Lifestyle diseases could scupper Africa's rising life expectancy
People in sub-Saharan Africa are now living longer than ever before. A child born in the region today is expected to live up to 64 years on average. This is a remarkable increase of 11 years since the year 2000, when life expectancy at birth was only 53 years in sub-Saharan Africa.
Life expectancy at birth is the average number of years that a newborn is expected to live, if current mortality rates hold steady. Changes in life expectancy can be used to track the impact of population-wide health threats, such as the HIV epidemic in sub-Saharan Africa. The monitoring of life expectancy can also provide crucial information that's needed to deploy resources and effective interventions on the ground.
The life expectancy improvements in sub-Saharan Africa vary between men and women, within sub-regions and between countries.
We know all of this, and much more, because of an extensive study we recently published in The Lancet. We drew from the Global Burden of Disease study, which is a systematic effort to gather and analyse a huge amount of data on health loss due to diseases, injuries and risk factors by age, sex and geography over time. This allowed us to look at trends in mortality and life expectancy in the region from 1950 to 2017. It's the most comprehensive look at these issues that's ever been published.
Our research shows that the average life expectancy for men in sub-Saharan Africa is 62 years. For women it's 66 years.
There are regional variations too. For example, men in central Africa will live to 60; those in eastern Africa to 63. Women in central Africa will reach 64 years; in southern Africa the figure is 68 years. The lowest life expectancy among men in sub-Saharan Africa is 49 years in the Central African Republic. The highest – 73 – is in Cape Verde. The corresponding life expectancy for women in those countries is 55 and 79 years.
There has been a huge decrease in mortality among children younger than five in sub-Saharan Africa. As a portion of total deaths, the number of deaths before the age of five has decreased from 45% in 1950 to 10% in 2017.
This is likely linked to a number of interventions such as the scale-up of vaccination programmes, improved water and sanitation, and mass distribution of insecticide-treated bed nets. Mothers' increased education levels and rising individual incomes have also contributed to the decrease in child deaths.
But caution is necessary. It's not inevitable that death rates will keep falling. Rising epidemics of high blood pressure, high blood sugar, and obesity in some African countries could lead to shifts over time in the opposite direction.
Falling death rates
Overall, death rates have been dropping in sub-Saharan Africa since the beginning of the 21st century. There were 702 deaths per 100 000 people in 2017, down from 1366 deaths per 100 000 in 2000.
For all ages, it's estimated that one-third of life expectancy improvements are because of rising income per capita, one-third can be attributed to improvements in educational attainment, and one-third are a result of changes that have happened over time. These include technological improvement such as new vaccines. We have also learned more about diseases and how to control them.
There may be additional reasons for the reductions in mortality over time. These would include social factors like availability of job opportunities and good working conditions, existence of social support networks, and safe housing.
Causes of death
The five leading causes of death in sub-Saharan Africa for adults between the ages of 15 and 49 years in 2017 were AIDS, tuberculosis, malaria, maternal disorders, and road injuries.
The leading causes of death differed when we looked at mortality for each of the sexes over time. There were major changes in the leading causes of death between 1990 and 2017.
Interpersonal violence was the seventh leading cause of death among men in 1990. Now it's number five. Liver cirrhosis was the eighth leading cause of death; now it's the sixth.
The main changes in causes of death among women were cervical cancer, which moved from 10th in 1990 to seventh. Breast cancer was the 17th leading cause of death among women – today it is eighth.
For people between the ages of 50 and 69, the three leading causes of death in 2017 were tuberculosis, heart attacks and stroke among men; and stroke, heart attacks and tuberculosis among women.
This shows that non-communicable diseases are already wreaking havoc in many countries across the continent.
High blood pressure, high blood sugar, and obesity are the top risk factors for death in women aged between 50 and 69. The top risk factors for men in the same age group are high blood pressure, high blood sugar, and alcohol use (with obesity in sixth position).
These risk factors are warning signs of an impending, widespread epidemic of non-communicable diseases in sub-Saharan Africa. Some non-communicable diseases such as diabetes, heart attacks, and stroke are already projected to be major killers in the region soon.