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An Analysis of Spatial Clustering of Stroke Types, In-hospital Mortality, and Reported Risk Factors in Alberta, Canada, Using Geographic Information Systems

  • Susan van Rheenen (a1), Timothy W.J. Watson (a2), Shelley Alexander (a3) and Michael D. Hill (a4)

Abstract

Background

Despite advances in the quality and delivery of stroke care, regional disparities in stroke incidence and outcome persist. Spatial analysis using geographic information systems (GIS) can assist in identifying high-risk populations and regional differences in efficacy of stroke care. The aim of this study was to identify and locate geographic clusters of high or low rates of stroke, risk factors, and in-hospital mortality across a provincial health care network in Alberta, Canada.

Methods

This study employed a spatial epidemiological approach using population-based hospital administrative data. Getis-Ord Gi* and Spatial Scan statistics were used to identify and locate statistically significant “hot” and “cold” spots of stroke occurrence by type, risk factors, and in-hospital mortality.

Results

Marked regional variations were found. East central Alberta was a significant hot spot for ischemic stroke (relative risk [RR] 1.43, p<0.001), transient ischemic attack (RR 2.25, p<0.05), and in-hospital mortality (RR 1.50, p<0.05). Hot spots of intracerebral hemorrhage (RR 1.80, p<0.05) and subarachnoid hemorrhage (RR 1.64, p<0.05) were identified in a major urban centre. Unexpectedly, stroke risk factor hot spots (RR 2.58, p<0.001) were not spatially associated (did not overlap) with hot spots of ischemic stroke, transient ischemic attack, or in-hospital mortality.

Conclusions

Integration of health care administrative data sets with geographic information systems contributes valuable information by identifying the existence and location of regional disparities in the spatial distribution of stroke occurrence and outcomes. Findings from this study raise important questions regarding why regional differences exist and how disparities might be mitigated.

Analyse de l’agrégation spatiale de types d’accident vasculaire cérébral, de mortalité hospitalière et de facteurs de risque rapportés en Alberta, au Canada, au moyen de la méthode GIS. Contexte: Malgré les progrès réalisés dans le domaine de la qualité et de la prestation des soins aux patients atteints d’un accident vasculaire cérébral (AVC), des inégalités régionales persistent quant à l’incidence de l’AVC et à son issue clinique. Une analyse spatiale au moyen de systèmes d’information géographique (GIS) peut aider à identifier des populations à haut risque et des différences régionales dans l’efficacité des soins prodigués aux patients atteints d’un AVC. Le but de cette étude était d’identifier et de localiser des agrégats géographiques de taux élevés ou bas d’AVC, de facteurs de risque et de mortalité hospitalière au sein d’un réseau provincial de soins de santé en Alberta, au Canada. Méthode: Nous avons utilisé une démarche épidémiologique spatiale appliquée à des données administratives hospitalières de la population. Les méthodes statistiques Getis-Ord Gi* et de scan spatial ont été utilisées pour identifier et localiser des points chauds et des points froids d’AVC par type, facteurs de risque et mortalité hospitalière. Résultats: Nous avons constaté qu’il existe des variations régionales importantes. La partie est de la région centrale de l’Alberta était un point chaud important en ce qui concerne l’AVC ischémique (risque relatif {RR} 1,43 ; p<0,001), l’ischémie cérébrale transitoire (RR 2,25 ; p<0,05) et la mortalité hospitalière (RR 1,50 ; p<0,05). Des points chauds d’hémorragie intracérébrale (RR 1,80 ; p<0,05) et d’hémorragie sous-arachnoïdienne (RR 1,64 <0,05) ont été identifiés dans un centre urbain important. À notre grande surprise, les points chauds pour les facteurs de risque de l’AVC (RR 2,58 ; p<0,001) n’étaient pas localisés aux mêmes endroits (ne coïncidaient pas) que les points chauds de l’AVC ischémique, de l’ischémie cérébrale transitoire ou de la mortalité hospitalière. Conclusions: L’intégration de données administratives de soins de santé à des systèmes d’information géographique fournit des informations précieuses en démontrant l’existence et en localisant des disparités régionales dans la distribution spatiale de la fréquence et de l’issue clinique de l’AVC. Nos constatations soulèvent d’importantes questions concernant les causes de ces différences régionales et comment elles pourraient être atténuées.

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Copyright

Corresponding author

Correspondence to: Susan van Rheenen, Faculty of Medicine, Department of Community Health Sciences, University of Calgary, TRW Building, 3rd Floor, 3280 Hospital Drive NW, Calgary, Alberta, Canada T2N 4Z6 Email: susan.vanrheenen@ucalgary.ca

References

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An Analysis of Spatial Clustering of Stroke Types, In-hospital Mortality, and Reported Risk Factors in Alberta, Canada, Using Geographic Information Systems

  • Susan van Rheenen (a1), Timothy W.J. Watson (a2), Shelley Alexander (a3) and Michael D. Hill (a4)

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