Defining Essential Features of Myalgic Encephalomyelitis and Chronic Fatigue Syndrome

Abstract

Considerable debate surrounds the search for the defining features of patients with Myalgic Encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Current case definitions were created through clinical consensus. Failure to operationalize these case definitions has led to considerable variability in the identification of patients. In addition, some case definitions (e.g., Fukuda et al., 1994) do not require cardinal symptoms of this illness, where as other case definitions do require core symptoms of this illness (Carruthers et al., 2003, 2011), and these latter case criteria appear to identify a more impaired group of patients. Criterion variance is most likely to occur when operationally explicit criteria do not exist for diagnostic categories (Spitzer, Endicott, & Robins, 1978), or when there are varying criteria for contrasting case definitions, which is an impediment to the research in this field. To deal with this problem, it is possible to differentiate those that meet more loosely defined criteria from those that are more narrowly and defined, thus differentiating CFS from ME. In order to progress the search for biological markers and effective treatments, essential features need to be operationalized and broadly used in order to increase the probability that individuals included in samples have the same underlying illness.

Telephone-administered versus live group cognitive behavioral stress management for adults with CFS

“…Again, L-CBSM revealed a significant reduction in the severity of these symptoms ( p ’s=.046 to .003; partial ε 2 =.09 – .18) compared to no changes in T-CBSM. Effects on PEM and unrefreshing sleep severity, among the most common CFS symptoms [31], are plotted in Figures 1 and 2. Again, results were unaffected by controlling for session attendance.…”

Clinical criteria versus a possible research case definition in chronic fatigue syndrome/myalgic encephalomyelitis

“…This suggests that it might be worthwhile to categorize this group of less impaired patients in studies, and continue to investigate characteristics of this group. This group might very well represent a larger group of individuals seeking help for their symptoms, as about one out of 20 people seems to have chronic fatigue, versus much smaller percentages for those meeting CFS or ME criteria [32]. Even though this group is not as impaired, they still need to be both diagnosed and treated with respect and care by medical personnel.…”

A perspective on causation of the chronic fatigue syndrome by considering its nosology

“…Furthermore, matters are complicated by considering whether CFS is the same or a different condition from myalgic encephalomyelitis (ME). Some authors consider that ME is different from CFS, whereas others suggest they are synonymous …”

“…Psychiatric illnesses are also commonly found in patients with CFS. The commonest associations are with depressive illnesses, particularly major depressive disorder and dysthymia . But anxiety disorders are also found, particularly generalized anxiety disorder .…”

“…Some authors consider that ME is different from CFS, whereas others suggest they are synonymous. 11,12 ME was first described in a 1956 Lancet editorial describing epidemics of fatigue with neurological symptoms and signs. 13 The Royal Free hospital epidemic of the early 1950s provided a typical description of an epidemic of ME.…”