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.

In 1898, the American Public Health Association recommended the adoption of the Bertillon Classification by registrars of Canada, Mexico, and the U.S. and that it be revised every 10 years. In 1899, the International Statistical Institute recommended the adoption of the system of nomenclature by all the statistical institutions of Europe. And, in 1900, this detailed classification of causes of death was adopted, with Bertillon as the guiding force promoting and supervising revisions of the International List of Causes of Death every 10 years until his death in 1922.

Parallel to the continued evolution of the International List of Causes of Death, a similar list of diseases dates back to Farr, who also recognized that it was desirable “to extend the same system of nomenclature to diseases which, though not fatal, cause disability in the population.” Even Florence Nightingale, in 1860, urged the adoption of Farr’s classification of diseases for the tabulation of hospital morbidity, but it wasn’t until 1900 that a classification of diseases for statistics of sickness was adopted.

The categories for nonfatal diseases were formed by subdivision of certain rubrics of the cause-of-death classification. Because this international classification of illnesses was a limited expansion of the causes of death, it failed to gain international acceptance. Absent a uniform classification of diseases of illness, many countries prepared their own lists. An English translation of the Second Decennial Revision of the International List of Causes of Death entitled International Classification of Causes of Sickness and Death was published by the US Department of Commerce and Labor in 1910.

In 1928, the Health Organization of the League of Nations Commission of Statistical Experts studied both the classification of diseases and the causes of death. Participant E. Roesle, chief of the Medical Statistical Service of the German Health Bureau, expanded the rubrics of the 1920 International List of Causes of Death and detailed what would be required if the classification was to be used for morbidity as well as mortality statistics. To coordinate the work of the International Statistical Institute and the Health Organization of the League of Nations, an international commission was formed with representatives from both organizations. This commission drafted proposals for the Fourth (1929) and the Fifth (1938) Revisions of the International List of Causes of Death.

In 1936, the Dominion Council of Health of Canada published a Standard Morbidity Code with 18 chapters of the 1929 Revision of the International List of Causes of Death subdivided into 380 specific disease categories. A modification of this list was introduced at the Fifth International Conference in 1938 as the basis for an international list of causes of illness, but no action was taken.

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.

However, prior to the Ninth Revision Conference, WHO was preparing for the 10th Revision. Increasing uses of ICD highlighted the need for a stable and flexible structure to eliminate frequent revision. The WHO Collaborating Centres for Classification of Diseases experimented with alternative structures for ICD-10 and determined that the 10-year interval between revisions was too short to evaluate current use and identify needed revisions. So the 10th Revision Conference, scheduled for 1985, was delayed.

Beginning in October 2014, the migration must be completed, as ICD-9 fades to black and ICD-10 will be the required system to code and bill a chart. In the upcoming months, I’ll provide practical updates, making certain every emergency physician has a strong foundation for practicing in this new era.

Dr. Bensen is president of Medical Education Programs in Buffalo Junction, Va. She is an AHIMA approved ICD-10-CM/PCS Trainer, a senior medical associate at MedAcess in Roxbo, N.C., and Councillor for VACEP. She is a former member of the ACEP Board of Directors.

References

1. www.who.int/classifications/icd/en/HistoryOfICD.pdf
2. www.cdc.gov/nchs/icd/icd9.htm
3. www.ncbi.nlm.nih.gov/pmc/articles/PMC2916773/
4. www.meditec.com/resourcestools/icd-codes/
5. www.cms.gov/Medicare/Medicare-Contracting/ContractorLearningResources/downloads/ICD-10_Overview_Presentation.pdf