**3. Burden and trends of NCDs in Africa**

The world health organization (WHO), defines NCDs as any medical condition or disease that is non-infectious and non-transmissible among people. The four main NCDs include cardiovascular diseases, chronic respiratory diseases, diabetes, and cancers which share a set of four key behavioral risk factors: tobacco use, harmful alcohol use, physical inactivity, and unhealthy diet [28]. These behaviors mediate biological risk factors such as obesity, raised blood pressure, and increased blood glucose, elevated blood lipids which ultimately progress to more advanced disease [29]. Other examples of NCDs include mental illnesses, injuries, and chronic kidney diseases. From 1990 to 2015, NCDs related deaths in SSA increased from 25% (1.7 million) to 34% (2.7 million). During the same period, the total NCD burden expressed as disability adjusted life years (DALYs) increased by 45% [7]. Cardiovascular diseases (CVDs) are the leading cause of NCD deaths. In 2013, CVDs caused nearly 1 million deaths in SSA, constituting 38.3% of non-communicable disease deaths and 11.3% of deaths from all causes in the region [30]. Cancers come second causing 12% NCDs deaths with wide variations across regions in SSA. Among males in SSA, leading cancer cases (in age-standardized incidence rate (ASIR) per 100,000 population) included, prostate cancer (27.9), liver cancer (10.2), Kaposi sarcoma (7.2), oesophageal cancer (6.8) and colorectal cancer (6.4). While among females, cervical cancer (34.8), breast cancer (33.8), liver cancer (5.4), colorectal cancer (5.4), ovarian (4.6) [31], are the most common causes of death. Tragically, survival from cancer is worse than in the rest of the world. For many cancers, the risk of getting cancer and the risk of dying from it are nearly the same in SSA [32]. Chronic respiratory diseases and diabetes are each responsible for about 10% and 5% of total deaths in SSA respectively [7]. The NCD risk factors such as high blood pressure, poor diets, air pollution, high body-mass index, tobacco smoking, alcohol and drug use, high fasting plasma glucose, high total cholesterol, and low physical activity are the top 10 global risk factors for death [7].

Other forms of NCDs such as injuries are responsible for a significant proportion of DALYS. Injuries resulting from road accidents (motor vehicles and motor bikes) have increasingly taken a growing toll on human health [33]. Mental disorders, including depression and anxiety, or severe forms like psychosis, schizophrenia and bipolar, as well as alcohol and substance dependence are common. Over the next decade, it is projected that NCD associated DALYs will surpass that contributed by infectious diseases, perinatal and maternal conditions combined (**Figure 3**)**.**

**35**

*Non-Communicable Diseases and Urbanization in African Cities: A Narrative Review*

Hypertension is a leading risk factor for mortality, and is the prime risk factor for the CVD epidemic in Africa [34]. Hypertension is defined as an average systolic blood pressure ≥140 mmHg and/or average diastolic blood pressure ≥90 mmHg among adults aged at least 18 years. Data available on hypertension prevalence are from a wide range of studies [35, 36], majority of which are not age-standardized, and this limits the opportunity for reliable comparison between different African countries and cities. Nevertheless, several WHO STEPwise surveys reported a hypertension prevalence of 19.3–39.6% in Africa [35, 37]. Additional data from epidemiological modeling project suggest that 216.8 million people will have hypertension by 2030. Urban settings consistently have a higher prevalence of hypertension

*Projected burden of disease in SSA, 2008 and 2030. Source of data: Authors from (World Health Organization,* 

*2008). NCDS\*: Cardiovascular diseases, cancer, diabetes, chronic respiratory diseases.*

Of great concern, is the proportion of individuals with hypertension who remain underdiagnosed, lack access to treatment and are prone to severe complications and increased risk of premature deaths [40]. Evidence from a review of hypertension in 23 African countries, shows that less than half of those with hypertension are aware of their diseases and only one third of those who are aware start treatment, and less than 10% of those on treatment have their blood pressure controlled [41]. It is thus crucial to understand the risk factors driving the rise of hypertension in urban areas to inform preventive interventions. Several factors have been cited as responsible

Early studies by Donnison et al. (1929) in an African rural community established the role of civilization and urbanization on the development of hypertension [42]. Later, Poulter et al. (1990) established social-behavioral origins with sedentary lifestyles and increased consumption of unhealthy diets among rural– urban migrants in Kenya as major factors driving elevated blood pressure [43]. Researchers also observed that mean diastolic blood pressure of migrants (aged 15–34 years) who moved to the cities increased markedly over time, compared to

*DOI: http://dx.doi.org/10.5772/intechopen.89507*

**4. Hypertension in African cities**

**Figure 3.**

compared to rural areas [38, 39] (**Figure 4**)**.**

for the rise of hypertension among urban populations in Africa.

*Non-Communicable Diseases and Urbanization in African Cities: A Narrative Review DOI: http://dx.doi.org/10.5772/intechopen.89507*

**Figure 3.**

*Public Health in Developing Countries - Challenges and Opportunities*

**3. Burden and trends of NCDs in Africa**

*A section of the Nairobi Central Business District (CBD).*

**Figure 2.**

The world health organization (WHO), defines NCDs as any medical condition or disease that is non-infectious and non-transmissible among people. The four main NCDs include cardiovascular diseases, chronic respiratory diseases, diabetes, and cancers which share a set of four key behavioral risk factors: tobacco use, harmful alcohol use, physical inactivity, and unhealthy diet [28]. These behaviors mediate biological risk factors such as obesity, raised blood pressure, and increased blood glucose, elevated blood lipids which ultimately progress to more advanced disease [29]. Other examples of NCDs include mental illnesses, injuries, and chronic kidney diseases. From 1990 to 2015, NCDs related deaths in SSA increased from 25% (1.7 million) to 34% (2.7 million). During the same period, the total NCD burden expressed as disability adjusted life years (DALYs) increased by 45% [7]. Cardiovascular diseases (CVDs) are the leading cause of NCD deaths. In 2013, CVDs caused nearly 1 million deaths in SSA, constituting 38.3% of non-communicable disease deaths and 11.3% of deaths from all causes in the region [30]. Cancers come second causing 12% NCDs deaths with wide variations across regions in SSA. Among males in SSA, leading cancer cases (in age-standardized incidence rate (ASIR) per 100,000 population) included, prostate cancer (27.9), liver cancer (10.2), Kaposi sarcoma (7.2), oesophageal cancer (6.8) and colorectal cancer (6.4). While among females, cervical cancer (34.8), breast cancer (33.8), liver cancer (5.4), colorectal cancer (5.4), ovarian (4.6) [31], are the most common causes of death. Tragically, survival from cancer is worse than in the rest of the world. For many cancers, the risk of getting cancer and the risk of dying from it are nearly the same in SSA [32]. Chronic respiratory diseases and diabetes are each responsible for about 10% and 5% of total deaths in SSA respectively [7]. The NCD risk factors such as high blood pressure, poor diets, air pollution, high body-mass index, tobacco smoking, alcohol and drug use, high fasting plasma glucose, high total cholesterol, and low physical activity are the top 10 global risk factors for death [7]. Other forms of NCDs such as injuries are responsible for a significant proportion of DALYS. Injuries resulting from road accidents (motor vehicles and motor bikes) have increasingly taken a growing toll on human health [33]. Mental disorders, including depression and anxiety, or severe forms like psychosis, schizophrenia and bipolar, as well as alcohol and substance dependence are common. Over the next decade, it is projected that NCD associated DALYs will surpass that contributed by infectious diseases, perinatal and maternal conditions combined (**Figure 3**)**.**

**34**

*Projected burden of disease in SSA, 2008 and 2030. Source of data: Authors from (World Health Organization, 2008). NCDS\*: Cardiovascular diseases, cancer, diabetes, chronic respiratory diseases.*
