This paper describes the evolution of disease frequency statistics and techniques used to present them. Beginning in the 17th century with the first specific references to causes of death and proceeding practically until the mid-20th century as mortality statistics by causes, the instrument for a methodical description of diseases was classification of causes of death. From the latter half of the 20th century on, in addition to mortality statistics by cause, morbidity statistics became routine, with the adoption of disease classification and no longer only classification by cause of death. More recently, classification has been adapted to medical specialties, resulting in what has been termed "disease family classification", including classification of the consequences of diseases, with statistics on disability. Disease classification, both for mortality and morbidity, fostered the development of various types of epidemiological studies (both descriptive and analytical) that expanded knowledge on health.
Diseases Classification; Mortality; Morbidity
