The Hummingbirds' Foundation for M.E.

The Hummingbirds' Foundation for M.E. (HFME) is fighting for the recognition of M.E.,
and for patients to be accorded the same basic human rights as those with similar
disabling and potentially fatal neurological diseases such as M.S.

The WHO and M.E. (in brief)

Myalgic Encephalomyelitis is a debilitating neurological disease which has been recognised by the World Health Organisation (WHO) since 1969 as a distinct organic neurological disorder. M.E. is classified in the current WHO International Classification of Diseases with the neurological code G.93.3.

The WHO and M.E.

The World Health Organization (WHO) classifies all known diseases in its International Classification of Diseases (ICD). The WHO states: 'The ICD is the international standard diagnostic classification for all general epidemiological, many health management purposes and clinical use.'

Myalgic Encephalomyelitis (M.E.) has been recognised and classified by the ICD since 1969 following the seminal work of Dr. Melvin Ramsay and others.  

The WHO recognises M.E.

ICD-10 classifies M.E. under Diseases of the nervous system. In other words, the WHO states that M.E. is a neurological disease

In the version of the ICD currently in use in most of the world except the US (ICD-10) M.E. is classified as a neurological disease. (ICD-10 is currently used in the UK, Australia, Europe, Canada and other countries. ICD-10 is the responsibility of the WHO, Geneva. ICD-10 CM (USA) will be used in future in the US.  Planned implementation is in 2013.)

In a world where the reality of M.E. is denigrated and denied by doctors, policy-makers and the general public, the ICD-10 classification of M.E. as a neurological disease is an important instance of the disease being given appropriate official recognition by the medical and scientific establishment.

M.E. is classified in the current WHO International Classification of Diseases with the neurological code G.93.3. As Professor Malcolm Hooper explains:

The term Myalgic Encephalomyelitis has been included by the World Health Organisation (WHO) in their International Classification of Diseases (ICD), since 1969. The current version ICD-10 lists M.E. under G.93.3 - neurological conditions. It cannot be emphasised too strongly that this recognition emerged from meticulous clinical observation and examination.

More information

To read or download an extended and fully referenced version of the above text, please see the The WHO ICD in relation to M.E. and 'CFS'  page.

Additional relevant links:

More information: The WHO and 'CFS' and 'ME/CFS'

A summary by Lesley Ben:
ICD-10 and 'CFS'

'CFS' is not classified in the Tabular list (the main body of the code listings) of ICD-10.  'CFS' is present in the Alphabetical index, published only in CD-ROM and book form, not online.  'CFS' has been listed in the index of ICD-10 since it was published in 1994.

'CFS' in the index is indexed to G93.3.  What does this mean? Clearly it indicates that 'CFS' has some relationship to the diseases at G93.3, i.e. PVFS and Benign ME, but what is this relationship?

ICD-10 does not say that 'CFS' is synonymous with M.E. ICD-10 is silent as to the relationship between CFS, and PVFS and ME.    

ICD-10 gives various possible relationships between a term in the Alphabetical index, and the term in the Tabular list to which it is indexed.  It may be:   

  • a synonym
  • 'a diagnostic term currently in use'
  • an 'imprecise and undesirable term' or 'a rubric for ill-defined conditions'  (all from Introduction to ICD-10 Vol.3, 2nd Edn.)
  • 'a best coding guess' (correspondence from the WHO).

However, ICD-10 does not specify which of these possible relationships applies in the case of 'CFS.'  Thus ICD-10 does not specify what relationship 'CFS' has with M.E.   

Nor has the WHO issued any statement which specifies the relationship between 'CFS' and M.E., despite requests for clarification.


ICD-10 and Combined Terms 'ME/CFS' and 'CFS/ME'

No version of the WHO ICD classifies the terms 'ME/CFS' or 'CFS/ME.' Nor do any past or currently planned future versions of the ICD classify either of these terms. Not only does the ICD not classify these terms, it does not mention them at all. 

Thus according to the ICD, 'ME/CFS' and 'CFS/ME' do not exist. The combined terms equate M.E. with 'CFS.'  This harms M.E. patients. 

M.E. and 'CFS' are not the same, so the combined terms are meaningless; they only increase confusion, which helps those who try to deny the medical reality of our disease, and give the impression that M.E. is 'mysterious.' 

The main problem with the term 'CFS' is that 'CFS' does not exist.  The definitions of 'CFS describe a heterogeneous group of patients suffering from a vast array of different diseases which cause fatigue.  The mixed-bag definitions of 'CFS' lend themselves to psychiatric interpretation, and yield meaningless research results. 

The term 'ME/CFS' does the same harm to the cause of M.E. as the term 'CFS/ME,' by equating M.E. with 'CFS.'   Equating the two, so M.E. patients are subsumed into the ill-defined morass of 'CFS,' is one of the most important strategies of those who deny the biomedical reality of M.E.

Neither combined term is justified by ICD-10.  The combined terms imply that 'CFS' and 'M.E.' are alternative names for the same disease, but ICD-10 does not say that 'CFS' is the same as M.E. 

'CFS' is in the index, indexed to the same code as PVFS and ME, but this does not mean it is synonymous with those diseases.  As discussed above, there are several possible relationships between a term in the index and the term at the code to which it's indexed.  Thus ICD-10 does not justify using the two terms as though they are synonyms.

The ICD does not recognise either 'ME/CFS' or 'CFS/ME.'   The absence of the combined terms from the ICD may be useful in our efforts to resist them.


US ICD versions, M.E., 'CFS' and Combined Terms


M.E. is hardly recognised in the US.  The disease formerly described as 'epidemic neuromyasthenia' in the US is now more likely to be diagnosed as 'CFS.' Unfortunately there is currently no classification for M.E. in the Tabular list of ICD-9 used in the US.  The closest to a classification of M.E. in ICD-9 is Unspecified cause of encephalitis, myelitis, and encephalomyelitis, which is in practice seldom used.  The lack of a listing for M.E. will be rectified in ICD-10 CM (USA) to be used in the US from 2013, which has a classification for M.E. as a neurological disease.


Unlike ICD-10, the US versions of the ICD are quite clear about the relationship between 'CFS' and M.E.: there is none.  Amy Blum, Medical Classification Specialist at the National Center for Health Statistics has stated:

'ME is not considered a synonymous term for chronic fatigue syndrome in the United States.'

Ms. Blum has also made the following illuminating statement:

' is not clinically valid to classify all cases of CFS to code G93.3.  The default will be R53.82 except in those cases where the cause is determined to be of viral origin.' 

(email to me,  9 July 2009)

'CFS' is coded in a completely different category from M.E. in the US.  ICD-9, currently used, does not classify M.E. as such, and the nearest equivalent is at 323.9 under Diseases of the nervous system and sense organs while 'CFS' is at 780.71 under Symptoms, signs, and ill-defined conditions.

ICD-10 CM (USA), for use in future, classifies M.E. at G93.3 under Diseases of the nervous system, while 'CFS' is at R53.82 under Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.

Combined terms 'ME/CFS' and 'CFS/ME'

The combined terms are not supported by ICD-10; still less are they supported by the US ICD versions.  As discussed above, M.E. and 'CFS' are at completely different codes within different categories.  Thus the combined terms, which equate 'CFS' with M.E., are not supported by the US ICD versions. 


Recommendations for Future

  • The classification for M.E. should remain at G93.3 Myalgic Encephalomyelitis under Diseases of the nervous system.

  • The name currently given first at G93.3 in ICD-10 and ICD-10 CM (USA), 'Postviral fatigue syndrome,' should be removed.  It is not correct: M.E. is not a syndrome.  Fatigue is not a defining symptom of M.E.; it is frequently but not necessarily present, and when present it may be only a minor symptom. Fatigue following viral infection is not a neurological disease and should be classified elsewhere as appropriate.

  • The current term 'Benign' should be deleted from before 'Myalgic encephalomyelitis.'  It is not correct.  The term 'benign' (meaning 'not fatal') was originally introduced in the context of the WHO's efforts to categorise epidemic diseases, and indicated that a disease did not kill more than a certain percentage of its victims.  However, this usage is not consistent throughout the ICD.  The term misleadingly obscures the fact that M.E. can be fatal.The term also contributes to the public misunderstanding of M.E.  Some people interpret 'benign' to mean that M.E. is not a serious illness.  This is unfortunate considering the degree of severe disability and suffering which may be experienced by M.E. patients. 

  • There should be no ICD listing for 'CFS' as a valid disease term.  'CFS' does not exist and should not be given the status of a real disease. However, many patients are diagnosed with 'CFS' and need the protection of an ICD listing. 
         'CFS' could be classified in the ICD within a new category containing invalid disease terms.  This would acknowledge that while patients are in practice diagnosed with the term, it is not valid. 
         The ICD-10 already accepts that patients are in practice diagnosed with 'imprecise and undesirable term[s]' for 'ill-defined conditions,' in that such terms are given in the index. A category of invalid disease terms would make explicit what is already implicit in categories such as 'Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified': not that the disease is not real, but that the patient requires a better diagnosis.

  • Failing the proposal above or similar, 'CFS' should not be classified in the ICD. The false disease category of 'CFS' does not serve the best interests of patients.  All patients would be better off with an accurate classification of a real disease, whether they suffer from M.E. or from another condition.  Accurate classification would facilitate not only insurance and welfare claims, but also appropriate treatment.  
         ICD classification of 'CFS' as a valid disease is not the way forward; it harms M.E. patients as well as those suffering from undiagnosed conditions who have been falsely classified with 'CFS.'

  • The fault in the online search facility for ICD-10 should be corrected so that the default 'full search option' which is supposed to include a search of the index, should indeed find terms in the index. 

  • All rather than only part of the WHO ICD should be published on the WHO website.  The WHO should publish the Alphabetical index of the current ICD-10 online.  If this is impossible for some reason, the WHO website should call attention to its omission.  All of the future ICD-11 should be published online.   If the WHO ICD is truly to serve its worldwide constituency, it must be available online in its entirety.



Please see Lesley Ben's full length paper for references, including official and alternative online listings of the ICD codes.