Nosology is the part of medicine that studies the criteria used to define diseases in order to establish a classification. It is used in the identification of causes of death and the digitization and coding of medical records.

Nosology is the part of medicine that studies the criteria used to define diseases. Its objective is to describe and study diseases in order to establish a classification. It is a discipline that gives practitioners a conceptual framework to help them orient themselves in the midst of all the entities (symptoms, side effects) that characterize or result from a disease.

Also called coder expert, the nosologist is not a specialist consulted directly by patients. They work for specialized medical centers or hospitals. 

Since the 19th century, practical and Public Health objectives have been associated with nosology. These goals have led to the creation of coding systems such as:

• The International Classification of Diseases (ICD): it serves as the basis for establishing health trends and statistics, around the world, and contains approximately 55 unique codes for injuries, diseases and causes of death. It provides a common language through which health professionals can exchange health information anywhere in the world;
• The Common Classification of Medical Acts (CCAM): it has been used since January 1, 2004 and is used both to describe the activity carried out and to bill the activity of city practitioners, for which it is gradually replacing the General nomenclature of professional acts (NGAP).

Identification of causes of death

Specialized centers, such as the Center for Epidemiology on Medical Causes of Death (CépiDc) at Inserm, are responsible for:

• Produce national mortality data by cause;
• Carry out studies on the quality of these data;
• Conduct epidemiological research on death statistics.

In this context, the role of nosologists is to deal with complex cases of medical coding. The experts check the CIM codes assigned to the different nosological entities present on the death certificate, and they choose the initial cause of death by applying the CIM rules and the coding guidelines in force.

Digitization and coding of medical records

Nosologists are responsible for digitizing medical records and coding them using current medical classifications. This coding makes it possible in particular to classify hospitalizations and to invoice them.

To become a nosologist, you need a Bac + 2 with preferably a specialization in the field of health, documentation or classification.

In terms of know-how, a good command of computer software (office automation, coding) and a good level of English are required. Medical knowledge, in particular of the different coding systems, is required.