Fatigue: Biomedicine, Health & Behavior - Volume 5, Issue 2, 2017

Volume 5, Issue 2, 2017

 * Symptom variability following acute exercise in myalgic encephalomyelitis/chronic fatigue syndrome: a perspective on measuring post-exertion malaise"Abstract - Background: Consensus for an operational definition of post-exertion malaise (PEM) and which symptoms best characterize PEM has not been established and may be due to variability within and between studies. Purpose: Determine the magnitude of the effect of maximal and submaximal physical exertion on multiple myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) symptoms that are associated with PEM and explore variability among two studies in which mood, fatigue, and pain symptoms were measured before and after exercise. Methods: Symptoms were measured before, and 48 and 72 hours after exercise in study 1 (ME/CFS = 13; Controls = 11) and before and 24 hours after exercise in study 2 (ME/CFS = 15, Controls = 15). Between-study variability was examined by comparing Hedges d effect sizes (95% CI) from studies 1 and 2. Within-patient group variability was examined via inspection of dot density plots. Results: In study 1, large increases in general fatigue (Δ = 1.05), reduced motivation (Δ = 0.93), feelings of fatigue (Δ = 0.90), feelings of confusion (Δ = 0.93), and total mood disturbance (Δ = 0.90) were found at 72 hours. In study 2, a large increase in affective/sensory pain (Δ = 0.79) was found at 24 hours. Dot density plots in both studies revealed substantial variability among people with ME/CFS relative to healthy control participants."
 * Clinical criteria versus a possible research case definition in chronic fatigue syndrome/myalgic encephalomyelitis "Abstract - Background: The Institute of Medicine (IOM) recently developed clinical criteria for what had been known as chronic fatigue syndrome. Given the broad nature of the clinical IOM criteria, there is a need for a research definition that would select a more homogenous and impaired group of patients than the IOM clinical criteria. At the present time, it is unclear what will serve as the research definition. Purpose: The current study focused on a research definition which selected homebound individuals who met the four IOM criteria, excluding medical and psychiatric co-morbidities. Methods: Our research criteria were compared to those participants meeting the IOM criteria. Those not meeting either of these criteria sets were placed in a separate group defined by six or more months of fatigue. Data analyzed were from the DePaul Symptom Questionnaire and the 36-item Short-Form Health Survey (SF-36). Due to unequal sample sizes and variances, Welch’s F tests and Games-Howell post-hoc tests were conducted. Results: Using a large database of over 1000 patients from several countries, we found that those meeting a more restrictive research definition were even more impaired and more symptomatic than those meeting criteria for the other two groups. Conclusion: Deciding on a particular research case definition would allow researchers to select more comparable patient samples across settings, and this would represent one of the most significant methodologic advances for this field of study."
 * Two year follow-up of sleep diaries and polysomnography in chronic fatigue syndrome: a cohort study "Abstract - Background: Chronic fatigue syndrome (CFS) is a prevalent and debilitating symptom complex of unknown aetiology. Up to 96.8% of people with CFS report unrefreshing sleep and many describe, in qualitative interviews, changes in sleep over the course of their illness. Purpose: To establish whether subjective and objective sleep parameters change over a two-year follow-up period in patients with CFS. Methods: Twenty-two participants with CFS were recruited during routine consultations at a clinic in the North-East of England. All had their sleep characterised in a previously published cross-sectional study. Two were excluded from this analysis because they fulfilled criteria for a primary sleep disorder. The remaining 20 were contacted and 15 repeated fatigue- and sleep-quality questionnaires and sleep diaries, two years after their sleep was first characterised. Seven participants also repeated two consecutive nights of polysomnography. Paired statistical tests were used to compare follow-up with baseline measures. Results: Subjective questionnaires and sleep dairies did not show differences over two years follow-up. However, polysomnography demonstrated a higher proportion of stage one sleep (P < .01) and more awakenings per hour (P = .04) at follow-up. Conclusions: This study is the first to longitudinally assess sleep parameters in people with CFS. The results suggest that subjective perceptions of sleep remain stable, although objective measures indicated a tendency towards increased periods of lighter sleep. However, the small number of participants increases the likelihood that observed differences are Type I errors."
 * Patients diagnosed with Myalgic encephalomyelitis/chronic fatigue syndrome also fit systemic exertion intolerance disease criteria"Abstract - Background: Myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) remains undiagnosed in up to 91% of patients. Recently, the United States-based Institute of Medicine (IOM) developed new diagnostic criteria, naming it systemic exertion intolerance disease (SEID). Purpose: We examined how subjects fit SEID criteria and existing ME/CFS case definitions early in their illness. Methods: A total of 131 subjects fitting 1994 Fukuda CFS criteria at the time of study recruitment completed a survey of symptoms they experienced during their first 6 months of illness. Symptoms were drawn from SEID and existing criteria (1994 Fukuda, 2003 Canadian Consensus Criteria (CCC), and 2011 Myalgic Encephalomyelitis-International Consensus Criteria (ME-ICC)). We calculated and compared the number/percentage of subjects fitting single or combinations of case definitions and the number/percentage of subjects with SEID experiencing orthostatic intolerance (OI) and/or cognitive impairment. Results: At 6 months of illness, SEID criteria identified 72% of all subjects, similar to when Fukuda criteria (79%) or the CCC (71%) were used, whereas the ME-ICC selected for a significantly lower percentage (61%, p < .001). When severity/frequency thresholds were added to the Fukuda criteria, CCC and ME-ICC, the percentage of these subjects also fitting SEID criteria increased to 93%, 97%, and 95%. Eighty-seven percent of SEID subjects endorsed cognitive impairment and 92%, OI; 79% experienced both symptoms. Conclusions: SEID criteria categorize a similar percentage of subjects as Fukuda criteria early in the course of ME/CFS and contain the majority of subjects identified using other criteria while requiring fewer symptoms. The advantage of SEID may be in its ease of use."
 * Letter to the Editor - Comment on: Differing case definitions point to the need for an accurate diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome, by Frank N.M. Twisk.