Risk factors among stroke subtypes and its impact on the clinical outcome of patients of Northern Portugal under previous aspirin therapy

Abstract

Background: In Western European countries, acute ischemic stroke (AIS) remains the third leading cause of death. Among the risk factors for cerebrovascular disease, some have more influence than others in certain stroke subtypes. The aim of this study was to evaluate the impact of risk factors among Stroke Subtypes on the clinical outcome of Portuguese patients under previous aspirin therapy.

Materials and methods: We studied a cohort of 371 patients diagnosed with AIS and a clinical follow-up protocol was set up.The patients were admitted in a Department of Internal Medicine of a major hospital. Standardized data assessment and stroke subtype classification (Oxfordshire Community Stroke Project) were used.

Results: Arterial hypertension (80.4 %), overweight (72.6 %) and dyslipidemia (62.0 %) were the most prevalent risk factors with no statistical differences among the group's subtypes. Current smoking was more prevalent in POCI(62.9 %) with differences among subtypes (p = 0.002). Atrial fibrillation was more commonly reported in TACI (39.3 %) and less common in POCI (8.1 %) (p < 0.001).Comparing TACI vs Non TACI Stroke Subtypes demonstrated major differences in cumulative survival,among the cases with no previous aspirin treatment, after 3 years (51.9 % vs 88.8 %).The increased risk of mortality at 12 months is consistently observed for the presence of a previous atrial fibrillation (OR 3.01 95 %CI 1.69-5.39), TACI subtype (OR 10.4 95 %CI 4.83-22.6) and NIHSS over 10 (OR 9.33 95 % CI 4,49-19.4). When we analyze the impact of previous aspirin treatment in the risk for a new stroke event, it seems to have a protective effect in a time frame of 12 months, but this protection is lost extending at 24 months (p = 0.094 vs p = 0.005).

Discussion: Our results indicate that smoking, atrial fibrillation and age have different relevance in their distribution among ischemic stroke subtypes at the time of diagnosis. Concerning the influence of the main stroke risk factors on the clinical outcome, our results present a strong influence of atrial fibrillation and of age. Severity of disease at diagnosis, represented by TACI subtype is clearly associated to decreased survival among patients with no record of previous aspirin therapy. Our results reinforce the relevance cohort studies of different populations, to achieve a more comprehensive knowledge of the impact of risk factors on stroke subtypes and on its clinical outcome.

Keywords: Ischemic stroke; Risk factors; Stroke outcome.