammatory response either to atherosclerosis or to its risk factors, or to an as yet unidentified trigger."
They conclude: "Future studies of the prediction of recurrent vascular events after stroke should concentrate on clinical variables or different blood markers."
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By Joanna Lyford