According to research published early online in the journal ‘Heart’, prior antiplatelet or anticoagulant use was associated with increased mortality following haemorrhagic stoke, but not ischaemic stroke.
The authors note that antiplatelets and anticoagulants are frequently prescribed for people at risk of stroke. There is good evidence for their use in secondary prevention following ischaemic stroke but their use in the primary prevention setting (especially antiplatelets) remains controversial. Aside from warfarin used for patients with atrial fibrillation, the effect of taking these agents prior to stroke on survival post-stroke is not well known.
In this study, researchers investigated the association between use of antiplatelets or anticoagulants prior to stroke and subsequent survival following stroke at various time points up to one year. Participants consisted of consecutive adult patients with stroke admitted to a large university hospital in the UK between Jan 2004 and Nov 2008 (n=3,308). The majority (86%) had an ischaemic stroke and the mean age of participants was 77 years. Information on prior use of antiplatelets and/or anticoagulants was obtained from the medication list of the patient on admission; around half (51%) were not taking any prior to their stroke.
The outcome of interest was mortality, measured in the short-term (7 and 30 days), medium-term (60 and 90 days) and long-term (one year), and ascertained using the hospital Patient Administrative System (PAS). Mortality risks were adjusted for age, gender, premorbid Rankin and stroke type. The main findings reported were as follows:
• One-year mortality was 35.2% for ischaemic stroke and 48.3% for haemorrhagic stroke.
• Compared with no previous therapy, use of antiplatelets or anticoagulants prior to ischaemic stroke was not associated with increased mortality at any of the time points studied.
• Use of antiplatelets or anticoagulants prior to haemorrhagic stroke was however associated with a worse prognosis at all time points.
• Use of warfarin was associated with a statistically significant risk of mortality post-haemorrhagic stroke at all time points evaluated, with the highest risk observed in the immediate post-stroke period (up to 60 days). All point estimates showed a grater than 2.3-fold increase in dying associated with prior warfarin use versus no therapy.
• A similar pattern was observed for aspirin at 30, 60 and 90 days post-stroke (no statistically significant association at other time points studied).
The authors say that this is the first study, to their knowledge, that has reported the effects of prior antiplatelet/anticoagulant treatment on mortality up to a year after hospital admission for stroke. A previous meta-analysis found antiplatelet use to be associated with an increased risk of mortality up to 90 days following haemorrhagic stroke; the current analysis shows that prior warfarin use is also associated with increased mortality in haemorrhagic stroke, up to one year of follow-up.
They go on to discuss some of the limitations of their study, for example they were unable to consider the management the patients received after admission, or the effect of the INR for those receiving anticoagulants (the higher mortality could have been attributable to cases with an INR above the therapeutic range). There was also no information on the dose, duration and indication for the use of antiplatelets/anticoagulants, and they were unable to explore cause-specific mortality.
The authors comment that further evaluation is required to determine whether post-stroke antiplatelet/anticoagulant choice has an impact on outcome (particularly for ischaemic stroke).