Abstract 3092: Does Pre-existing Antiplatelet Treatment Influence Post-thrombolysis Intracranial Hemorrhage In Community Treated Ischemic Stroke Patients?

Abstract

Background: Post-thrombolysis ICH is associated with poor outcomes. Previous investigations have attempted to determine the relationship between pre-existing anti-platelet (AP) use and the safety of intravenous thrombolysis, but have been limited by low event rates thus decreasing the precision of estimates. Our objective was to determine whether pre-existing AP therapy increases the risk of ICH following thrombolysis. Methods: Consecutive cases of ED treated thrombolysis patients were identified using multiple methods, including active and passive surveillance. Retrospective data were collected from 4 hospitals from 1996-2005, and 24 distinct hospitals from 2007-2010 as part of a cluster randomized trial. The same chart abstraction tool was used during both time periods and data was subjected to numerous quality control checks. Hemorrhages were classified using a pre-specified methodology: ICH was defined as presence of hemorrhage in radiographic interpretations of follow up imaging (primary outcome). Symptomatic ICH (secondary outcome) was defined as radiographic ICH with associated clinical worsening. A multivariable logistic regression model was constructed to adjust for clinical factors previously identified to be related to post-thrombolysis ICH. The models included: pre-existing AP use, age*, NIHSS*, pre-treatment systolic blood pressure, onset to treatment interval, pre-treatment blood glucose*, tobacco use, presence of post-treatment protocol violations (*variable classified by quartile). As there were fewer SICH events, the multivariable model was constructed similarly, except that variables divided into quartiles in the primary analysis were dichotomized at the median. Results: There were 830 patients included, with 47% having documented pre-existing AP treatment. The mean age was 69 years, the cohort was 53% male, and the median NIHSS was 12. The unadjusted proportion of patients with any ICH was 15.1% without AP and 19.3% with AP (difference 4.2% [95% CI: -1.2% - 9.6%]); for SICH this was 6.1% without AP and 9% with AP (difference 3.1% [95%CI: -1-6.7%]). No significant association between pre-existing AP treatment with radiographic or symptomatic ICH was observed ( table ). Conclusions: We did not find that AP treatment was associated with post-thrombolysis ICH or SICH in this cohort of community treated patients. Pre-existing tobacco use, younger age, and lower severity were associated with lower odds of SICH. An association between AP therapy and SICH may still exist - further research with larger sample sizes is warranted in order to detect smaller effect sizes.