Cardiovascular System Mortalities in Nigeria; Case Study of the University of Port Harcourt Teaching Hospital

Background: Studies have suggested epidemiological transition in the mortality pattern in Nigeria from communicable to non-communicable diseases of which Diseases of the cardiovascular system (DCVS) is prime. DCVS is thus a growing public health concern but its mortality profile is under-studied in Port Harcourt. This study was therefore designed to review the mortality profile of DCVS in Port Harcourt. Methodology: A retrospective case con-trolled study of deaths ascribed to DCVS at the University of Port Harcourt Teaching Hospital (UPTH) between January 2012 and December 2017. The composite diseases were grouped using the ICD10 scheme and analyzed using SPSS version 23. Minitab version 16 was used for trend analysis. Results: Of the overall 1902 deaths recorded within the period, 566 (29.8%) were cardiovascular system related. Of these, 301 (53.3%) were males and 265 (46.7%) were females. The elderly of 50 - 99 years were most commonly affected (65.5% of the mortalities). Cerebrovascular accidents (CVA) accounted for 322 deaths (56.9%); various types of shock caused 116 deaths (20.5%) while congestive cardiac failure (CCF) accounted for 114 deaths (20.1%). Pulmonary embolism, myocardial infarction, carotid aneurysm, and hypertensive encephalopathy caused 1.8%, 0.4%, 0.2%, and 0.2% deaths respectively. Peak annual mortality of 143 (25.3%) was recorded in 2013. Although the trend of mortality was undulating, there was an overall increase in annual incidence over the years. Conclusion: DCVS constitute the commonest systemic cause of death in Port Harcourt. Governmental and donor agencies involved in public health policy planning and implementation should scale-up strategies for the prevention and control of DCVS in order to stem the rising tide of associated mortalities.


Introduction
Diseases of the cardiovascular system (DCVS) constitute enormous public health challenges [1] and contribute significantly to the burden of non-communicable diseases in sub-Saharan Africa [2]. WHO has reported that 17.9 million (31%) deaths are annually recorded globally from DCVS [3]. About 75% of these deaths occur in low and middle-income countries [4]. Although diseases of the cardiovascular system was reported as the second commonest cause of death after infectious diseases in Africa, current projections hold that an increase of 20% is expected by 2020 and the greatest burden likely to be experienced in enormous public Africa [5] [6] [7]. Consistent with this notion, other reports have stated that in most developing countries including Nigeria, deaths from non-communicable diseases like DCVS and cancers are on the rise while communicable diseases like infectious diseases are on the decline [8] [9] [10].
In Sub-Saharan Africa generally, including Nigeria, the current rise in DCVS is attributable to some modifiable risk factors, including rapid urbanization, effects of globalization and poverty especially among residents of urban areas [11] [12]. Also, the resultant preference for energy-dense and processed foods in lieu of traditional diets of natural composition, devoid of additives and colorants is a risk factor for the development of DCVS [13]. Other primary risk factors causing cardiovascular system-related deaths include; hypertension, diabetes, alcohol abuse, tobacco abuse, obesity and lack of physical exercise [14] [15]. Mortality due to DCVS significantly increases socio-economic costs, loss of productivity, disability and remains a contributing factor to health inequalities and poverty in developing countries [14].
The specific causes of mortalities associated with DCVS show significant global variation. For instance, among the developed countries, coronary-artery diseases remain the main cause of death while in sub-Saharan Africa, stroke is the leading cause of death followed by hypertensive heart diseases and heart failure [16].
Previous hospital-based studies identified hypertension as the commonest cause of cardiovascular mortality in Nigeria [17].
As the people of Nigeria gradually goes through epidemiologic transition with increasing burden of non-communicable diseases like DCVS, Port Harcourt, with cosmopolitan settlement sequel to decades of oil and gas activities that attract people of multiple races, nationalities, and tribes deserves an evaluation of the profile of cardiovascular system mortality.
The objective of this study is to determine the trend and causes of deaths due to diseases of the cardiovascular system at the University of Port Harcourt Teaching Hospital.

Methodology
This six-year retrospective case-controlled study was carried out at the University of Port Harcourt Teaching Hospital (UPTH), Port Harcourt, Nigeria. UPTH with a bed capacity of 882, is the foremost tertiary health institution in Rivers C. C. Obiorah World Journal of Cardiovascular Diseases state serving as the major referral center for residents of the State. It also serves some residents from the neighboring states of Bayelsa, Abia, Imo, and Akwa Ibom-all in the oil-rich Niger Delta region of Nigeria [18]. In all, UPTH serves a population of not less than 10 million. Death registers, available case notes and death certificates of those who were managed for DCVS between January 2012 and December 2017 were selected and further reviewed.

Results
Mortalities from DCVS constituted 566 (29.8%) of the overall 1902 mortalities recorded within the study period. There was a slight predominance of males-301 cases (53.3%) over females with 265 cases (46.7%). Peak mortality for males and females was observed in 2013 ( Figure 1). The incidence increased with age till the bimodal peak ages in the 6 th and 7 th decades with the occurrence of 120 cases (21.2%) and 119 cases (21.0%) respectively ( Table 1). The annual mean ages range from 50.9 to 58.4 years with an overall mean age of 54.5 ± 18.09 years ( Table 2). The average of the median ages was 56 years while the annual range was 49 -61 years. The mean age for female decedents was 53.2 ± 19.1 while for the males it was 56.0 ± 17.1. For young adults aged 20 -39 years, DCVS predominated among the females while for those aged above 40 years, there was a predominance of DCVS among the males (Table 1)

Discussion
Mortality data serve as an important indicator of the health status of a people and constitutes an indispensable factor in public health programming and planning. It assists policymakers to focus on key areas of intervention [19]. [33] [34]. Factors such as age, hypertension, total cholesterol, and low-density lipoprotein have a greater effect on men thereby predisposing them to more cardiovascular risks [35]. Women have also been reported to have better control of hypertension than men thereby reducing the risk of mortality from DCVS [36] [37]. Another explanation to the higher DCVS mortality in males in our study stems from their predisposition to other common risk factors such as smoking, heavy drinking, poor dietary habit [38] and diabetes [39]. We also add that the state of Nigeria's economy and the associated pervading poverty tends to keep the majority of men on their toes, attempting to make ends meet for their families where they are breadwinners. This predisposes them to psychological and emotional stress and frustration, especially for those who are unable to meet up to the expected family and societal demands. In line with our thought, Steyn et al. in their interheart African study identified smoking and permanent stress as the strongest risk factors of cardiovascular diseases among Africans [31]. However, for younger decedents 20 -39 years, mortality was noted more among females. The reasons for this twist in the gender trend are not clear but may be related to the general prevalence of obesity which is a strong risk factor for cardiovascular diseases among females in Nigeria [40].
The proportion of recorded deaths among children and adolescents aged 0 -19 years was 4%. This is higher than 0.7% mortality from DCVS reported among children of the same age range in hospital-based study in south Eastern Nigeria by Arodiwe et al. [41]. The commonest causes of DCVS mortality in our study was the shock of various types (42.9%) and CCF (33.3%) ( Figure 3). This further goes to show that it could be as a result of diarrhoeal diseases and other infective conditions that could end in septic shock. The heart failures could be associated with anaemia often resulting from several illnesses encountered in children commonest of which is malaria.
The overall mean age was 54.5 years which is similar to the 54.9 years reported in Ibadan by Adedapo et al. [32] The people of the mean age group constitute the bulk of experienced workforce and captains of businesses. Therefore their demise definitely impacts negatively on the economy and creates vacuum in families with attendant multiplier effects on the already bad societal poverty. A study by the American heart association put the indirect costs of lost earnings and household productivity from premature death due to cardiovascular system diseases at 237 billion dollars [42]. on Coronary Heart Disease in Nigeria that CHD is relatively uncommon in Nigeria and therefore does not contribute significantly to morbidity and mortality from cardiovascular diseases but also call to question the diagnostic capacity of most facilities in Nigeria for both acute and chronic CHD [44]. It is possible that the disorder is under-diagnosed and therefore under-reported.
The trend was undulating with a peak occurrence in 2013 and least in 2012.
Short of the spike in 2013, the course and trend showed a steady upward swing.
This is similar to reports from other centres across Nigeria that indicate a rising incidence of DCVS.
This study was limited by the non-autopsy confirmation of the causes of death and dependence on clinical diagnoses based data only. The general poor recordkeeping attitude of the hospital has not helped the situation either as it is possible that some cases were missed out.

Conclusion
This study shows an epidemiologic shift from infectious causes to DCVS as the commonest causes of mortality for admitted patients in UPTH Port Harcourt.
The demise of people of the mean age of 54 years owing to DCVS impacts negatively on the economy and creates a vacuum in families with attendant multiplier effects on the already bad societal poverty. There is, therefore, a need to aggressively develop and implement health programs and interventions that can help reduce risk factors especially for cerebrovascular accidents, which was the most common cause of DCVS mortality observed; while enhancing the documentation of mortalities resulting from these diseases for tracking of the effectiveness of instituted intervention measures.