DIAGNOSIS OF CFS
Given the complexity of CFS, how can
primary health care physicians diagnose the presence of chronic fatigue with a
greater degree of confidence? In the development phase of this curriculum,
clinicians Drs. Nancy Klimas and Charles Lapp took the CFS case definition and
created a decision-making
model to guide clinical assessment of patients with CFS-like
symptoms. This model provides a step-wise approach to making a sound clinical
Patients who present with fatiguing
illnesses must be carefully evaluated clinically. The diagnosis of CFS is
primarily one of exclusion and can only be made after such evaluation. Clinical
evaluation of persons with a fatiguing illness requires: 1) a detailed patient
history, including review of medications that could case fatigue, 2) a thorough
physical examination, 3) a mental status examination and 4) a minimum battery of
laboratory screening tests. Lab tests should include:
-Complete blood count with leukocyte
-Erythrocyte sedimentation rate or C
aminotransferase or aspartate transaminase serum level
function test (TSH and Free T4)
-Rheumatoid factor (if arthritic complaints are
Routinely doing other laboratory
tests for all patients with chronically fatiguing illnesses has limited value.
However, further tests may be indicated to confirm or exclude another diagnosis,
which better explains the fatigue state (e.g., polysomnography for a patient
with suspected sleep apnea).
A complete history and physical
will take more than the standard 15-30 minute office visit. Realistically,
providers should expect the first visit to take close to an hour. Recognizing
your time limitations, written assessment tools can be given to the patient to
fill out ahead of time or between visits.
If no other
plausible explanations are found for the fatiguing illness, then assess the
patient to see if they meet four or more of the eight symptom criteria. If less
than four of the criteria are met, then the patient should be diagnosed with
non-syndromic chronic fatigue. However, the primary health care provider should
exercise judgment here, based on the course of illness, other symptomology and
the patientís medical history.
Although CFS requires fatigue of at
least six months duration, initial evaluation of patients with fatigue should
not focus on fatigue as a distinct entity. Rather, the entire presenting symptom
complex must be evaluated. If the patient has had symptoms of chronic fatigue
for less than six months, then he/she needs to be re-evaluated depending on the
results of the physical evaluation. Crucial to clinical care of patients with
CFS and other unexplained fatiguing illnesses is continued interest and
evaluation by the health care provider.
If the fatigue is chronic/relapsing
for six or more consecutive months and is unrelieved by bedrest, then determine
if the fatigue has significantly affected the patientís lifestyle, ability to
work or attend school. A version of the
Fatigue Impact Scale is
a helpful and valid measure of the functional impact of fatigue. When combined
with data from the patientís history, this one-page self-administered tool
provides valuable diagnostic information and can also be important in
If the patient has had more than 6 months
of fatigue and indicates that it has not had a major effect on his/her lifestyle
or work then non-syndromic chronic fatigue is the diagnosis of choice.
Conservative treatment with periodic follow-up is appropriate.
During the medical history, plausible
explanations for symptoms must be explored. A variety of medical conditions can
explain CFS symptoms and must be ruled out. Such conditions include:
|-Latrogenic, e.g., medication side
|-Active alcohol or substance abuse*
|-Chronic active hepatitis B or C
||-Major depressive disorder |
|-Nutritional deficiency, e.g., fad diets or
*Active is defined as alcohol or
drug/substance use currently and/or within the preceding two years.
To illustrate, we know that fatigue
accompanied by fever, malaise and weight loss suggest an inflammatory or
infective process, and fatigue with weight gain and cold intolerance may
indicate hypothyroidism. Furthermore, commonly prescribed medications (e.g.,
antihistamines, sedatives) and other substances (e.g., amphetamines, marijuana
and alcohol) can cause fatigue.
The physical exam should also focus on
ruling out alternative diagnoses. Persons with CFS often have a relatively
normal physical exam. The presence of severe objective muscle weakness,
neurological signs or cardio-respiratory disease might indicate other
conditions. While persons with CFS often report cervical and axillary lymph node
tenderness, lymphadenopathy is rarely present.
Major depression is the most common
alternative diagnosis to evaluate in adults who present with fatiguing symptoms.
A diagnosis of CFS cannot be made without appropriate psychological evaluation.
Depending on the primary health care providerís expertise and confidence in
conducting a psychological evaluation, a consultation with a specialist (i.e.,
psychiatrist or psychologist) may be necessary. Many useful standardized
assessment tools exist. These include self-report questionnaires such as the
Hospital Anxiety and Depression Scale (HAD Scale; Zigmond and Smith, 1982), the
General Health Questionnaire (GHQ-30; Goldberg & Williams, 1988) and
A mental state examination of individuals
with fatigue should focus on observed behavioral features in addition to
symptoms reported by the patient. This includes psychomotor slowing, cognitive
impairment, odd interpersonal behavior, and angry/hostile responses. In
addition, it is important to evaluate the individualís risk of
Several psychiatric illnesses resemble CFS.
A history of prior or current depressive episodes does not exclude a diagnosis
of CFS. Based on the case definition, a history of psychiatric disorders (e.g.,
major depression with psychotic or melancholic features, bipolar affective
disorder, schizophrenia, delusional disorder, dementia, active substance or
alcohol abuse, anorexia nervosa or bulimia) generally prevents a diagnosis of
CFS being made because these illnesses preclude the reliable determination of
the core symptoms of CFS.
In other illnesses like SLE and MS,
debilitating chronic fatigue can be more prominent than rheumatologic or
neurologic symptoms, but the presence of objective physical findings, laboratory
abnormalities and illness progression point to an accurate diagnosis.
CFS is excluded if another plausible
explanation is found. Primary health care providers should treat confounding
conditions and re-evaluate as appropriate.
It should be noted that CFS and
fibromyalgia, closely related illnesses, may coexist in the same patient.
Fibromyalgia differs mainly in its emphasis on musculoskeletal pain rather than
fatigue; however, treatment options are similar to CFS with an emphasis on
specific symptom relief. The diagnosis of fibromyalgia requires the detection of
11 out of 18 discrete
tender points and the presence of widespread muscle pain.
In addition to fibromyalgia, investigative
evidence shows that there are other conditions that present with symptoms that
overlap with CFS: Gulf War Illnesses (GWI) and multiple chemical sensitivity
(MCS). Gulf War Illness is a recognized condition, however, MCS remains
In 1998 the Centers for Disease Control and
Prevention (CDC) developed a case definition for ďchronic multi-symptom illnessĒ
to classify GWI, as follows:
One or more chronic (more than six months)
symptoms from two of the three following categories:
- Mood and cognition (depression,
difficulty concentrating, moodiness, anxiety, word-finding difficulties, sleep
- Musculoskeletal (joint pain, joint
stiffness, muscle pain)
The CDC further classified patients by
severity of illness: 1) mild-moderate or 2) severe.