Current research indicates that many healthcare professionals are unfamiliar or uncomfortable with and/or hold misconceptions about myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS). This is not surprising as medical schools, healthcare institutions, and other resources rarely discuss this medical condition in-depth. This talk will focus on important epidemiological features of ME/CFS and address common misconceptions. We will also describe areas where research is limited and discuss factors and barriers impeding research.

Background: Epidemiologic studies of myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) have examined different aspects of this disease separately but few have explored them together. Objective: Describe ME/CFS onset and course in one cohort. Methods: 150 subjects fitting Fukuda 1994 CFS criteria completed a detailed survey concerning the initial and subsequent stages of their illness. Descriptive statistics, scatterplots, line graphs, and tables were used to illustrate prevalence and patterns of characteristics. Results: The most common peri-onset events reported by subjects were infection-related episodes (64%), stressful incidents (39%), and exposure to environmental toxins (20%). For 38% of subjects, more than 6 months elapsed from experiencing any initial symptom to developing the set of symptoms comprising their ME/CFS. Over time, the 12 most common symptoms persisted but declined in prevalence, with fatigue, unrefreshing sleep, and flu-like symptoms declining the most (by 21%-24%). Conversely, cognitive symptoms changed the least in prevalence, rising in symptom ranking. Pregnancy, menopause, and menstrual cycles exacerbated many women’s symptoms. Fatigue-related function was not associated with duration of illness or age; during the worst periods of their illness, 48% of subjects could not engage in any productive activity. At the time of survey, 47% were unable to work and only 4% felt their condition was improving steadily with the majority (59%) describing a fluctuating course. Conclusions: Our findings concerning onset events, function, and overall course reinforce those of prior studies while providing new details about how symptoms change over time. Studying the onset and course of ME/CFS can offer further insight into and possible solutions to the diagnosis, etiology, pathophysiology, and treatment of this condition.

In the absence of a diagnostic laboratory test or biomarker, ME/CFS is recognized using a case definition. The Institute of Medicine has recommended a clinical case definition, and several other definitions are in use for research and epidemiologic studies. The long duration of illness, differing modes of onset, presence of other medical conditions, waxing and waning of symptoms and the number and diversity of medications all contribute to the heterogeneity of ME/CFS patients. Publications generally specify the case definition that was used to classify participants, but often fail to give details about how the definition was applied. Descriptions of study participants are often limited, making it hard to compare findings. Standardizing the approach to data collection on demographics, medical history, and illness domains has the potential to advance the field. This prompted initiation of the ME/CFS Common Data Element project by the National Institute of Neurological Disorders and Stroke and the Centers for Disease Control and Prevention.

Health professionals and patients often disagree in relation to the nature and causation of ME/CFS, and researchers and clinicians have so far failed to reach a consensus on its diagnosis and management. Although some still classify people presenting with symptoms compatible with ME/CFS as belonging to a wide group of patients with medically unexplained symptoms, there is growing research evidence on pathophysiological abnormalities enabling the description and characterization of a distinct clinical entity. While there is now ample recognition that ME/CFS represents a significant public health problem, there are still uncertainties in how ME/CFS should be defined and cases stratified. There are major challenges in describing the epidemiology of the disease and to determine and quantify the needs of people affected and the gaps in health and other services provision. Drawing from examples from the United Kingdom, this presentation will focus on the challenges involved in assessing health needs for people with ME/CFS; in planning services that are responsive to the needs of this population; and in developing a coherent research strategy that offers the best prospects of outputs that can be translated into clinical and societal benefits.