Prospective study of the prognosis of unexplained chronic fatigue in a clinic-based cohort

The association of major life events with chronic fatigue

OBJECTIVE

Major life events have been associated with the onset of unexplained chronic fatigue (CF) and with variability in illness course. The purpose of this study was to characterize the associations of major life events with illness status over time.

METHOD

Sentinel measures of clinical status were collected four times over 18 months in a cohort of 99 persons with CF; participants also were interviewed regarding major life events, which were independently rated by observers.

RESULTS

Over time, more major life events attributed to CF predicted a worse clinical course, suggesting that illness-related major life events rather than stressful life events in general are associated with worse clinical status for persons with CF.

CONCLUSION

This study adds to the literature regarding specific types of life events' relationship to illness course, which has implications for the management of CF.

Longitudinal associations of lymphocyte subsets with clinical outcomes in chronic fatigue syndrome

Background

Chronic fatigue syndrome (CFS) is characterized by prolonged fatigue and other physical and neurocognitive symptoms. Some studies suggest that CFS is accompanied by disruptions in the number and function of various lymphocytes. However, it is not clear which lymphocytes might influence CFS symptoms.

Purpose

To determine if patient reported fatigue symptoms and physical functioning scores significantly changed across time with lymphocyte counts as evidence of a relation among chronic fatigue symptoms and the immune response.

Methods

The current longitudinal, naturalistic study assessed the cellular expression of three lymphocyte subtypes -- natural killer (NK) cells (CD3-CD16+ and CD3-CD56+) and naïve T cells (CD4+CD45RA+) -- to determine whether changes in lymphocytes at 4 time points across 18 months were associated with clinical outcomes, including CFS symptoms, physical functioning, and vitality, among patients with chronic fatigue.. Latent growth curve models were used to examine the longitudinal relationship between lymphocytes and clinical outcomes.

Results

Ninety-three patients with Fukuda-based CFS and seven with non-CFS fatigue provided study data. Results indicated that higher proportions of naïve T cells and lower proportions of NK cells were associated with worse physical functioning, whereas higher proportions of NK cells (CD3-CD16+) and lower proportions of naïve T cells were associated with fewer CFS symptoms.

Conclusion

These findings suggest that lymphocytes are modestly related to clinical outcomes over time.

Longitudinal outcomes associated with significant other responses to chronic fatigue and pain

This study investigated significant others' behavior associated with fatigue, pain, and mental health outcomes among 68 individuals with chronic fatigue (43% also had fibromyalgia) over 18 months. More negative significant others' responses were associated with more pain, poorer physical and mental health, and more fatigue-related symptoms over time. More fibromyalgia tender points covaried with more solicitous significant others' responses over time. Better mental health covaried with more distracting significant others' responses over time. The results are discussed in terms of theoretical models of the role of perceived significant others' responses on patient outcomes and recommendations for future research.

Neurocognitive complaints and functional status among patients with chronic fatigue syndrome and fibromyalgia

PURPOSE

The purpose of this study was to conduct a longitudinal examination of cognitive complaints and functional status in patients with chronic fatigue syndrome (CFS) alone and those who also had fibromyalgia (CFS/FM).

METHODS

A total of 93 patients from a tertiary care fatigue clinic were evaluated on four occasions, each 6 months apart. Each evaluation included a tender point assessment, and self-reported functional status and cognitive complaints.

RESULTS

Patients with CFS/FM reported significantly worse physical functioning, more bodily pain, and more cognitive difficulties (visuo-perceptual ability and verbal memory) than patients with CFS alone. Over time, bodily pain decreased only for participants with CFS alone. Verbal memory problems were associated with more bodily pain for both patient groups, whereas visuo-perceptual problems were associated with worse functional status for patients with CFS alone.

CONCLUSIONS

This study adds to the literature on functional status, longitudinal course, and cognitive difficulties among patients with CFS and those with CFS and FM. The results suggest that patients with CFS/FM are more disabled, have more cognitive complaints, and improve more slowly over time than patients with CFS alone. Specific cognitive difficulties are related to worse functional status, which supports the addition of cognitive difficulties to the FM case criteria.

Decreased work ability associated to indoor air problems--An intervention (RCT) to promote health behavior

INTRODUCTION

Indoor air problems may induce respiratory irritation and inflammation. In occupational settings, long-lasting non-specific building-related symptomatology, not fully medically explained, is encountered. The symptomatology may lead to illness, avoidance behavior and decreased work ability. In Finland, investigations of workers suspected of occupational asthma have revealed excess disability. There are no well-established clinical practices for the condition.

OBJECTIVE

The aim was to develop a clinical intervention for patients with non-specific indoor air-related symptoms and decreased work ability.

METHODS

A randomized controlled trial including psychoeducation and promotion of health behavior was carried out in 55 patients investigated for causal relationship between work-related respiratory symptoms and moisture damaged workplaces. Inclusion criteria for disability was the work ability score (WAS)≤7 (scale 0-10) and indoor air-related sick leave ≥14 days the preceding year. After medical evaluation and the 3-session counseling intervention, follow-up at 6-months was assessed using self-evaluated work-ability, sick leave days, quality of life, and illness worries as outcome measures.

RESULTS

The mean symptom history was 55.5 months. 82% (45 out of 55) had asthma with normal lung function tests in most cases, although reporting abundant asthma symptoms. 81% of patients (39/48) had symptomatology from multiple organ systems without biomedical explanation, despite environmental improvements at work place. At the psychological counseling sessions, 15 (60%) patients of the intervention (INT, n=25) group showed concerns of a serious disease and in 5 (20%), concerns and fears had led to avoidance and restricted personal life. In the 6-month follow-up, the outcomes in the INT group did not differ from the treatment as usual group.

CONCLUSION

No intervention effects were found. Patients shared features with medically unexplained symptoms and sick building syndrome or idiopathic environmental intolerance. Long environment-attributed non-specific symptom history and disability may require more intensive interventions. There is a need for improved recognition and early measures to prevent indoor-associated disability.

TRIAL REGISTRATION NUMBER

Single-center randomized controlled trial (ISRCTN33165676).

Physical symptom attributions: a defining characteristic of somatoform disorders?

OBJECTIVES

We examined whether primary care patients were more likely to perceive a current health problem as 'physical illness only' as opposed to entailing psychological difficulties if they had a comorbid somatoform disorder compared to patients who had (a) both comorbid somatoform disorder and anxiety/depression or (b) comorbid anxiety and/or depression, and a reference group of (c) patients with well-defined physical disease. We examined whether attributions predicted future health expenditures.

METHODS

A total of 1209 of 1785 patients completed questions on patient-perceived illness. The physicians diagnosed the current health problem. A stratified subsample was interviewed using the Schedules for Clinical Assessment in Neuropsychiatry. Health expenditure was obtained from registers for a 2-year period.

RESULTS

The belief that the current health problem was only physical was endorsed by 86% of patients presenting physical disease, 58% of patients with somatoform disorders, 29% of patients with both somatoform disorders and anxiety/depression and 24% of patients with anxiety or depressive disorders (χ2=269.2, df=3, P<.0001). In a multiple regression model, a 'physical illness only' perception predicted lower health expenditures [β = -0.31, 95% confidence interval (-0.55; -0.07), P=.013].

CONCLUSIONS

The prevalent assumption that physical symptom attributions are a central aspect in somatoform disorders is not supported by the current study.

Myelophil ameliorates brain oxidative stress in mice subjected to restraint stress

We evaluated the pharmacological effects of Myelophil, a 30% ethanol extract of a mix of Astragali Radix and Salviae Radix, on oxidative stress-induced brain damage in mice caused by restraint stress. C57BL/6 male mice (eight weeks old) underwent daily oral administration of distilled water, Myelophil (25, 50, or 100mg/kg), or ascorbic acid (100mg/kg) 1h before induction of restraint stress, which involved 3h of immobilization per day for 21days. Nitric oxide levels, lipid peroxidation, activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione redox system enzymes), and concentrations of adrenaline, corticosterone, and interferon-γ, were measured in brain tissues and/or sera. Restraint stress-induced increases in nitric oxide levels (serum and brain tissues) and lipid peroxidation (brain tissues) were significantly attenuated by Myelophil treatment. Restraint stress moderately lowered total antioxidant capacity, catalase activity, glutathione content, and the activities of glutathione reductase, glutathione peroxidase, and glutathione S-transferase; all these responses were reversed by Myelophil. Myelophil significantly attenuated the elevated serum concentrations of adrenaline and corticosterone and restored serum and brain interferon-γ levels. Moreover, Myelophil normalized expression of the genes encoding monoamine oxidase A, catechol-O-methyltransferase, and phenylethanolamine N-methyltransferase, which was up-regulated by restraint stress in brain tissues. These results suggest that Myelophil has pharmacological properties protects brain tissues against stress-associated oxidative stress damage, perhaps in part through regulation of stress hormones.

A natural history study of chronic fatigue syndrome

OBJECTIVE

There is a need for natural history chronic fatigue syndrome (CFS) studies from random, community-based, multi-ethnic populations.

DESIGN

The present study examined the course of CFS from Wave 1 to Wave 2, which spanned over a ten year period of time, and, assessed whether socio-environmental and symptomatology factors were associated with CFS status over the ten year period.

RESULTS

There was relative stability over time on critical measures of disability, fatigue, support, optimism and coping over time. One cardinal symptoms of CFS, post-exertional malaise, best differentiated the CFS group from the others. By Wave 2, of the original group of 32 individuals diagnosed with CFS, 4 had died, and 24 were found and agreed to be re-evaluated, and of this group, 16 continued to have CFS, 5 developed exclusionary illnesses, 2 were classified as Idiopathic chronic fatigue, and one had remitted.

CONCLUSIONS

The current study found that over time in a community-based sample, unbiased by help seeking behavior the CFS group remained rather ill with a variety of different conditions over time.

Towards positive diagnostic criteria: a systematic review of somatoform disorder diagnoses and suggestions for future classification

OBJECTIVES

The classification of somatoform disorders is currently being revised in order to improve its validity for the DSM-V and ICD-11. In this article, we compare the validity and clinical utility of current and several new diagnostic proposals of those somatoform disorders that focus on medically unexplained somatic symptoms.

METHODS

We searched the Medline, PsycInfo, and Cochrane databases, as well as relevant reference lists. We included review papers and original articles on the subject of somatoform classification in general, subtypes of validity of the diagnoses, or single diagnostic criteria.

RESULTS

Of all diagnostic proposals, only complex somatic symptom disorder and the Conceptual Issues in Somatoform and Similar Disorders (CISSD) example criteria reflect all dimensions of current biopsychosocial models of somatization (construct validity) and go beyond somatic symptom counts by including psychological and behavioral symptoms that are specific to somatization (descriptive validity). Predictive validity of most of the diagnostic proposals has not yet been investigated. However, the number of somatic symptoms has been found to be a strong predictor of disability. Some evidence indicates that psychological symptoms can predict disease course and treatment outcome (e.g., therapeutic modification of catastrophizing is associated with positive outcome). Lengthy symptom lists, the requirement of lifetime symptom report (as in abridged somatization), complicated symptom patterns (as in current somatization disorder), and imprecise definitions of diagnostic procedures (e.g., missing symptom threshold in complex somatic symptom disorder) reduce clinical utility.

CONCLUSION

Results from the reviewed studies suggest that, of all current and new diagnostic suggestions, complex somatic symptom disorder and the CISSD definition appear to have advantages regarding validity and clinical utility. The integration of psychological and behavioral criteria could enhance construct and descriptive validity, and confers prospectively relevant treatment implications. The incorporation of a dimensional approach that reflects both somatic and psychological symptom severity also has the potential to improve predictive validity and clinical utility.

An investigation of victimization and the clinical course of chronic fatigue syndrome

Medically unexplained syndromes, including chronic fatigue syndrome (CFS), have been associated with victimization in childhood and adulthood. The purpose of this study was to examine the associations of victimization experiences in childhood and adulthood with functional status and illness severity in a sample of patients with CFS using longitudinal data. In the sample of 93 patients with CFS, childhood abuse and neglect had greater impact than adulthood victimization. Overall, victimization experiences in childhood demonstrated modest associations with clinical outcomes in CFS, although several victimization experiences were in the opposite direction of expectations. Victimization predicted worse outcomes, but not worsening outcomes over time.

Patients with medically unexplained symptoms and their significant others: illness attributions and behaviors as predictors of patient functioning over time

OBJECTIVE

Previous research suggests that medically unexplained symptoms (MUS) are maintained in an interpersonal context. The current study examined MUS concurrently and prospectively by measuring specific interpersonal predictors of symptom severity and health care use.

METHODS

A total of 127 patients with MUS and their significant others were recruited through primary care offices and assessed with self-report questionnaires and structured interviews about illness attributions, illness behavior and responses, relationship quality, symptom severity, and health care use at baseline and 6-month follow-up.

RESULTS

Illness attributions and interpersonal illness behaviors of patients with MUS were cross-sectionally associated with illness attributions and responses of the patients' significant others. Relationship quality was related to specific illness behaviors and responses. Symptom severity at baseline was predicted by patients' somatic illness attributions. Symptom severity at 6-month follow-up was predicted by somatic illness attributions of patients and withdrawal of patients' significant others at baseline, but these predictors became insignificant when correcting for baseline symptomatology. Health care use at baseline was predicted by a greater amount of coping behavior and higher anxiety scores of patients, and health care use at 6-month follow-up was predicted by more attention-seeking behaviors and health care use of patients at baseline.

CONCLUSION

The results document the interpersonal influences on the maintenance of MUS. The perspective of significant others should be considered for enhancement of psychological approaches to the treatment of patients with MUS.

Which is more important for outcome: the physician's or the patient's understanding of a health problem? A 2-year follow-up study in primary care

OBJECTIVE

We sought to examine (1) whether the patients' and the family physicians' (FPs') beliefs about the nature of a health problem predict health outcomes and (2) whether the FPs were aware of their patients' beliefs.

METHODS

A 2-year follow-up study of 38 FPs and 1131 patients presenting with well-defined physical disease (n=922) or medically unexplained symptoms (MUS) (n=209) according to the FPs was conducted. Before the consultation, patients categorized their health problem as being either physical or both physical and psychological. After the consultation, the FPs judged their patients' understanding of the health problem. Outcome measures were (1) patient satisfaction (seven-item Patient Satisfaction Consultation Questionnaire), (2) self-perceived mental and physical health (component summaries of the Medical Outcome Study's Short Form: SF-36) and (3) health care use extracted from patient registers.

MAIN RESULTS

Patients with MUS according to the FPs and patients who believed that the nature of their health problem was both physical and psychological had higher health care use and worse self-rated health than patients in cases where both the FP and the patient had a physical understanding. Patients presenting MUS were more dissatisfied with the consultation than patients with well-defined physical disease. Overall, the FPs' perceptions of their patients' understanding were accurate in 82% of the consultations, but when the patients had a both physical and psychological understanding of their health problem, the FPs were right in only 26% of the consultations.

CONCLUSIONS

Both FPs' diagnoses and patients' beliefs predict important health outcomes such as patient satisfaction, use of health care and self-rated health.

Clinical assessment of the physical activity pattern of chronic fatigue syndrome patients: a validation of three methods

BACKGROUND

Effective treatment of chronic fatigue syndrome (CFS) with cognitive behavioural therapy (CBT) relies on a correct classification of so called 'fluctuating active' versus 'passive' patients. For successful treatment with CBT is it especially important to recognise the passive patients and give them a tailored treatment protocol. In the present study it was evaluated whether CFS patient's physical activity pattern can be assessed most accurately with the 'Activity Pattern Interview' (API), the International Physical Activity Questionnaire (IPAQ) or the CFS-Activity Questionnaire (CFS-AQ).

METHODS

The three instruments were validated compared to actometers. Actometers are until now the best and most objective instrument to measure physical activity, but they are too expensive and time consuming for most clinical practice settings. In total 226 CFS patients enrolled for CBT therapy answered the API at intake and filled in the two questionnaires. Directly after intake they wore the actometer for two weeks. Based on receiver operating characteristic (ROC) curves the validity of the three methods were assessed and compared.

RESULTS

Both the API and the two questionnaires had an acceptable validity (0.64 to 0.71). None of the three instruments was significantly better than the others. The proportion of false predictions was rather high for all three instrument. The IPAQ had the highest proportion of correct passive predictions (sensitivity 70.1%).

CONCLUSION

The validity of all three instruments appeared to be fair, and all showed rather high proportions of false classifications. Hence in fact none of the tested instruments could really be called satisfactory. Because the IPAQ showed to be the best in correctly predicting 'passive' CFS patients, which is most essentially related to treatment results, it was concluded that the IPAQ is the preferable alternative for an actometer when treating CFS patients in clinical practice.

Chronic fatigue: is it endocrinology?

Fatigue and stress-related illnesses often become diagnoses of exclusion after extensive investigation. 'Tired all the time' is a frequent reason for referral to the endocrine clinic, the implicit question being--is there a subtle endocrine pathology contributing to the patient's symptoms? Often initial assessment suggests not but there are no clear data to address the question of whether overt pathology will develop in the future. This study observed outcomes after five years in 101 consecutive and unselected referrals to secondary care for 'fatigue?cause', where initial assessment did not suggest treatable endocrine pathology. The findings suggest that the clinical diagnosis of fatigue, based on history and tests to exclude anaemia, hypothyroidism and diabetes, is secure: these patients do not subsequently demonstrate excess morbidity and mortality, and their presenting symptoms are not early features of significant endocrine pathology.

Chronic fatigue: an evolutionary concept analysis

AIM

This paper is a report of a concept analysis of chronic fatigue.

BACKGROUND

Fatigue is a prevalent symptom encompassing both acute and chronic manifestations. It is chronic fatigue that is most problematic because of its duration and impact on life quality. The rise in prevalence of chronic conditions will result in a need to address coexistent symptoms, clarification of which is needed. Chronic fatigue is one of the most common symptoms in chronic illness. Clarification of the concept and an understanding of its use by discipline are needed.

DATA SOURCES

The evolutionary method of concept analysis was used to ascertain the attributes, antecedents, consequences and surrogate terms for chronic fatigue. A review of the literature published between 1966 and 2007 was carried out to determine the contextual use of the concept of chronic fatigue among disciplines. Sources used for this analysis included CINAHL, Medline, PsychINFO and Social Work Abstracts and the search yielded 66 papers.

RESULTS

The chronic fatigue experience is associated with a multitude of physical, psychological and social factors. The defining attributes of chronic fatigue are constancy, abnormality, whole-body experience, inexplicability and disabling. The antecedents of chronic fatigue are physical disease, psychopathology, female gender and a history of abuse. Consequences found include social isolation and stigmatization, physical inactivity, psychological disturbances and a reduced quality of life.

CONCLUSION

Further research is needed to identify the aetiology of chronic fatigue and to address the social context of living with this disabling symptom.

'Physical or psychological?'- a comparative study of causal attribution for chronic fatigue in Brazilian and British primary care patients

OBJECTIVE

Causal attribution influences symptom experience, help-seeking behaviour and prognosis in chronic fatigue syndrome. We compared causal attribution of patients with unexplained chronic fatigue (UCF) in Brazil and Britain.

METHOD

Primary care attenders in São Paulo (n = 3914) and London (n = 2459) were screened for the presence of UCF. Those with UCF (São Paulo n = 452; London n = 178) were assessed for causal attribution (physical vs. psychosocial), perceived chronicity (i.e. reported duration of fatigue) and disability.

RESULTS

British UCF patients were more likely to attribute their fatigue to physical causes (adjusted odds ratio 1.70, P = 0.037) and perceived their fatigue to be more chronic (adjusted beta 0.15, P = 0.002). There was no significant difference in current disability (adjusted beta -0.01, P = 0.81).

CONCLUSION

Despite similar disability levels, UCF patients in different cultural settings presented different attributions and perceptions about their illness. Sociocultural factors may have an important role in shaping illness attribution and perception around chronic fatigue.

Venlafaxine reverses chronic fatigue-induced behavioral, biochemical and neurochemical alterations in mice

A state of chronic fatigue was produced in mice by subjecting them to forced swim inside a rectangular jar of specific dimensions everyday for a 6 min session for 15 days. Immobility period was recorded on alternate days. The effect of venlafaxine, a dual reuptake inhibitor of serotonin and norepinephrine was evaluated in this murine model of chronic fatigue. Venlafaxine was administered daily and on the days of testing, it was injected 30 min before forced swim session. On the 16th day i.e. 24 h after the last dose of venlafaxine, various behavioral, biochemical and neurotransmitter estimations in the brain were carried out. There was a significant increase in immobility period in vehicle treated mice on successive days, the maximum immobility score reaching on the 7th day and sustained till 15th day. Behavioral parameters revealed hyperlocomotion, anxiety response, muscle incoordination, hyperalgesia and memory deficit. Biochemical analysis showed a significant increase in lipid peroxidation, nitrite and myeloperoxidase levels and a decrease in the reduced glutathione (GSH) levels in brain homogenates. Further, there was a decrease in adrenal ascorbic acid following chronic forced swim. The neurotransmitter estimations in the brain samples revealed a decrease in norepinephrine, serotonin and dopamine levels on chronic exposure to forced swim for 15 days. Daily treatment with venlafaxine (8 and 16 mg/kg, i.p.) for 15 days produced a significant reduction in immobility period and reversed various behavioral, biochemical and neurotransmitter alterations induced by chronic fatigue. Venlafaxine could be of therapeutic potential in the treatment of chronic fatigue.

Explaining medically unexplained symptoms-models and mechanisms

We summarize the psychological mechanisms that have been linked to the development and maintenance of medically unexplained symptoms (MUS). Many models postulate that patients with MUS misinterpret physical sensations and show other cognitive abnormalities (e.g., an over-exclusive concept of health) that play a major role in symptom development. While there is strong evidence for the role of cognitive aspects, there is less evidence for their interaction with perceptual features (e.g., perceptual sensitivity, lowered perceptual threshold). Modern neuroimaging techniques show that the expectation of symptoms leads to the activation of brain areas corresponding to symptom perception, while distraction from symptoms reduces brain activity in perception areas. The frequently postulated monocausal organic attribution for physical sensations by patients with MUS needs to be modified, as many patients report multiple symptom attributions, including psychological. Symptom attributions and causal models depend on memorized concepts, and so memory processes need to be investigated in more detail. Aberrations in memory processes not only offer a link to understanding perceptual processes, but are also involved in doctor-patient interaction. This encounter is characterized by unsuccessful medical reassurance, which again involves memory processes. We conclude that psychological mechanisms such as expectation, distraction, and memory processes need to be integrated with biological models to aid understanding of MUS.

Long-term efficacy of cognitive-behavioral therapy by general practitioners for fatigue: a 4-year follow-up study

OBJECTIVE

In an earlier study, we found that cognitive-behavioral therapy (CBT) delivered by general practitioners (GPs) for fatigue among employees on sick leave was not effective after 12 months. In this study we aim to assess the long-term efficacy of CBT by GPs for fatigue. It was hypothesized that the intervention could prevent deterioration as well as relapse of fatigue complaints and relapse into absenteeism in the long term.

METHODS

Patients who participated in the original randomized controlled trial were followed up 4 years later. Fatigue and absenteeism were the main outcomes.

RESULTS

Fatigue and absenteeism were high in the intervention and control groups at the 4-year follow-up. There was no significant difference between the intervention group and the control group on fatigue and absenteeism. The intervention group however tended toward less-favorable outcomes as compared with the control group.

CONCLUSIONS

Like that of chronic fatigue syndrome, the prognosis of less-advanced fatigue is rather poor. CBT delivered by GPs is not effective in the long term.

Attribution of physical complaints to the air disaster in Amsterdam by exposed rescue workers: an epidemiological study using historic cohorts

BACKGROUND

In 1992 a cargo aircraft crashed into a residential area of Amsterdam. A troublesome aftermath followed, with rumors on potential toxic exposures and health consequences. Health concerns remained even though no excess morbidity was predicted in retrospective risk evaluations. This study aimed to assess to what extent the rescue workers attribute long-term physical complaints to this disaster, including its aftermath, and to examine associations between such attribution and types of exposure and background variables.

METHODS

Historic cohort study that collected questionnaire data on occupational disaster exposure, attribution of physical complaints, and background variables on average 8.5 years post-disaster. For the present study the workers who were exposed to the disaster were selected from the historic cohort, i.e. the professional firefighters (n = 334), police officers (n = 834), and accident and wreckage investigators (n = 241) who performed disaster-related tasks.

RESULTS

Across the three occupational groups, a consistent percentage (ranging from 43% to 49%) of exposed workers with long-term physical complaints attributed these to the disaster, including its aftermath. Those with more physical complaints attributed these to a stronger degree. Multivariate logistic regression analyses showed that attribution was significantly more often reported by firefighters who rescued people, and by police officers who reported the identification and recovery of or search for victims and human remains, clean-up, or security and surveillance of the disaster area; who witnessed the immediate disaster scene; who had a close one affected by the disaster; and who perceived the disaster as the worst thing that ever happened to them. Age, sex and educational level were not significantly associated with attribution.

CONCLUSION

This study provides further cross-sectional evidence for the role of causal attribution in post-disaster subjective physical health problems. After on average 8.5 years, almost a third (32%) of all the exposed workers, and almost half (45%) of the exposed workers with physical complaints, attributed these complaints to the disaster, including its aftermath. The similarity of the results across the occupational groups suggests a general rather than an occupation-specific attribution process. Longitudinal studies are needed to determine whether causal disaster attribution leads to persistence of post-disaster complaints and health care utilization.

Chronic fatigue syndrome: the need for subtypes

Chronic fatigue syndrome (CFS) is an important condition confronting patients, clinicians, and researchers. This article provides information concerning the need for appropriate diagnosis of CFS subtypes. We first review findings suggesting that CFS is best conceptualized as a separate diagnostic entity rather than as part of a unitary model of functional somatic distress. Next, research involving the case definitions of CFS is reviewed. Findings suggest that whether a broad or more conservative case definition is employed, and whether clinic or community samples are recruited, these decisions will have a major influence in the types of patients selected. Review of further findings suggests that subtyping individuals with CFS on sociodemographic, functional disability, viral, immune, neuroendocrine, neurology, autonomic, and genetic biomarkers can provide clarification for researchers and clinicians who encounter CFS' characteristically confusing heterogeneous symptom profiles. Treatment studies that incorporate subtypes might be particularly helpful in better understanding the pathophysiology of CFS. This review suggests that there is a need for greater diagnostic clarity, and this might be accomplished by subgroups that integrate multiple variables including those in cognitive, emotional, and biological domains.

A longitudinal study of physical activity and body mass index among persons with unexplained chronic fatigue

OBJECTIVE AND METHODS

A cohort of 100 patients with unexplained chronic fatigue (CF) was assessed longitudinally for 1.5 years to determine if physical activity (kcal expended), exercise capacity (VO(2)max), perceived exertion, and body mass index (BMI) changed over time and were associated with changes in CF-related clinical status.

RESULTS

BMI increased significantly over time but did not predict changes in clinical status. Increasing energy expenditure was associated with increasing vitality and decreasing CF symptom severity over time, and decreasing perceived exertion was associated with increasing physical functioning. However, increasing perceived exertion was also associated with increasing CF symptoms.

CONCLUSIONS

These data do not support models that posit associations between CF and deconditioning.

Predicting the two-year course of unexplained fatigue and the onset of long-term sickness absence in fatigued employees: results from the Maastricht Cohort Study

Because of the serious adverse consequences of unexplained fatigue, it is important to identify factors that determine the prognosis of unexplained fatigue and the onset of long-term sickness absence in fatigued employees. Analyses were based on the Maastricht Cohort Study, a prospective population-based cohort study among more than 12,000 employees. Severely fatigued employees who were not on sick leave (n = 2108) were selected at baseline and followed up at six time points during the course of 2 years. Point prevalences of severe fatigue (59% to 63%) and long-term sickness absence (1.8% to 3.1%) among participants were fairly stable at all consecutive time points. Lower levels of fatigue severity, work-related exhaustion and anxious mood, absence of conflicts with colleagues, and good self-rated health at baseline were predictors of the onset of recovery from fatigue in survival analyses. Older age, low decision authority, female sex, working in nightshift, a physical attribution of fatigue, and a history of absenteeism were predictors of the onset of long-term absenteeism. The course of unexplained fatigue in employees is characterized by remission and relapse in time while the absolute risk of long-term absenteeism is small. Given the broad range of predictors, it appears that fatigue and long-term sickness absence entangle different underlying processes. Our findings underscore the notion that prevention and treatment of fatigue should be aimed at health perception and emotional well-being.