A preliminary spatial analysis of diagnosed stroke disease in Osun state, Nigeria

Introduction There have been a number of clinical studies on diagnosed Stroke disease. However, there have been few studies on the geographical disparities for stroke. This study investigates the spatial pattern of stroke disease reflecting socio-demographic characteristics in the State. Methods Stroke patients' admissions for 22 years (from 1990 to 2012) were examined. Their socio-demographic characteristics were extracted from their health records and analyzed. The location of the stroke patients were categorized by Local Governments Areas (LGAs). Spatial maps were generated and produced in a Geographical Information System (GIS) environment. It involves the analysis of the distribution of stroke cases in relation to their underlying population to determine the areas of high and low density of diagnosed cases across the state. Results The result highlighted the spatial distribution of diagnosed stroke cases and also highlighted the areas of concern regarding their spatial distribution within the state. Social inequalities in stroke were persistent as incidence rates in urban areas (North) were around 3 times higher than in the rural areas (South). However, this could be due to better healthcare access in the urban areas than in the rural areas as there were disparities in the distribution of healthcare facilities involved in administering care to stroke patients in Osun State. Conclusion The outcome of this study appears to indicate that spatial inequalities in the access to Stroke healthcare is a concern that needs to be addressed in order to manage the disease adequately.


Introduction
The rate at which people suffer from stroke disease in Nigeria is growing. Stroke ranked the number three (3) causes of death in Nigeria even in children, a serious economic burden [1]. Incidence of "Stroke" (Cerebrovascular Accident) in sub-Saharan Africa is alarming, an area where stroke units are largely not feasible and many patients do not reach the hospital [2,3]. It is also the leading cause of morbidity, mortality and disability in adults of productive ages that contribute the work force of the society [4]. High rates of hypertension, diabetes, alcohol abuse, smoking, insufficient fruit, and vegetables consumption, sickle cell disease, HIV infection, antiretroviral use and race are likely contributing factors [1,5].
There is evidence of geographical disparities for stroke disease worldwide. For instance, Southeast is reported in the United States with the highest risks [6]. The cluster of determinants of stroke at neighborhood level can greatly affect the planning, implementation and health focus initiatives that attempts to minimize disparities. A Statewide Stroke Incidence Information Registry could offer land administration officials the appropriate spatial information to focus efforts during medical and health care emergencies. This Statewide stroke disease database will create an exchange meant for sharing examples, ideas and techniques for informing policy and documenting geographical disparity, as it is now demonstrated in the western world such as the United States to reduce the prevalence of stroke. Also, population registry and property registry are linked together in Sweden so as to provide data for calculating distance network [7,8]. Geographical Information System (GIS) are increasingly used to analyze geographical distribution of disease as well as relationships with causative agents and their geographical environment [9]. Extensive review of previous studies has shown that even disease like stroke may have geographical influence and more accurate analysis using GIS technique can be generated. In the review of studies of geographies of declining stroke morbidity in the United States [10], it shows that such variation is typical of other countries.
The result show that the trend varies between age and sex groups in the population and that particularly with older people. Overall health gain across the country is being achieved at the cost of greater inequality in health between areas. Osun is one of the   disease among sampled patients ( Figure 6) revealed a trend of high levels of hypertension, and diabetes mellitus in the highest risk LGAs of Osun. The major predisposing risk factors are therefore, hypertension and diabetes mellitus.

Discussion
The focus of this paper is on the identified high risk areas for cardiovascular disease and healthcare facilities available for the management of the disease within Osun State. The study covers a spatial analysis of the distribution of diagnosed stroke cases in relation to their underlying population. The study was based on diagnosed cases from 1990 to 2012 acquired from ten available hospitals participating in delivering acute stroke care in the State.
Patients that were handled locally or with herbal approach and those who could not make it to the ten recognized hospitals in the case study area within the study period are not captured by this effort. It can be presumed that many stroke patients with symptoms of stroke were admitted to other hospitals especially when these hospitals were closer to them than the ten from which the data for this study was drawn. However, it is expected that these patients would be referred to any of the 10 hospitals for further treatment and as such their data would be captured in this study. But we can't rule out the possibility that some stroke patients never made it to any hospital. Therefore, the task of evaluating the spatial pattern of therefore, urgent attention is needed [12]. Given that stroke is uncommon among age group less than 30 years. This study indicated that stroke was more prevalent among those aged 75 years and older in Osun State. Furthermore, the trend was found to be high in adults of productive ages that contribute to the work force in Osun State, Nigeria (30 -69 years).
Studies indicate that sex discrepancies occur in patients with stroke as more males than females are diagnosed with stroke [13]. The result from this study also supports previous finding as males were approximately 56.4% and females 43.6%. However, when we estimated using total female and male population crude (all ages), males were 49.8% and females 50.2%. Furthermore, this study showed that, females were slightly younger than males therefore, using an adjusted population (30 years and above), males were slightly higher at 50% while females were 49%. The study also indicated that there were clustering of determinants of stroke at Ife Central, followed by Osogbo and Ifedayo Local Government Areas.
The study indicated that the increase is typical of urban settlements, as these areas tended to have high proportions of the population.

Conclusion
Statewide mapping of stroke incidence has reduced prevalence in developed countries due to life style modification and adequate health care planning [12]. Stroke disease in Osun State has been investigated in this study using a spatial approach. A combination of  There is evidence of geographical disparities for stroke disease worldwide but little is known within Nigeria.

What this study adds
 The study improves on the knowledge of the spatial distribution of diagnosed stroke cases within Nigeria;  Spatial inequalities in the access to Stroke healthcare is a concern that needs to be addressed in order to manage the disease adequately.

Competing interests
The authors declare no competing interests.

Authors' contributions
The authors generally worked as a team. The specific contribution to the work and write-up of the manuscript for each person is as follows. Ayila Emmanuel Adzandeh: data processing and spatial analysis; John Awope: majorly contributed in data acquisition and maps production; Osaretin Isoken Oviasu: compilation of results and report writing. All authors have read and agreed to the final version of this manuscript and have equally contributed to its content and to the management of the case.