27. oktober 2004 

Codes, Names & Definitions, a Brief Guide.
Jean Harrison
MAME inc.


Codes

In 1900 the World Health Organization decided to attach numbers to 
disease names creating what they called the International 
Classification of Diseases, or ICD. These numbers are referred to as 
'codes'.  The ICD was updated about every ten years; each time it was 
updated it’s version number was increased.  The first is referred to as 
ICD revision 1; the most recent, ICD revision 10 or just ICD-10 for 
short. If a given disease is named or discovered between editions often 
times it’s not included till the next revision.

  Each country is allowed to make changes to the ICD with the WHO’s 
permission; the changed edition is marked 'CM' meaning clinical 
modification.  Over the years the ICD has grown and grown, from what 
must have been a slim volume to now three separate volumes.  In 1992 a 
was change made, that is the addition of letters to the numbers. Thus 
the ICD-10 (version 10) is alphanumeric. The letters of the alphabet 
represent different categories; a disease listed under an 'F' is a 
psychiatric disorder, a disease listed under 'G' is a neurological 
disorder.

Example: A code from the previous version (ICD-9) might read 323.9 or 
780.71; codes from the ICD-10 could be F48 or G93.3.

  The ICD is used for different things by different countries, the US 
relies upon it heavily for insurance billing purposes. If you have 
insurance whose reimbursement is based upon whether or not the illness 
you have is psychiatric or not, the codes can become quite important. 
As the US uses the codes so often, sometimes new diseases, or renamed 
diseases are put in different editions of our ICD CM.  Also important 
for understanding the codes is that there is an index to the 
classification section. Sometimes disease names are listed only in the 
index, but given the code of a disorder listed in the main section of 
the ICD.

The US is gradually phasing in the ICD-10, which was first published in 
1992. The name chronic fatigue syndrome was created in 1988 and appears 
in the index of the ICD-10 under code G93.3. Other disease names listed 
to that code are myalgic encephalomyelitis & post viral fatigue 
syndrome.

  In 1998, the US decided to add CFS to it’s ICD-9CM. It was added as 
code 780.71, under a section called 'Symptoms, Signs and Ill Defined 
Conditions, Fatiguing Illnesses'. ME is in the ICD-9 also, under 323.9, 
in the neurological section.

Names:

CFS was not a new illness, it was just a rediscovered one. Arguably 
dating from early history, the description of the illness can certainly 
be traced to the 1930’s when there was an outbreak in the LA County 
Hospital. At that time it was thought to be a form of atypical or 
non-paralytic polio. Over the years many other outbreaks which fit the 
major characteristics of the illness were discovered, rediscovered, and 
usually given a different name, often after the place in which the 
outbreak occurred. In 1955 a seminal outbreak occurred in London at the 
Royal Free Hospital & in keeping was called The Royal Free Disease. 
However in 1956, it was suggested in a British medical journal that the 
disease be called 'benign myalgic encephalomyelitis' It was thus 
entered in the ICD-8 of 1965. The ICD-7 had come out in 1955. 'Myalgic 
encephalomyelitis' (meaning pain, and inflammation of the brain and 
spinal cord) went into widespread use, though the US termed the illness 
'epidemic neuromyesthenia'.  Note: it’s not all that unusual for the US 
to call a given disease a different name; what is called Arterial 
Lateral Sclerosis (ALS) here is called 'motor neuron' disease in the 
UK; mononucleosis is called 'glandular fever' in the UK.

Definitions:

Until a disease has a known cause it’s separated from others by a 
definition. Diabetes for example, has just been redefined, rheumatoid 
arthritis has been defined repeatedly. What is perhaps unusual about 
CFS or ME/CFS is that there are several conflicting definitions in 
current use.

In 1988 the first use of the term chronic fatigue syndrome was applied 
to a definition which experts in epidemic neuromyesthenia and myalgic 
encephalomyelitis refused to sign their names to. CFS was the name 
which replaced 'Epstein Barr Syndrome' which fell out of favor when it 
was determined that the Epstein Barr virus did not cause the disease.

The most commonly used definition of CFS was developed in 1994 by a 
consensus committee at the CDC. Known variously as CDC’94 or Fukuda ‘94 
it was created by two different camps of doctors, one camp thought that 
the disease was physiological, the other that it was psychiatric. The 
result was predictable, a definition which pleases very few, if anyone, 
and a definition which was very broad. The result has been that the 
patient population which fits the ‘94 definition is heterogeneous - so 
much so that with the increased specificity of some tests, people have 
been rediagnosed.

In the last few years a new definition, the Canadian Clinical Criteria 
was created in the hopes of paring things down. Naturally it’s 
difficult to impossible to find a common thread, a cause or a marker, 
for a very broadly defined illness. The result is that research into 
the illness is that much more difficult, and treatment is that much 
harder to find. Treatments which benefit some harm others.

Many of those who find that their symptom pattern closely resembles 
that of the Royal Free Disease, prefer to use the name myalgic 
encephalomyelitis. They prefer to use the code 323.9, which is still 
listed in the ICD-9. Others believe that because the name myalgic 
encephalomyelitis hasn’t been proven to be accurate it should not be 
used.