The United States: In 1900, the most common causes of death were infectious diseases, which brought death quickly. Today, the most common causes of death are chronic diseases in which a slow and steady decline in health ultimately results in death. In 2015, heart disease, cancer, and chronic lower respiratory diseases were the leading causes of death (see Figure 10.2, CDC, 2016).

Figure 10.2 Leading Causes of Death in the United States in 2015

The causes of death vary by age (see Tables 10.1 and 10.2; adapted from CDC, 2015). In infancy, congenital problems and other birth complications are the largest contributors to infant mortality. Accidents, known as unintentional injury, become the leading cause of death throughout childhood and early adulthood. In middle and late adulthood cancer and heart disease become the leading killers.

Table 10.1 Top Five Causes of Death in the United States in 2013 by Age (birth to 24)

The world: The most recent statistics analyzed by the World Health Organization were in 2012, and non- communicable deaths; that is, those not passed from person- to-person, were responsible for 68% of deaths (WHO, 2016). The four most common noncommunicable diseases were cardiovascular disease, cancer, diabetes, and chronic lung diseases. In contrast, communicable diseases, such as HIV and other infectious diseases, neonatal and maternal mortality, and nutritional problems caused 23% of the deaths, and injuries caused the remaining 9% of the deaths.

Tobacco use is attributed as one of the top killers, and is often the hidden cause behind many of the diseases that result in death, such as heart disease and chronic lung diseases (WHO, 2016).

These statistics hide the differences in the causes of death among high versus low income nations. In high-income countries, defined as having a per capita annual income of $12,476 or more, 70% of deaths are among people aged 70 and older. Only 1% of deaths occur in children under 15 years of age. People predominantly die of chronic diseases, such as cardiovascular disease, cancers, dementia, or diabetes. Lower respiratory infections remain the only leading infectious cause of death in such nations. In contrast, in low-income countries, defined as having a per capital annual income of $1025 or less, almost 40% of deaths are among children under age 15, and only 20% of deaths are among people aged 70 years and older. People predominantly die of infectious diseases such as lower respiratory infections, HIV/AIDS, diarrheal diseases, malaria and tuberculosis. These account for almost one third of all deaths in these countries. Complications of childbirth due to prematurity, birth asphyxia, and birth trauma are among the leading causes of death for newborns and infants in the poorest of nations (WHO, 2016).