Linares, Guillermo

BACKGROUND: Small, randomized trials of patients with cervical artery dissection showed conflicting results regarding optimal stroke prevention strategies. We aimed to compare outcomes in patients with cervical artery dissection treated with antiplatelets versus anticoagulation. METHODS: This is a multicenter observational retrospective international study (16 countries, 63 sites) that included patients with cervical artery dissection without major trauma. The exposure was antithrombotic treatment type (anticoagulation versus antiplatelets), and outcomes were subsequent ischemic stroke and major hemorrhage (intracranial or extracranial hemorrhage). We used adjusted Cox regression with inverse probability of treatment weighting to determine associations between anticoagulation and study outcomes within 30 and 180 days. The main analysis used an as-treated crossover approach and only included outcomes occurring with the above treatments. RESULTS: The study included 3636 patients (402 [11.1%] received exclusively anticoagulation and 2453 [67.5%] received exclusively antiplatelets). By day 180, there were 162 new ischemic strokes (4.4%) and 28 major hemorrhages (0.8%); 87.0% of ischemic strokes occurred by day 30. In adjusted Cox regression with inverse probability of treatment weighting, compared with antiplatelet therapy, anticoagulation was associated with a nonsignificantly lower risk of subsequent ischemic stroke by day 30 (adjusted hazard ratio [HR], 0.71 [95% CI, 0.45–1.12]; P =0.145) and by day 180 (adjusted HR, 0.80 [95% CI, 0.28–2.24]; P =0.670). Anticoagulation therapy was not associated with a higher risk of major hemorrhage by day 30 (adjusted HR, 1.39 [95% CI, 0.35–5.45]; P =0.637) but was by day 180 (adjusted HR, 5.56 [95% CI, 1.53–20.13]; P =0.009). In interaction analyses, patients with occlusive dissection had significantly lower ischemic stroke risk with anticoagulation (adjusted HR, 0.40 [95% CI, 0.18–0.88]; P interaction =0.009). CONCLUSIONS: Our study does not rule out the benefit of anticoagulation in reducing ischemic stroke risk, particularly in patients with occlusive dissection. If anticoagulation is chosen, it seems reasonable to switch to antiplatelet therapy before 180 days to lower the risk of major bleeding. Large prospective studies are needed to validate our findings.

Introduction: Four randomized clinical trials have not demonstrated the superiority of anticoagulation over antiplatelet therapy in the prevention of recurrent embolic stroke of undetermined source (ESUS). In this multicenter observational cohort study, we evaluated long-term outcomes associated with various antithrombotic strategies according to potential embolic sources. Methods: A multicenter retrospective observational cohort of consecutive adult patients with ESUS was queried (n=27 sites). Comparisons were made between patients treated with single or combination antiplatelet therapy versus anticoagulation (direct oral anticoagulant, vitamin K antagonist, low molecular weight heparin) with or without antiplatelet therapy initiated within 7 days of stroke. The primary composite outcome of recurrent stroke, major bleeding, or death was assessed using unadjusted and adjusted Cox proportional hazards regression, with clustering by site. Causal inference was assessed using inverse probability of treatment weighted regression adjustment (IPTWRA), accounting for propensity for antiplatelet treatment, with effect estimates summarized as the average treatment effect (ATE) over time (in days). Adjusted models accounted for age, stroke severity, vascular risk factors, and major categories of potential embolic sources. Results: Of the 2201 included patients (n=218 treated with anticoagulation) followed over a median of 564 days (interquartile range [IQR] 154-1124), the median age was 65y (IQR 54-74) and 49.8% were female. Patients treated with anticoagulation were older with more frequent previous stroke, concomitant left ventricular dysfunction, and more severe deficits. Over 4541 person-years of follow-up, the annualized incidence rate of the primary outcome was 14.6% (95% confidence interval [CI], 13.6%-15.8%). Compared to anticoagulation, antiplatelet(s) use was not associated with a lower risk of the primary outcome in the adjusted Cox model (HR 0.91, 95% CI, 0.64-1.29) or in the IPTWRA model (average treatment effect 0.14, 95% CI, -1376.6 to 1376.9). Major bleeding events trended toward significance in the adjusted Cox model (HR 0.51, 95% CI 0.25-1.04) but were no different with IPTWRA (ATE 58.9, 95% CI, -125.4 to 243.2). Conclusions: These results validate the observations of randomized trials indicating a lack of benefit of anticoagulation over antiplatelet therapy in ESUS. A more detailed analysis of heterogeneity of treatment effect is under way.

Background: It is known that there are discrepancies between insurance status and access to care for a variety of health conditions. In addition, differences have been shown in initial in-hospital management of stroke as well as outcomes in the acute setting. We sought to examine the relationship between insurance status and risk of recurrent stroke, major bleeding or death following an incident cryptogenic stroke. Methods: Patients with cryptogenic stroke included in a multicenter (n=27 sites) retrospective observational cohort and complete insurance status were evaluated for a primary composite outcome of recurrent stroke, major bleeding, or death. Insurance providers were categorized by Private/Veterans Administration, Medicare, Other, and Medicaid/pending/None, with the primary carrier ranked in that order when multiple insurance carriers applied. Descriptive statistics and an adjusted Cox proportional hazards regression were used to associate the primary insurance provider with the composite outcome, and with each unique secondary outcome, adjusting for age, stroke severity, pre-stroke disability, atherosclerotic risk factors, and potential embolic sources (e.g., patent foramen ovale). Results: Of the 2201 patients, 2006 (91.1%) had reported insurance information and were followed for a median of 1.50 years (interquartile range [IQR 0.41 - 2.99y]). The majority of patients were primary Medicare beneficiaries (42.3%), followed by private insurance (36.7%), Medicaid/none (18.1%) and Other (2.9%). Although there were important differences in demographic and neurodiagnostic results across insurance groups, compared to Private/VA beneficiaries, beneficiaries for Medicaid/pending/none had a higher rate of the composite outcome in adjusted regression (adjusted hazard ratio [HR] 1.35, 95% confidence interval [CI], 1.07-1.69) which was driven largely by the higher rate of recurrent stroke (adjusted HR 1.33, 95%CI, 1.02-1.73) with no significant difference in rate of major bleeding or death (p>0.05 for both). Conclusions: Independent of age, race, pre-existing disability, and atherosclerotic risk factors, insurance status was independently predictive of recurrent stroke in this diverse cohort of cryptogenic stroke.