Impact of Prestroke Oral Anticoagulation on Severity and Outcome of Ischemic and Hemorrhagic Stroke in Patients with Atrial Fibrillation

Abstract

Background: Stroke prevention with oral anticoagulation is effective in patients with atrial fibrillation. An additional beneficial effect of oral anticoagulation prior to the event on stroke severity and prognosis was suggested in ischemic strokes. We tested whether this benefit is preserved after inclusion of hemorrhagic strokes and adjustment for prestroke living conditions. Methods: Data were used from a prospective hospital-based intervention trial evaluating quality of care and outcome in ten district hospitals. All ischemic and hemorrhagic stroke patients with atrial fibrillation were included. We analyzed separate multivariable regression models to identify factors associated with prescription of oral anticoagulation before stroke and to investigate the independent effect of anticoagulation on admission stroke severity, 3-month mortality and functional outcome. Results: The analysis comprised 804 (718 ischemic, 86 hemorrhagic) stroke patients admitted between July 2003 and March 2005. Males, patients aged 65–84, living independently, with diabetes, previous cerebrovascular event or additional high cardioembolic risks were more likely to receive oral anticoagulation before admission. Admission international normalized ratio (INR) between 2 and 3 (OR 0.35, 95% CI: 0.17–0.71) or higher (OR 0.32, 95% CI: 0.11–0.92) was associated with less severe strokes (including hemorrhagic strokes) compared with INR <2. Anticoagulation was associated with decreased risk of death and poor functional outcome (modified Rankin Scale >3) at 3 months (OR 0.54, 95% CI: 0.36–0.84, and OR 0.70, 95% CI: 0.47–1.06). After adjustment for stroke severity, anticoagulation had no additional effect on mortality and functional outcome. Conclusions: The beneficial effect of prestroke anticoagulation on stroke outcome related to the reduced stroke severity is not offset by adverse effects in hemorrhagic stokes.

Preadmission Oral Anticoagulant Treatment and Clinical Outcome Among Patients Hospitalized With Acute Stroke and Atrial Fibrillation

“…Our findings among patients with ischemic stroke are in line with several smaller existing studies, which have also reported preadmission OAT to be associated with lower ischemic stroke severity 7,10-13 and lower mortality risk, in particular, among patients with an INR>2.00. 7,11,12 We also found that the lower mortality among OAT users seemed to be mediated by the lower stroke severity, which is in accordance with previous findings. Overall and subgroup analysis according to preadmission intensity of oral anticoagulation treatment (OAT).…”

“…The low use of OAT in our study population is comparable with previous reports on patients with AF admitted with stroke [7][8][9][10][11][12][13] and patients with AF in general. 14 Improvements over time have been observed, as is also the case in our study, across geographical settings and healthcare systems, which may reflect the effect of national and international promotion of guidelines recommendations; however, still a high proportion of eligible patients with AF remains insufficiently treated, in particular, when the intensity of the OAT is also taken into account.…”

“…The outcome of patients with ICH receiving OAT is, therefore, of major importance when examining the overall effect of OAT on stroke outcomes on a population level. However, to date, only the study by Audebert et al 11 seems to have tried to account for the potentially adverse prognostic effect of preadmission OAT on patients with ICH (patients with ICH were also included in the study by Haeusler et al 13 but seem not to have been included in the analyses on clinical outcome). Audebert et al 11 included 86 patients with ICH in a study based on data from 2 academic and 12 community hospitals in Germany participating in a nonrandomized, community intervention study.…”

“…Only a few observational studies have examined the association, and overall preadmission OAT has been found to be associated with less severe stroke, lower case fatality, and improved functional level. [7][8][9][10][11][12][13] If this association is truly causal, it constitutes a strong argument for increasing the efforts to ensure that eligible patients with AF receive OAT according to clinical guideline recommendations. This is important because several studies have found that high proportions of eligible patients with AF, including high-risk patients, are withheld OAT.…”

“…Furthermore, the ability to control adequately for possible confounding factors and the statistical precision could be questioned. Finally, all except for one small study 11 have been restricted to patients with ischemic stroke although the possible beneficial effect of OAT on ischemic events could potentially be outweighed by a potential harm in patients with intracerebral hemorrhage (ICH). There is consequently a need for additional large-scale population-based studies.…”