ICD-6 and the classification of illness

For half a century the international list counted only deaths. In 1893 Jacques Bertillon, chief of statistical services for the City of Paris, presented a classification of causes of death to the International Statistical Institute meeting in Chicago. It kept William Farr's principle of separating general diseases from those of a particular organ or site. Revision conferences called by the French government followed in 1900, 1909, 1920, 1929 and 1938.

Illness was another matter. Farr had wanted the same nomenclature applied to diseases that disable without killing, and at the 1860 International Statistical Congress in London Florence Nightingale urged his classification for hospital statistics. No international morbidity list took hold, so countries wrote their own: Canada's Standard Morbidity Code of 1936, a U.S. Public Health Service list of 1940, and a British Medical Research Council classification for hospital admissions in 1944.

In 1945 the U.S. Department of State formed the U.S. Committee on Joint Causes of Death, chaired by Lowell J. Reed of Johns Hopkins University, to decide how to pick one cause when a certificate named several and to build a morbidity classification. The 1946 International Health Conference in New York gave the preparatory work to the Interim Commission of the World Health Organization. Its expert committee revised the American proposal and sent it to governments for comment as the International Classification of Diseases, Injuries, and Causes of Death.

The Sixth Revision Conference met in Paris from 26 to 30 April 1948 and adopted the classification. It approved an international form of medical certificate of cause of death and made the underlying cause of death, chosen by set rules, the main cause to be tabulated. On 24 July 1948 the First World Health Assembly adopted the revision together with WHO Regulations No. 1, to take effect on 1 January 1950. Earlier lists had been taken up or ignored as countries chose; the regulations bound member states with the force of a treaty unless they entered a reservation. The Manual came in two volumes, the second an alphabetical index of diagnoses. The Seventh Revision followed in 1955.