Epidemiology of cardiovascular disease risk factors in Ethiopia : the rural-ruban gradient

Abstract: BackgroundChanges in the population structure and the main causes of death result in the growing burden of chronic diseases, which characterize the epidemiological transition. The transition takes place at different paces in different parts of the world. The developed world has taken over a century to complete the transition, and the rapidly developing countries of Asia and Latin America are undergoing a swift transition. In contrast, many sub-Saharan African countries are said to be experiencing a delayed transition. In Ethiopia, routine health care reports are incomplete and erratic. Lack of nationwide data on causes of death clouds understanding of the burden of disease or its composition. Consequently, there is limited knowledge on the course of the epidemiological transition, which has left room for widespread scepticism concerning the importance of chronic diseases in the country. Hence, the health system continues to be heavily reliant on the conventional “infectious disease paradigm”, and fails to be responsive to emerging health problems. Assessing the pattern and causes of disease burden enables meeting the health care needs of vulnerable population segments and devising cost-effective interventions that avert the impact of emerging diseases on the health and well-being of the nation. However, in countries without a functional system for registration of vital events, such as births and deaths, complete and reliable data on the burden of chronic diseases will not be available. Data on their risk factors, which are valuable for prevention and control programmes, can be generated through population-based surveillance, and serve as a practical alternative.ObjectivesThis research project was implemented in order to illustrate the distribution of risk factors for cardiovascular diseases (CVD), and examine the gradient across urban and rural populations in Ethiopia, thereby contributing to national and global efforts of tracking the course of the epidemiological transition.MethodsThe WHO STEPS instrument was employed in two populations of central Ethiopia, representing a predominantly rural district (Butajira) and the national capital – Addis Ababa. Over 8000 adults in the age group 25-64 years, from the two populations, participated in interview and physical measurements, which were conducted in a standard manner. Ethical clearance for the project was obtained from appropriate national bodies and ethical conduct was maintained throughout the research process.ResultsThe findings revealed wide disparities, between urban and rural populations, in the distribution of the main risk factors of CVD. Elevated blood pressure, obesity, and physical inactivity were more concentrated in urban populations, while the rural-urban gap was narrower with the distribution of cigarette smoking and binge drinking of alcohol. The use of substances like khat (Catha edulis Forsk), which may increase the risk of acute myocardial infarction, is expanding from rural areas that grow the plant to urban populations, partly due to improved transportation and market forces. The gap in the distribution of risk factors between the sexes is wider in rural populations and narrows down in urban areas. Thus, men in rural areas have a markedly higher prevalence of hypertension than women, while the level is similar between men and women in urban areas. Urban women carry more risk of CVD due to higher prevalence of physical inactivity, overweigh and obesity. Intake of fruits and vegetables is not consistent with optimal cardiovascular health in both rural and urban populations, but comparatively better in rural areas.Conclusion and recommendationsThe prevalence of high blood pressure in urban Ethiopia is similar to other sub-Saharan African countries, and closely comparable to the situation in the developed world. Owing to the established contribution of high blood pressure to CVD morbidity and mortality, it (elevated blood pressure) may represent the principal risk factor for CVD in the Ethiopian population, particularly in urban areas. Programmes for the prevention and control of CVD in Ethiopia should give due priority to the prevention of high blood pressure and its precursors, such as physical inactivity, overweight and obesity. Population wide strategies should be implemented to promote healthy dietary behaviour and physical activity, and to prevent smoking and substance use behaviours. Programmes should also aim to improve awareness, detection and appropriate clinical management of high blood pressure among health care providers and the public at large. The stepwise surveillance of chronic disease risk factors (STEPS) should be implemented on a sentinel nationwide basis in Ethiopia, in order to inform policy and guide strategies and programmes for the prevention and control of CVD and other chronic diseases. The national health extension program offers an opportunity to establish a system for registration of birth, death, and similar vital events at a population level, which provides a more reliable foundation for estimating vital indicators and disease burdens.