A Systematic Review of Life Expectancy Differences and the Disease Cycle as a Major Predictor in Africa: The Nigeria Scenarios

Life expectancy and longevity constitute a very vital indicator of life events and disease conditions that individuals may have been exposed to at some points in their lifetime. Just like in other climes, in the African region life expectancy differ across a number of other socio-economic variables. This paper was designed to delineate some morbid determinants of such differences as they relate to observed disease pattern in Nigeria and the relationship between life expectancy and the disease cycle was also presented. It was shown that since 1900s average life expectancy worldwide has more than doubled to between 70 and 72 years, while the figure for the African region still falters at about 62.5 years. On the global scale, Nigeria ranks 177/178 for current life expectancy at birth. Based on age-standardized mortality rate per 100,000 of population ranking of the causes of death in Nigeria, topmost conditions include tuberculosis (1st), fall (2nd), maternal conditions (3rd), Pertussis (4th), and Diarrhoeal diseases (4th). In terms of percentage ranking of the causes of death in Nigeria, top on the list are Influenza and Pneumonia (15.03%), Diarrhoeal diseases (9.16%), Tuberculosis (8.62%), HIV/AIDS (8.31%), Malaria (5.53%), Low Birth Weight (4.30%), Stroke (4.10%), Birth Trauma (4.01%), Coronary Heart Disease (3.76%) and Maternal Conditions (3.14%). All of these offer differential explanation and contributions to variations in life span of the Nigerian populace. Apart from disease factors, this review showed that life expectancy in less developed countries (LDCs) like Nigeria, is affected by political and socioeconomic factors like theeconomy as measured by gross domestic product (GDP), educational environment indicated by the literacy rate, and nutritional status, measured by the proportion of undernourished. Hence, it is recommended that as a matter of urgency, concerned authorities should deploy multi-faceted interventions aimed at addressing the issues with poor life expectancy in Nigeria.

Key words: Disease cycle, Life expectancy, Nigeria.