ICD stands for the International Classification of Diseases and is produced by the World Health Organization. It is used to track the mortality and morbidity of diseases globally. WHO has recently released ICD-11 but most countries are using ICD-10, published in 1990 and will likely do so for a number of years.

Countries are allowed to produce their own clinical modifications as long as they follow WHO standards. The US version of the ICD-10 is the ICD-10-CM, released in 2015. The ICD-10-CM is used in electronic health records to code the diagnoses provided by doctors.

The ICD-10-CM is used in the US. This does not change the ICD-10 used in other countries.

The term “ME/CFS” does not exist in the ICD-10 or ICD-10-CM, even though the US federal agencies and numerous medical education providers have adopted the term. The only terms that exist are “ME” and “CFS.”

The WHO classifies ME and CFS in the neurological chapter of both ICD-10 and ICD-11 as inclusion terms (essentially synonyms) of the lead term “postviral fatigue syndrome (PVFS).” The US also classifies ME in the neurological chapter of ICD-10-CM under PVFS. However, when the ICD-10-CM was rolled out in the US in 2015, the US relocated CFS to the Symptoms chapter and gave it the same code as the symptom of “chronic fatigue, unspecified.”

NOTE:
A) “benign” was dropped from ICD-10 in 2019. The organizations requested it be dropped in the ICD-10-CM as well.
B) In ICD-10, ME and CFS are “inclusion” terms of postviral fatigue syndrome and have the same code. In ICD-10-CM, benign ME is an inclusion of Postviral fatigue syndrome and CFS is an inclusion of chronic fatigue, unspecified for each, use the same code as the lead term.
C) “Exclusion” coding rules do not allow for both CFS and ME to be diagnosed at the same time.

The National Center for Health Statistics (NCHS, the CDC group that manages ICD-10-CM) has stated the intent behind separating ME and CFS in this way was that ME would be used if proven viral etiology and CFS for all other cases. The US is the only country in the world to have done this and it is not aligned with either ICD-10 or ICD-11.

Attendees at a previous meeting on ICD-10-CM held by the NCHS stated that ME is seldom seen in medical records. The vast majority of US doctors use the term “CFS.” And if a doctor were to record a diagnosis of ME/CFS, the person assigning the code in the medical record would have to choose either the code for CFS or for ME since there is no code for ME/CFS and the two codes cannot be used at the same time. As a result, the vast majority of Americans diagnosed with ME/CFS in the US will end up with the code for the symptom of “chronic fatigue, unspecified” in their medical records instead.

This makes it impossible to track and report on the mortality and morbidity of cases of ME/CFS separate from the symptom of non-specific chronic fatigue due to any cause. This likely impedes insurance reimbursement, generation of statistics on disease burden and outcomes, the medical perception of ME/CFS. And it also makes it virtually impossible to identify ME/CFS cases in retrospective research using electronic health records, such as that being done for Long COVID. Notably, at the 2021 IACFS/ME conference, CDC reported that it was unable to identify ME/CFS cases in electronic records using just the ICD code. They had to do a manual chart review which is expensive and time consuming.

Before the pandemic, this affected an estimated 1 to 2.5 million Americans with ME/CFS, leaving them effectively lost in the medical system. This only affects US patients as the ICD-10-CM is the version of ICD-10 used in the US.

These numbers are expected to grow significantly, given the risk of people developing ME/CFS following an acute COVID-19 infection. While no firm estimates exist, previous studies suggest that as many as 10-12% of people can develop ME/CFS following an infection. This could translate to millions of new cases of ME/CFS. Some Long COVID patients, those experiencing prolonged symptoms post-COVID, have already been diagnosed with ME/CFS. And emerging clinical care guidance for Long COVID is already recognizing the potential link.

Proposals were submitted to NCHS in 2011, 2012 and again in 2018 to move CFS back to the neurological chapter. But these proposals were rejected because of lack of stakeholder consensus on how to resolve this problem. Stakeholders to the NCHS process include groups such as the medical community, the patient community, and hospital and coding associations.

Examples of areas of lack of consensus included:

• Whether or not CFS should be moved back to the neurological chapter at all since it has been used as a wastebin diagnosis and/or because it has not been proven to be specifically neurological.
  • Note that WHO has said terms should not be moved from one place to another unless robust science supports that decision. This is in part why ME and CFS remain in the neurological chapter in ICD-11, since it was located there originally in ICD-10 and not enough research has been done to justify its reclassification.
• Whether CFS and ME are the same thing and should have the same code or are different and should have different codes.
• Whether doctors will be confused if CFS and ME have different codes.
• Whether CFS belongs under postviral fatigue syndrome since it is not always postviral
• Whether SEID should be added since the term was not adopted.
  • This was discussed in the 2018 meeting and in comments submitted after. The main point raised by the community was that this term has not been adopted in the US and should not be added. But NCHS said if the term is used in medical records, there needs to be a code for it.

Seven organizations including The International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis, #MEAction, Open Medicine Foundation, Solve M.E., Massachusetts ME/CFS & FM Association, Minnesota ME/CFS Alliance, and Pandora Org submitted a proposal to NCHS asking for three primary changes to the ICD-10-CM:

• Expand the lead term for G93.3 from “post-viral fatigue syndrome” to “postviral and related fatigue syndromes”, to accommodate non-viral triggers (Note that WHO rules require that the words in the current title, “postviral fatigue syndrome,” are also in the new title. Options for this lead term are limited.)
• Remove “benign” from the term “myalgic encephalomyelitis”
• Provide separate subcodes (G93.3n) for post-viral fatigue syndrome and myalgic encephalomyelitis since ME is not always postviral (Per ICD convention, we also included a subcode for “other” conditions not included in these.)
• Add the terms “myalgic encephalomyelitis/chronic fatigue syndrome” and “ME/CFS” as inclusions (essentially a synonym) of myalgic encephalomyelitis. (The term ME/CFS has been adopted by US government agencies and clinical guidance providers.)
• Revise existing exclusion codes as needed to reflect these changes and add an exclusion for neurasthenia. (In this case, an exclusion prevents ME/CFS and neurasthenia from being diagnosed at the same time.)

These changes would be coded in ICD-10-CM as follows:
        Diseases of the nervous system
        G93 Other Disorders of the brain
             G93.3 Postviral and related fatigue syndromes
                  G93.3x    Postviral fatigue syndrome (one subcode of G93.3)
                  G93.3y    Myalgic encephalomyelitis (a second subcode of G93.3)  
                                  Myalgic encephalomyelitis/chronic fatigue syndrome
                                  ME/CFS
           G93.39    Other postinfection and related fatigue syndromes

The submitted proposal focused on getting the term ME/CFS added as doctors are using that term and it needs to be in the ICD-10-CM. It did not ask to have the term “chronic fatigue syndrome” moved back to the neurological chapter because stakeholders had rejected various options for doing this in the last three proposals.

Some have asked whether WHO rules allow the term “ME/CFS” to be added as a conjoined term because the separate terms ME and CFS already exist as unique terms. But as WHO documentation notes, "ICD is used to translate diagnoses of diseases other health problems from words into an alphanumeric code." If WHO is to serve its role of tracking diseases as described and named in clinical practice, the term need to be added.

When NCHS receives proposals, it sometimes add recommendations for additional or different coding changes. For the proposal for ME/CFS, NCHS has recommended these additional coding changes:

• Make the lead for one of the G93.3n subcodes “myalgic encephalomyelitis/chronic fatigue syndrome” and include the terms “myalgic encephalomyelitis,” “chronic fatigue syndrome,” and “ME/CFS” as inclusions of that lead term. All will have the same code
• The term ”chronic fatigue syndrome” is being moved back to the neurological chapter. The World Health Organization and other countries classify CFS in the neurological chapter at G93.3.
• Add the term ‘systemic exertion intolerance disease” to the index file using the subcode for ME/CFS. The index file is essentially a secondary index of diseases. (In the 2018 meeting, NCHS said this addition was required if US doctors were diagnosing SEID.)
• Revise the terms Akureyri's disease, Iceland disease, and Neuromyasthenia in the index file to point to a new subcode, “Other post infection and related fatigue syndromes.” (These terms are historical terms for the disease that is today called ME or ME/CFS. As such, the index code for these terms should be the same as that for ME.)

 These changes would be coded in ICD-10-CM as follows:
    G93 Other disorders of brain
    G93.3 Postviral and related fatigue syndromes
              Benign myalgic encephalomyelitis
         G93.31 Postviral fatigue syndrome
         G93.32 Myalgic encephalomyelitis/chronic fatigue syndrome
             Chronic fatigue syndrome
             ME/CFS
             Myalgic encephalomyelitis
         G93.39 Other post infection and related fatigue syndromes

    R53 Malaise and fatigue
         R53.8  Other malaise and fatigue
              R53.82 Chronic fatigue, unspecified
                      Chronic fatigue syndrome NOS

    Primary additions and revisions to the Index file
         Systemic exertion intolerance disease [SEID] G93.32
         Akureyri's disease G93.39
         Iceland G93.39
         Neuromyasthenia (epidemic) (postinfectious) G93.39

Some of the additional changes proposed by NCHS were previously rejected because of lack of agreement, including by the patient community, on whether and/or how the change should be made.

We recognize that you may not agree with some or all of the changes proposed by NCHS. If so and you provide comments during the public comment period, please be specific about which coding changes you support and to which you object. In order for US ME/CFS patients to be counted and tracked, it's important that at least the changes proposed by the seven organizations are approved so people with ME/CFS can be tracked.

No, this does not fully address the problem.

The proposal submitted by the organizations did not address how CFS is classified in the US ICD-10-CM. ME/CFS patients who currently have a CFS diagnosis would have to be rediagnosed with ME/CFS to have the ICD code added to their medical record.

NCHS’ recommended proposal did address the classification of CFS so if this change was implemented, future medical records with a diagnosis of CFS would no longer be equated to “chronic fatigue, unspecified.”

But in both cases, this would not automatically change all the historical records where the CFS term was used. These historical CFS records would continue to be subsumed under the symptom of “chronic fatigue, unspecified” in medical records and cannot be separated out by codes alone.

This proposal is scheduled to be discussed at the ICD-10-CM Coordination and Maintenance Committee meeting on September 14-15, 2021. After the meeting, there will be an opportunity for public comment prior to a final decision by NCHS. If the proposal is accepted, the change would be implemented in October 2022.

It could. Some people with Long COVID may develop and be diagnosed with ME/CFS. This will ensure they are correctly tracked and not dumped into the “chronic fatigue, unspecified” bucket.

It is difficult to get disability for ME/CFS in the US. But this change should not impact that. The 2014 Social Security Administration (SSA) ruling for this disease used the term “CFS” but referenced the 2003 ME/CFS Canadian Consensus Criteria and the 2011 ME International Consensus Criteria. Since then, SSA has published the 2018 guide for healthcare professionals that refers to the disease as Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.