How the International Classification of Diseases coding system got its start and why emergency physicians should know its diagnostic terminology

ICD-9-CM and its related documentation have been around since 1979. It is the only subject that applies to every patient encounter, but the prevailing dogma in US medical schools, where this topic should be taught, is that the students “don’t need it.”

If I am successful educating emergency physicians, at least four physicians at every hospital in the nation will “get it.” But, I must admit, I will seriously miss the most satisfying part of face-to-face teaching, that of watching the sudden change in expression that accompanies the transition from unawareness to understanding as physicians realize why their diagnostic terminology is so important.

In order to appreciate ICD-10-CM, it is necessary to have a working knowledge of the system in which it plays such a crucial part. Unfortunately, every non-physician hospital administrator, office staff, and billing-service personnel functions under the misconception that medical-school curricula include Medical Finances 101. Non-physicians are incredulous when I explain that the 28,000 pages of medicine learned in four years of medical school do not include a single page of Current Procedural Training, ICD-9-CM, or the 110,000 pages of Centers for Medicare & Medicaid Services (CMS) regulations that physicians are supposed to master before seeing their first Medicare patient. Most people do not believe that the most common question I am asked by doctors is, “What is ICD-9?”

To those who know the history of ICD-9, please accept my apologies for this crash course. It’s for the majority of physicians who have never had the pleasure of learning it.

ICD-9 is the ninth version of the International Classification of Diseases (ICD) published by the World Health Organization (WHO) in 1977. This ICD dates back to a systematic classification of diseases causing death, the Nosologia methodica, created in the 1700s by French physician François Bossier de Lacroix Sauvages to track epidemics and pandemics.

In the intervening 300 years, classification of death diseases enjoyed a continuous stream of proponents and “experts” who improved on the structure, nomenclature, and standardization of the system, sometimes creating competing classifications, sometimes combining their ideas. First cities, then states and nations adopted classifications to describe and track the cause of death within their borders.

In 1853, in recognition of the need for a uniform classification, the First International Statistical Congress asked William Farr of Scotland and Marc d’Espine of Geneva to prepare an internationally applicable, uniform classification of causes of death. Neither of the two classifications was ever universally accepted, and in 1893, the International Statistical Institute adopted the Bertillon Classification of Causes of Death developed by Jacques Bertillon, chief of statistical services of Paris. The classification, a distillation of English, German, and Swiss classifications, was based on Farr’s principle of distinguishing between general diseases and those localized to a particular organ or anatomical site.