CHAPTER ONE

INTRODUCTION

1. Background

According to WHO, stroke is defined as “a focal (at times global) neurological impairment of sudden onset, and lasting more than 24hrs (or leading to death) and of presumed vascular origin”.

The American heart association and American stroke association (AHA/ASA) contributed to this definition by adding some pathological and neuroimaging modalities. Given the fact that reduced blood supply to the brain can lead to reversible or irreversible changes, the gravity of these changes depends on the duration of deprivation, and it varies according to individuals. Permanent changes will occur in term of minutes in some people, or it might take hours to days in others.

That’s why the stroke council of the AHA/ASA adopted a new definition of stroke in 2013, it is defined as:  “CNS infarction is brain, spinal cord, or retinal cell death attributable to ischemia, based on pathological, imaging, or other objective evidence of cerebral, spinal cord, or retinal focal ischemic injury in a defined vascular distribution; or clinical evidence of cerebral, spinal cord, or retinal focal ischemic injury based on symptoms persisting ≥24 hours or until death, and other etiologies excluded.” [1]

Stroke is the 2nd leading cause of death and disability worldwide. [2] In 2015, we accounted about 17 million new cases of stroke globally, one case of stroke every two seconds.[3] In 2016, the world prevalence of stroke was 80.1 million total cases. Stroke was reported as 2nd most common cause of death worldwide after ischemic heart disease, with a total of 5.5 million deaths.

The same year, stroke was also identified as the 2nd cause of global Disability adjusted life years (DALYs) in the world after ischemic heart disease and followed by lower respiratory tract infection.[2] The incidence of stroke is on the rise globally due to the aging population.[4] During the year 2016, in North America there were 812 285 new cases of stroke, 195 661 deaths from stroke and a total of 3 451 975 DALYs due to stroke. In Latin America there were 620 201 new cases, 4 674 275 DALYs and 221 264 deaths.

In Europe, there were 2 466 197 new cases, a total of 15 556 564 DALYs and 948 896 deaths from stroke. Asia had a total of 8 549 914 new cases, 77 941 339 DALYs, and 3 542 107 deaths. In Africa we had 769 935 new cases of stroke during the same year, 10 325 248 DALYs, and 429 388 deaths from stroke. Sub-Saharan Africa beared the highest mortality in the continent with a total of 320 437 deaths, as well as the highest incidence and number of DALYs: 519 330 and 7 969 485 respectively. In Cameroon, we had 12 801 new cases, 234 925 DALYs and 9091 deaths from stroke the same year.[2]

Many studies have been conducted all around the world, and they reported that 90% of the global burden of stroke were attributable to modifiable risk factors.[5–7] The latter are 10 in number: hypertension, smoking, abdominal obesity, poor diet, physical inactivity, diabetes mellitus, alcohol intake, psychosocial factors (stress, depression), cardiac diseases, and dyslipidemias.[2, 5–7] Hypertension carries the heaviest load according to many studies, and has been identified as the most severe risk factor for all stroke subtypes, but more for hemorrhagic stroke than for ischemic stroke.[2,5–8] hypertension was also reported as been more prevalent in subjects of 45 years or younger.[2, 5–7] Hypertension, psychosocial factors, and alcohol intake greater than 30 drinks per month predisposes more to hemorrhagic stroke.

Smoking, Atherosclerosis, Atrial fibrillation, dyslipidemias and diabetes mellitus were more attributable to ischemic stroke. Obesity and poor diet were attributable to both types.[2, 4–6, 8] These risk factors have been reported as been the same for high, middle, and low middle income countries.[5–7] According to WHO, Africa carries the greatest burden of hypertension.[9] Africans have been linked to have and be predisposed to higher risk of stroke, to have a greater proportion for hemorrhagic stroke and to suffer more severe complications of stroke.[10–16]

Ischemic and hemorrhagic stroke are the two major stroke types existing.[3] There is an intercontinental variation in the proportion of stroke type. Ischemic stroke represents more than 80% of strokes in western countries.[17] The proportion of ischemic stroke in China varies between 43.7% to 78.9%.

In some studies hemorrhagic stroke represented up to 55.4% of all stroke.[18] a study conducted in Guinea-Conakry reported a prevalence of 74% for ischemic stroke.[19] In Cameroon, the proportion of  ischemic stroke varies between 52% and 60% according to some studies.[20,21] Though ischemic stroke is more prevalent than hemorrhagic stroke, higher mortality rates and more severe disabilities have been linked with hemorrhagic stroke.[8, 19]

Stroke is not only a burden in terms of human resources but also economically. In 2015, the AHA reported that 72 billion dollars were spent on stroke annually.[17] This amount is projected to triple to 184.1 billion dollars between 2012 and 2030.[22] In Europe the annual cost of stroke was estimated to be 29.8 billion dollars in 2010. In 2011, the annual cost of stroke in china was estimated to be about 6.3 billion dollars.[23] From 2016 to 2017, a study conducted in Dakar reported and average cost of stroke per patients of 766 dollars, it was higher for hemorrhagic stroke (939 dollars) compare to ischemic stroke (664 dollars).[24] In Cameroon, a study conducted from the year 2012 till 2013 in Douala reported that an amount of 103 000 dollars, with an average cost of 1364 dollars spent individually.[25]

Stroke disparities are present and real worldwide, especially in low and middle income countries.[4] Inability to access medical care, limited trained professionals, insufficient literature,  infrastructures and equipments, all limit the effectiveness of prevention in stroke care, particularly in low and middle income countries.[4, 26] A recent AHA/ASA consensus panel concluded that: “racial and ethnic disparities in stroke exist and include differences in the biological determinants of disease and disparities throughout the continuum of care, including access to and quality of care.

Access to and participation in research is also limited among minority groups. Acknowledging the presence of disparities and understanding the factors that contribute to them are necessary first steps.”[27–29] In Cameroon, the existing multicultural background, the socioeconomic disparities present its regions and the current security crisis the country is facing, all may influence the knowledge, management as well as the outcome of stroke in those areas. We therefore seek to carry out this study in two hospitals of a semi-urban area affected by civil war, and a tertiary hospital of an urban area.

1.2 Problem Statement

The incidence of stroke, is increasing in low and middle income countries, especially in Africa. More than 80% of all stroke deaths around the world are found in LMIC including Africa.[16] Low levels of knowledge regarding cerebrovascular diseases were found in a population in South-West Cameroon.[30] Stroke in the DGH is associated with a high mortality rate and hypertension remains the number one risk factor.[20]

Few studies have been conducted on stroke in semi-urban areas worldwide, particularly in our country and especially in their hospitals. Human resources are limited, there is a scarcity of neurologists in semi-urban areas. There are no stroke units in both semi urban and urban areas, and there exist a significant gap in the management of patients in hospitals of semi-urban areas versus those of urban areas. There is no stroke guideline in Cameroon.

1.3 Research Goal

The goal of this study is to improve on the prevention and management of stroke according to local realities faced by population of both semi-urban and urban areas.

1.4 Research Questions

1. What is the hospital-based prevalence of stroke in urban and semi-urban areas?
2. What are the Sociodemographic characteristics, and identified risk factors of stroke among patients of both areas?
3. What are the differences in the outcome of stroke in patients of these areas?

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