학술논문
Outdoor air pollution, subtypes and severity of ischemic stroke - a small-area level ecological study
Document Type
Academic Journal
Source
International Journal of Health Geographics. June 17, 2014, Vol. 13
Subject
Language
English
ISSN
1476-072X
Abstract
Author(s): Ravi Maheswaran[sup.1] , Tim Pearson[sup.1] , Sean D Beevers[sup.2] , Michael J Campbell[sup.3] and Charles D Wolfe[sup.4] Background Stroke is a common cause of mortality and morbidity worldwide [1]. [...]
Background Evidence linking outdoor air pollution and incidence of ischemic stroke subtypes and severity is limited. We examined associations between outdoor PM.sub.10 and NO.sub.2 concentrations modeled at a fine spatial resolution and etiological and clinical ischemic stroke subtypes and severity of ischemic stroke. Methods We used a small-area level ecological study design and a stroke register set up to capture all incident cases of first ever stroke (1995-2007) occurring in a defined geographical area in South London (948 census output areas; population of 267839). Modeled PM.sub.10 and NO.sub.2 concentrations were available at a very fine spatial scale (20 meter by 20 meter grid point resolution) and were aggregated to output area level using postcode population weighted averages. Ischemic stroke was classified using the Oxford clinical classification, the Trial of Org 10172 in Acute Stroke Treatment (TOAST) etiological classification, National Institutes of Health Stroke Scale (NIHSS) score and a pragmatic clinical severity classification based on Glasgow coma score, ability to swallow, urinary continence and death Results Mean (SD) concentrations were 25.1 (1.2) ug/m.sup.3 (range 23.3-36.4) for PM.sub.10 and 41.4 (3.0) ug/m.sup.3 (range 35.4-68.0) for NO.sub.2. There were 2492 incident cases of ischemic stroke. We found no evidence of association between these pollutants and the incidence of ischemic stroke subtypes classified using the Oxford and TOAST classifications. We found no significant association with stroke severity using NIHSS severity categories. However, we found that outdoor concentrations of both PM.sub.10 and NO.sub.2 appeared to be associated with increased incidence of mild but not severe ischemic stroke, classified using the pragmatic clinical severity classification. For mild ischemic stroke, the rate ratio in the highest PM.sub.10 category by tertile was 1.20 (1.05-1.38) relative to the lowest category. The rate ratio in the highest NO.sub.2 category was 1.22 (1.06-1.40) relative to the lowest category. Conclusions We found no evidence of association between outdoor PM.sub.10 and NO.sub.2 concentrations and ischemic stroke subtypes but there was a suggestion that living in areas with elevated outdoor PM.sub.10 and NO.sub.2 concentrations might be associated with increased incidence of mild, but not severe, ischemic stroke. Keywords: Stroke, Air pollution, Environmental exposure, Subtypes, Severity
Background Evidence linking outdoor air pollution and incidence of ischemic stroke subtypes and severity is limited. We examined associations between outdoor PM.sub.10 and NO.sub.2 concentrations modeled at a fine spatial resolution and etiological and clinical ischemic stroke subtypes and severity of ischemic stroke. Methods We used a small-area level ecological study design and a stroke register set up to capture all incident cases of first ever stroke (1995-2007) occurring in a defined geographical area in South London (948 census output areas; population of 267839). Modeled PM.sub.10 and NO.sub.2 concentrations were available at a very fine spatial scale (20 meter by 20 meter grid point resolution) and were aggregated to output area level using postcode population weighted averages. Ischemic stroke was classified using the Oxford clinical classification, the Trial of Org 10172 in Acute Stroke Treatment (TOAST) etiological classification, National Institutes of Health Stroke Scale (NIHSS) score and a pragmatic clinical severity classification based on Glasgow coma score, ability to swallow, urinary continence and death Results Mean (SD) concentrations were 25.1 (1.2) ug/m.sup.3 (range 23.3-36.4) for PM.sub.10 and 41.4 (3.0) ug/m.sup.3 (range 35.4-68.0) for NO.sub.2. There were 2492 incident cases of ischemic stroke. We found no evidence of association between these pollutants and the incidence of ischemic stroke subtypes classified using the Oxford and TOAST classifications. We found no significant association with stroke severity using NIHSS severity categories. However, we found that outdoor concentrations of both PM.sub.10 and NO.sub.2 appeared to be associated with increased incidence of mild but not severe ischemic stroke, classified using the pragmatic clinical severity classification. For mild ischemic stroke, the rate ratio in the highest PM.sub.10 category by tertile was 1.20 (1.05-1.38) relative to the lowest category. The rate ratio in the highest NO.sub.2 category was 1.22 (1.06-1.40) relative to the lowest category. Conclusions We found no evidence of association between outdoor PM.sub.10 and NO.sub.2 concentrations and ischemic stroke subtypes but there was a suggestion that living in areas with elevated outdoor PM.sub.10 and NO.sub.2 concentrations might be associated with increased incidence of mild, but not severe, ischemic stroke. Keywords: Stroke, Air pollution, Environmental exposure, Subtypes, Severity