Biomedical subjects
Nerses Sanossian
Publications and source records attributed to Nerses Sanossian.
Frequency and determinants of nonpublication of research in the stroke literature.
BACKGROUND AND PURPOSE: Selective nonpublication will yield publication bias and a published literature imperfectly representative of the full range of scientific findings. We evaluated the proportion of research abstracts presented at the leading United States research meeting in stroke, the International Stroke Conference (ISC), which were subsequently published as full-length articles and investigated the factors associated with full manuscript publication. METHODS: Features of all abstracts presented at the annual ISC meeting in February 2000 were analyzed. Search of the National Library of Medicine PubMed database and written communication with abstract authors was performed to determine conversion of abstracts to fully published manuscripts over the subsequent 5 years. RESULTS: Among the 353 abstracts presented at the 2000 International Stroke Conference, 108 were oral presentations and 245 posters. Overall, 202/353 (62.3%) resulted in full-length publications, with a median time to publication of 15 months. In multivariate analysis, factors increasing likelihood of full-length publication were: platform rather than poster presentations (odds ratio [OR] 3.0, 95% CI, 1.6 to 5.5), authors with a university affiliation (OR 2.2, 95% CI, 1.2 to 4.1), and European region of origin (OR 2.2, 95% CI, 1.1 to 4.4), whereas topic concerning community/risk factors decreased the likelihood of publication (OR 0.3, 95% CI, 0.16 to 0.74). Positive results, multicenter collaboration and industry sponsorship did not affect publication rate. CONCLUSIONS: Approximately 1 of every 3 abstracts presented at an international stroke meeting was not published as a full manuscript within 5 years. Poster abstracts were less likely to be published in full manuscript form than oral presentations.
Predictors of cerebral microbleeds in acute ischemic stroke and TIA patients.
BACKGROUND: Cerebral microbleeds (CMB) detected on gradient-echo T2*-weighted MRI have been associated with cognitive impairment and the potential for increased risk of intracranial hemorrhage. We evaluated risk factors for these microangiopathic lesions in a cohort of stroke and transient ischemic attack patients. METHODS: Presence and number of CMB in consecutive acute stroke patients admitted to a university hospital stroke service over an 18-month period were rated. Multivariate models were generated to determine the contribution of 21 demographic and clinical variables to the frequency and number of CMB. RESULTS: Of 164 patients (mean age 71 years, 52% female), 57 (35%) had CMB evident on gradient-echo T2*-weighted MRI. CMB were more commonly noted among patients with small vessel disease ischemic stroke mechanism (47%) than large vessel atherothromboembolic (12%) or cardioembolic (18%, p = 0.0001). In univariate analysis, patients with CMB were older, (p = 0.008), more likely to have been on >1 antihypertensive prior to admission (p = 0.024) than those without CMB. In multivariate logistic regression analyses, presumed small vessel stroke subtype, history of atrial fibrillation, being on >1 antihypertensive prior to admission, and smoking were independent factors increasing the risk of CMB. Logistic regression analysis by number of CMB showed almost similar findings. CONCLUSIONS: CMB are more frequently noted in hospitalized stroke and transient ischemic attack patients with small vessel ischemia, as well as those with important modifiable vascular risk factors like atrial fibrillation and smoking.
Analysis of thrombi retrieved from cerebral arteries of patients with acute ischemic stroke.
BACKGROUND AND PURPOSE: Information regarding the histological structure of thromboemboli that cause acute stroke provides insight into pathogenesis and clinical management. METHODS: This report describes the histological analysis of thromboemboli retrieved by endovascular mechanical extraction from the middle cerebral artery (MCA) and intracranial carotid artery (ICA) of 25 patients with acute ischemic stroke. RESULTS: The large majority (75%) of thromboemboli shared architectural features of random fibrin:platelet deposits interspersed with linear collections of nucleated cells (monocytes and neutrophils) and confined erythrocyte-rich regions. This histology was prevalent with both cardioembolic and atherosclerotic sources of embolism. "Red" clots composed uniquely of erythrocytes were uncommon and observed only with incomplete extractions, and cholesterol crystals were notably absent. The histology of thromboemboli that could not be retrieved from 29 concurrent patients may be different. No thrombus >3 mm wide caused stroke limited to the MCA, and no thrombus >5 mm wide was removed from the ICA. A mycotic embolus was successfully removed in 1 case, and a small atheroma and attached intima were removed without clinical consequence from another. CONCLUSIONS: Thromboemboli retrieved from the MCA or intracranial ICA of patients with acute ischemic stroke have similar histological components, whether derived from cardiac or arterial sources. Embolus size determines ultimate destination, those >5 mm wide likely bypassing the cerebral vessels entirely. The fibrin:platelet pattern that dominates thromboembolic structure provides a foundation for both antiplatelet and anticoagulant treatment strategies in stroke prevention.
Achieving target cholesterol goals after stroke: is in-hospital statin initiation the key?
BACKGROUND: National advisories recommend statin therapy as an element of secondary prevention for patients with ischemic stroke or transient ischemic attack of atherosclerotic origin. Statins are of proven benefit in persons at high risk of vascular disease. OBJECTIVES: To evaluate the effects of in-hospital initiation of statins on 3-month treatment adherence rates and achievement of national guideline target cholesterol goals. METHODS: Data were collected in consecutively encountered patients with ischemic stroke or transient ischemic attack admitted to a university hospital stroke service beginning September 1, 2002. Patients were included in the study if they were not receiving a statin before admission and had an indication for statin therapy. Adherence to statin treatment and achievement of national guideline target cholesterol goals were assessed 3 months after discharge. RESULTS: From September 1, 2002, through April 30, 2005, 92 (17%) of 552 individuals met the study criteria. Hospital initiation of statin therapy yielded high rates of adherence (93% [86/92]), lowered mean low-density lipoprotein cholesterol levels from 120 to 78 mg/dL (3.1 to 2.0 mmol/L; P<.001), and increased the proportion of patients with low-density lipoprotein cholesterol levels lower than 100 mg/dL (2.6 mmol/L) from 36% to 88% (P<.001) at 3 months. CONCLUSIONS: Statin initiation during hospitalization for an ischemic cerebrovascular event is associated with high rates of adherence to treatment, lowering of low-density lipoprotein cholesterol levels, and higher rates of achieving national cholesterol guidelines.
Multimodality stroke prevention.
BACKGROUND: Prevention harbors the greatest potential for reducing the societal burden from stroke. As evidence accumulates on the multifactorial pathogenesis of vascular disease and the impact of novel combination therapies targeted at reducing recurrent vascular events, a new paradigm is emerging, which is that of multimodality vascular prevention. Knowledge of the evidence behind this strategy and the effective means for implementing it could be useful to the practicing neurologist taking care of stroke patients. REVIEW SUMMARY: Our review presents the evidence behind the broadening therapeutic options for recurrent vascular event prevention in ischemic stroke patients whose underlying stroke pathophysiologic mechanism is either presumed to be due to atherosclerosis or who have prior evidence of systemic atherosclerosis. We elaborate on conventional and novel vascular risk factors, as well as risk factor prediction models. Therapies discussed include antithrombotics, statins, antihypertensives, surgical/endovascular treatments, and lifestyle modification. Basis for evidence (or the lack thereof), national guideline recommendations, areas of controversy, and avenues of future focus for these treatments are also discussed in this paper. Furthermore, the knowledge-treatment gap as it pertains to optimal vascular risk-factor control and appropriate initiation and maintenance of evidence-based preventive therapies is explored, and an effective hospital-based intervention involving the in-hospital initiation of these treatments prior to discharge, that may help bridge this gap, is detailed. CONCLUSIONS: Neurologists should be aware that a timely, systematic, evidence-based multimodal preventive approach to atherothrombotic disease in stroke patients that transcends the continuum of care across points of service will likely increase treatment rates and improve clinical outcomes.
Chronic diarrhea associated with vagal nerve stimulation.
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