Noncommunicable diseases are usually thought of as chronic conditions that do not result from an acute infectious process. These conditions cause death, dysfunction, or impairment in the quality of life, and they usually develop over relatively long periods—at first without causing symptoms; but after disease manifestations develop, there may be a protracted period of impaired health. Generally, these conditions or diseases result from prolonged exposure to causative agents, many associated with personal behaviors and environmental factors. The major noncommunicable diseases are listed in Tables 1 and 2. Noncommunicable diseases also include injuries, which have an acute onset, but may be followed by prolonged convalescence and impaired function, as well as chronic mental diseases.
Noncommunicable diseases are the leading cause of functionary impairment and death worldwide. These conditions have been the leading cause of death in the United States and other high-income countries over the last fifty years, and they are emerging as a leading cause of death in low-to middle-income countries. Table 1 depicts the leading causes of death worldwide showing that noncommunicable diseases and injuries account for
Causes of Death Worldwide: Estimates for 1999 (in thousands)
SOURCE: Adapted from The World Health Report 2000: Health Systems: improving performance. Geneva: World Health Organization, 2000.
over two-thirds of deaths. In addition, these diseases cause pain, disability, loss of income, disruption of family stability, and an impaired quality of life.
Disability-adjusted life years (DALYs) constitutes one means of assessing the effect of disease, as shown in Table 2. (DALYs are a measure accounting for years of life spent with diminished function resulting from health conditions of varying severity.) Over the past century, dynamic changes have occurred in the worldwide prevalence of noncommunicable diseases, and even more rapid transitions are expected in the twenty-first century. These changes have been driven by social, economic, and public health progress, and the strategies for change have been illuminated by research.
WILLIAM R. HARLAN, LINDA C. HARLAN, The Gale Group Inc., Macmillan Reference USA, New York,