Redefining an Illness
By Suzanne D Vernon, Ph. D, SMCI Scientific Director
On February 10, 2015 the Institute of Medicine (IOM) issued the long awaited report on diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) titled, “Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness”. This 304-page landmark report is remarkably thoughtful, highly informative and an accessible evidence-based document that succeeded in providing medical providers a much-needed framework for diagnosing ME/CFS (SEID).
In the weeks ahead, I will break down the report allowing a better understanding as to why the committee recommended these particular diagnostic criteria. There has been much discussion on the diagnostic criteria put forth in the IOM report, and debate on how this may affect clinical practice and research. It is important to begin with clarifying what is meant by “case definition” and “clinical diagnostic criteria”:
- Case definitions are used in research to identify biomarkers and causes of diseases. A case definition is an epidemiological tool used to establish whether a patient can be linked to an outbreak and to determine the number of people in the affected population – or “cases” involved in an outbreak. (Epidemiology is the science that studies the patterns, causes, and effects of health and disease conditions in a specifics population.) It is not recommended that case definitions be used to guide clinical practice. Case definitions should be designed to be simple and practical and are formulated to include the following components:
- Time – a period of time “cases” are associated with an outbreak
- Place – limiting “cases” to a geographical location
- Person – personal characteristics (e.g., age, sex) as well as clinical and laboratory criteria that are hallmarks for the illness
- Diagnostic Criteria are used by medical providers to help diagnose what is making an individual sick. People often present to their doctor with symptoms like pain and fatigue that are nonspecific. Many medically unexplained diseases do not have objective diagnostic tests making diagnosis challenging. Medical providers use many of the following types of information to make a diagnosis:
- Intake history (the events that preceded the visit to the doctor)
- Medical history
- Family history
- Physical examination
- Diagnostic tests (e.g., blood tests, imaging procedures, etc.)
Perhaps the biggest difference is that “case definition” deals with populations of patients and “diagnostic criteria” focuses on the individual.
There are currently no diagnostic laboratory abnormalities or clinical tests that can be used to diagnose ME/CFS. The IOM committee was charged with developing evidence-based clinical diagnostic criteria for ME/CFS. In other words, what could the IOM committee recommend with confidence that medical providers could use to diagnose ME/CFS in an individual who comes into their office. The IOM committee did not limit themselves to the peer-review medical literature and in fact drew upon the extensive input from the patient community and also reviewed and evaluated unpublished data. The committee developed a process or diagnostic algorithm that providers could use to make an ME/CFS diagnosis.
Many case definitions put forward, such as the Canadian Consensus Criteria and Fukuda, have been a combination of research and diagnostic and have not been operationalized for a clinical setting. This has led to much confusion and a lack of adoption. We believe that the diagnostic criteria recommendations from the IOM are an important step in moving ME/CFS into the medical mainstream. It is clear that the IOM considered the Canadian Consensus Criteria in coming up with these evidence-base diagnostic criteria. It was also clear that the IOM wanted criteria that could be more readily and easily used by physicians.
Another important aspect of the IOM report is that it declared that ME/CFS/SEID must no longer be a diagnosis of exclusion. Patients can and must be diagnosed so that they can begin to receive the care that they need. This simple criteria will help move diagnosis and treatment forward. This flow diagram is the streamlined and systematic approach using specific diagnostic criteria that was recommended by the IOM committee:
This disease has been poorly defined, which means that diagnosis is difficult. That is not uncommon for a multisystem, complex disease, with symptoms that appear in other illnesses as well, and can be difficult to measure objectively. There is no simple blood test, or genetic test for diagnosis. The newly discovered biomarkers are few and cannot be done routinely in a doctor’s office. And as it is a genuinely complex disease and therefore can be difficult to diagnose. Doctors face an overwhelming amount of information to absorb, 15 minute appointment slots in their days, filled with both time and financial pressures. With new, clear diagnostic criteria as put forth, diagnosis is far less complicated and more readily deployed in the clinical setting. A simpler criteria, well deployed and utilized, will lead to better, faster diagnosis for millions of suffering individuals.
This represents the federal government clearly affirming that this is a serious, physical disease, not a syndrome. For the million Americans who have long suffered with skepticism and lack of care, this is deeply affirming.
Access the full clinicians guide HERE
This is but one piece of a very lengthy and thorough report. In the weeks ahead, we will put forth a series of blog posts, focused on a deeper dive into the evidence for each of the diagnostic criteria, one by one. The final post in this series will discuss how the scientific community can use these clinical diagnostic criteria to advance ME/CFS research.
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