Morbidity and Mortality

Morbidity and mortality are two very important aspects of medical surveillance. They are primary indicators of the healthiness or sickness of a population.

Any disturbance in the function or structure of a human body is considered to be a disease. Disease, illness, injury, disorder, and sickness all are categorized under a single term, morbidity. Morbidity is the extent of disease, illness, injury, or disability in a defined population. It is either a deviation from a state of health and well-being or the presence of a specific symptom or condition. Morbidity is usually expressed in terms of prevalence, attack rates, or incidence rates. In essence, morbidity refers to the rate of disease in a population—in other words, the number of ill people present in a certain population that is healthy but at risk for developing the disease.

Mortality means death, or it describes death and related issues. The mortality rate is the rapidity with which people in a given population die of a particular condition. Three things generally cause death: degeneration of vital organs and related conditions; specific disease states; and massive trauma or physical harm caused by environmental or social conditions, such as accidents, disasters, and homicides.

Numerical information about death is a basic component of vital statistics and epidemiology. In many countries, laws require the registration of vital events, including births, marriages, divorces, and deaths. Mortality rates are the foundation for vital statistics. Deaths are certified by a physician or a coroner; they must be recorded and reported to local health departments or state offices of vital statistics. On a death certificate, the cause of death is stated, or an underlying cause of death can be noted.

Mortality statistics are reported from the information recorded on death certificates. Public health agencies and other organizations (e.g., insurance companies) produce and revise tables of mortality that are published on a regular basis. These tables of mortality provide actual numbers of deaths as well as death rates by age, sex, and cause of death. Special mortality tables can also present other variables in the context of vital statistics. Examples of different types of mortality rates include annual death rate, infant mortality rate, fetal death rate, abortion rate, maternal mortality rate, and case fatality rate.