Although neither the Fourth nor Fifth Revision contained many changes, the Fifth International Revision Conference did recognize the increasing need for a list of diseases to meet the statistical requirements of widely differing organizations. The conference recommended a second joint committee of the two organizations to prepare an international list of diseases.

In 1944 (the year I came on the scene just to give you some perspective), the United Kingdom and the U.S. published their own classifications of diseases and injuries for tabulation of morbidity statistics. More extensive than the Canadian list, both lists followed the general order of diseases in the International List of Causes of Death.

The 1946 International Health Conference entrusted the Interim Commission of the World Health Organization with the responsibility of the Sixth Revision and with the establishment of International Lists of Causes of Morbidity. Taking into account prevailing opinion concerning morbidity and mortality classification, WHO revised the classification prepared by the United States, combined it with the revised International Lists of Causes of Death, and published the resulting classification as the Sixth Revision of the International Classification of Diseases, Injuries, and Causes of Death.

In 1948 (the year I made my first diagnosis, “pendicitis,” and declared to my family that I would become a doctor), the First World Health Assembly adopted the WHO International Form of Medical Certificate of Cause of Death and the special lists for tabulation of morbidity and mortality data. This Sixth Revision, shortened to the International Classification of Diseases (ICD-6), heralded a new era in international vital and health statistics. The conference approved a comprehensive list for both mortality and morbidity, agreed on international rules for selecting the underlying cause of death, recommended a comprehensive program of international cooperation in the field of vital and health statistics, and suggested that governments establish national committees on vital and health statistics to coordinate statistical activities and serve as a link between the national statistical institutions and WHO to study statistical problems of public-health importance.

ICD Revisions Seven (1955) and Eight (1965) (during which time I was busy applying to medical school) made only limited, essential changes and amendments to correct errors and inconsistencies in the ICD. During these years, many countries made national adaptations to the ICD to provide additional detail for indexing hospital medical records.

Then, in 1975 (my second year in EM practice), the WHO International Conference for the Ninth Revision of ICD determined that areas of the classification were inappropriately arranged, more detail was needed, and it should be redesigned to be used for evaluating medical care. The conference retained the basic structure of the ICD; added significant detail; and incorporated an alternative method of classifying diagnostic statements, including information about both the etiology (marked with a “dagger” [+]) and manifestations (marked with an “asterisk” [*]) of a disease, which is the system used in ICD-10. ICD-9 innovations were included to increase its flexibility, coding rules were amended, and rules for the selection of a single cause of morbidity were introduced.