Morbidity refers to the disease state of an individual, or the incidence of illness in a population. Mortality refers to the state of being mortal, or the incidence of death (number of deaths) in a population.
Certain diseases like cardiovascular problems, lung and blood diseases constitute a large proportion of causes of morbidity in individuals. A person can have several comorbidities at the same time which can range from Alzheimer’s disease to any injury or cancer.
Mortality rate can be distinguished into a crude death rate, which is the total death per year in the world; Perinatal mortality rate (neonatal and fetal deaths per year); Maternal mortality rate (number of deaths of mothers due to child bearing); Infant mortality rate (number of deaths of children less than one years of age) Child mortality rate (number of deaths of children less than 5 years old); Standardized mortality rate (adjusted according to the standard composition in terms of age, gender and other factors); and Age-specific mortality rate (total number of deaths of a particular given age).
edit Units of measurement
Morbidity scores or predicted morbidity are assigned to ill patients with the help of systems such as the APACHE II, SAPS II and III, Glasgow Coma scale, PIM2, and SOFA. Morbidity scores help decide the kind of treatment or medicine that should be given to the patient. Predicted morbidity describes the morbidity of patients, and is also useful when comparing two sets of patients or different time points in hospitals.
Mortality rates are generally expressed as the number of deaths per 1000 individuals per year.
The death rates and causes of it vary in different countries. The highest death rate according to statistics obtained by the CIA World Factbook (2009) has been reported for Swaziland at 30.83 deaths/1000 persons, followed by countries like Angola, Lesotho, Sierra Leone and Zambia. The leading causes of death are heart diseases, cerebro-vascular disease, respiratory infections, HIV/AIDS, COPD, and others. In third world countries, however, 58% of the mortality reported was due to malnutrition or deficiencies.
World Health Statistics (compiled by World Health Organization) contains a compilation of data pertaining to diseases, mortality, causes of death, and mortality rates. Publications like MMWR (Morbidity and Mortality Weekly Report, by Center for Disease Control and Prevention, USA), and databases like EMDB (European hospital Morbidity Database, Europe), and NHMD (National hospital morbidity Database, Australia) maintain patient health and disease records and health information and recommendations accessible to physicians, nurses, and other healthcare professionals.
The Human Mortality Database was developed by two groups –Department of Demography at the University of California, Berkeley and the Max Planck Institute for Demographic Research in Rostock Germany. This database provides mortality statistics and other population data for 37 countries to students and researchers and others interested.