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PubMedDate not supplied

Prevalence of chronic fatigue syndrome in Italian patients with persistent fatigue.

Our study was carried out to determine the prevalence of chronic fatigue syndrome (CFS) within a selected population of patients suffering from persistent fatigue. We studied subjects with recurrent or persistent fatigue lasting 6 months and fulfilling at least four minor Center for Disease Control (CDC) criteria for the diagnosis of CFS. Evaluation included both clinical examination and laboratory testing. All subjects filled out a questionnaire specifically designed to gain information about the length and severity of symptoms, and patients with a previously diagnosed illness associated with fatigue were excluded. The study was carried out at the Fatigue Clinic of an internal medicine unit (Clinica Medica I) of the University of Rome "La Sapienza". Sixty-three subjects, residents of the Lazio region (central Italy), completed the diagnostic assessment. Alternative diagnoses were established in 37 (59%) of the 63 patients. A diagnosis of CFS based on the CDC criteria was established in only 6 cases. In 2 subjects, CFS had appeared following infectious mononucleosis, and no definitive diagnosis could be formulated for 18 patients. In Italy, CFS seems to be an infrequent cause of severe and persistent fatigue in a selected population. Numerous morbid conditions may be responsible for a clinical picture closely resembling CFS. We recommend that patients suffering from fatigue be thoroughly evaluated.

Adolescent↗
PubMed1993

Prevalence of fatigue and chronic fatigue syndrome in a primary care practice.

BACKGROUND: Our goals were to determine the prevalence of unusual, debilitating fatigue and the frequency with which it was associated with the chronic fatigue syndrome (CFS) or other physical or psychological illness in an outpatient clinic population. METHODS: We prospectively evaluated a cohort of 1000 consecutive patients in a primary care clinic in an urban, hospital-based general medicine practice. The study protocol included a detailed history, physical examination, and laboratory and psychiatric testing. RESULTS: Five patients who came because of CFS studies were excluded. Of the remaining 995, 323 reported fatigue, and 271 (27%) complained of at least 6 months of unusual fatigue that interfered with their daily lives. Of the 271, self-report or record review revealed a medical or psychiatric condition that could have explained the fatigue in 186 (69%). Thus, 85 (8.5%) of 995 patients had a debilitating fatigue of at least 6 months' duration, without apparent cause. Of these patients, 48 refused further evaluation, and 11 were unavailable for follow-up; 26 completed the protocol. Three of the 26 were hypothyroid, and one had a major psychiatric disorder. Of the remaining 22 patients, three met Centers for Disease Control and Prevention criteria for CFS, four met British criteria, and 10 met the Australian case definition. The point prevalences of CFS were thus 0.3% (95% confidence interval [CI], 0% to 0.6%), 0.4% (95% CI, 0% to 0.8%), and 1.0% (95% CI, 0.4% to 1.6%) using the Centers for Disease Control and Prevention, British, and Australian case definitions, respectively. These estimates were conservative, because they assumed that none of the patients who refused evaluation or were unavailable for follow-up would meet criteria for CFS. CONCLUSIONS: While chronic, debilitating fatigue is common in medical outpatients, CFS is relatively uncommon. Prevalence depends substantially on the case definition used.

Adult↗
PubMed2006

Efficacy of darbepoetin alfa in alleviating fatigue and the effect of fatigue on quality of life in anemic patients with lymphoproliferative malignancies.

Anemia-related fatigue in cancer patients reduces health-related quality of life (HRQOL). These analyses evaluate the effect of hemoglobin level on fatigue and examine the relationship between improved fatigue and HRQOL. Data were collected during a multicenter, randomized trial involving 344 anemic patients with lymphoproliferative malignancies receiving chemotherapy and darbepoetin alfa or placebo. At baseline, interim study visits, and end of treatment, patients completed an HRQOL questionnaire. Improved hemoglobin levels were significantly associated (P < 0.001) with improved fatigue. Mean change in the Functional Assessment of Cancer Therapy (FACT) Fatigue score was 5.9 points greater when hemoglobin improved > 2 g/dl than when it declined. Patients experiencing a clinically meaningful improvement in fatigue reported significantly (P < 0.001) greater improvements in all other scales, except the FACT Social subscale. Managing anemia-related fatigue appears to have a positive impact on HRQOL, enhancing cancer patients' activity levels, mood, and perceived overall health.

Aged↗
PubMedDate not supplied

Measurement of fatigue in HIV-positive adults: reliability and validity of the Global Fatigue Index.

Fatigue is among the most common and distressing symptoms in patients with HIV/AIDS. Little is known about the clinical assessment of fatigue, especially in patients using highly active antiretroviral regimens. The purpose of this study was to evaluate the psychometric properties of the Global Fatigue Index (GFI) in a community-based sample of 209 patients with HIV/AIDS. The GFI is a measure that quantifies five dimensions of fatigue from the Multidimensional Assessment of Fatigue instrument into one score. To assess construct validity, the study included measures of depression, perceived stress, activities of daily living (ADLs), health behaviors, and clinical markers. Cronbach's alpha was calculated for internal consistency reliability, and factor analysis and bivariate correlations were conducted. The GFI was found to be easily self-administered, reliable, and a valid measure of overall fatigue burden in an HIV population. This instrument may be used by clinicians and researchers for assessing fatigue.

Adult↗
PubMed2002

Fatigue severity, attributions, medical utilization, and symptoms in persons with chronic fatigue.

This study examined the roles of ethnicity, gender, and socioeconomic status (SES) in predicting fatigue severity, symptoms, medical utilization, and attributions among a sample of individuals with chronic fatigue. Using path analysis, a model was tested and revised. In the new model, gender predicted fatigue, ethnicity predicted attributions, fatigue predicted medical utilization and attributions, and attributions predicted medical utilization. Women reported more fatigue and were more likely to feel that stress and depression were causing their fatigue. Higher-SES participants were more likely to cite stress and overwork as causing their fatigue. Latinos reported more physical symptoms than African Americans and Whites. The implications of these results are discussed.

Chronic Disease↗
PubMed1998

Measurement of fatigue in cancer patients: development and validation of the Fatigue Symptom Inventory.

Although fatigue is one of the most common and debilitating symptoms experienced by cancer patients, it has received little systematic attention. This situation is due in large part to the lack of adequate instruments to measure fatigue. The primary aim of this study was to validate a newly developed measure of fatigue for use with cancer patients: the Fatigue Symptom Inventory (FSI). This 13 item self-report measure was designed to measure the intensity and duration of fatigue and its impact on quality of life. The psychometric properties of the FSI were assessed in women undergoing treatment for breast cancer, women who had completed treatment for breast cancer and women with no history of cancer. A seven-item interference subscale was found to have good internal consistency, with alpha coefficients above 0.90 in all three groups. The complete FSI was found to have rather weak to moderate test-retest reliability among patients in active treatment and healthy comparison subjects assessed on three separate occasions. Convergent validity was demonstrated using comparisons with existing measures of fatigue. Construct validity was demonstrated using comparisons between and within groups as well as comparisons with measures of anxiety and depression. Overall, the FSI was established as a valid and reliable measure of fatigue in cancer patients and healthy individuals. Suggestions are made for the potential application of the measure in clinical research.

Adult↗
PubMed1994

Measuring the functional impact of fatigue: initial validation of the fatigue impact scale.

The fatigue impact scale (FIS) was developed to improve our understanding of the effects of fatigue on quality of life. The FIS examines patients' perceptions of the functional limitations that fatigue has caused over the past month. FIS items reflect perceived impact on cognitive, physical, and psychosocial functioning. This study compared 145 patients referred for investigation of chronic fatigue (ChF) with 105 patients with multiple sclerosis (MS) and 34 patients with mild hypertension (HT). Internal consistency for the FIS and its three subscales was > .87 for all analyses. Fatigue impact was highest for the ChF group although the MS group's reported fatigue also exceeded that of the HT group. Discriminant function analysis correctly classified 80.0% of the ChF group and 78.1% of the MS group when these groups were compared. This initial validation study indicates that the FIS has considerable merit as a measure of patient's attribution of functional limitations to symptoms of fatigue.

Adult↗
PubMed1993

Muscle fatigue: clinical implications for fatigue assessment and neuromuscular electrical stimulation.

Muscle fatigue can be defined as a decrease in the force-generating ability of a muscle that resulted from recent activity. Recent studies of muscle fatigue are reviewed that are relevant to two areas of interest to physical therapists: clinical assessment of muscle fatigue and neuromuscular electrical stimulation. Volitional and electrical tests have been used to quantify muscle fatigue. Several variations on each type of test are discussed, as are the possible sites in which fatigue might occur. The rate of fatigue during the therapeutic application of electrical stimulation of skeletal muscle is much greater than that seen during volitional contractions. Factors contributing to this phenomenon are examined. The unique requirements affecting how stimulus variables can be manipulated to minimize muscle fatigue in three specific therapeutic uses of neuromuscular electrical stimulation are addressed.

Electric Stimulation↗
PubMedDate not supplied

Significant other responses are associated with fatigue and functional status among patients with chronic fatigue syndrome.

OBJECTIVE: The predictive power of partners' responses to illness behavior for illness outcomes was investigated among couples in which one person had chronic fatigue syndrome (CFS). METHODS: One hundred nineteen participants who met case-definition criteria for CFS and were living with a significant other (SO) completed self-report measures of relationship satisfaction, responses of their SO to fatigue symptoms, and outcome measures of fatigue and functional status. RESULTS: The results indicated that more frequent solicitous SO responses to illness behavior were predictive of greater fatigue-related severity and bodily pain. Solicitous SO responses to fatigue behavior were particularly influential in the context of a satisfactory relationship. In highly satisfactory relationships, solicitous SO responses were associated with significantly greater fatigue severity and fatigue-related disability than in relationships characterized by low or average satisfaction. CONCLUSIONS: Solicitous SO responses to CFS-related symptoms are associated with poorer patient outcomes, especially in the context of a satisfactory intimate relationship. Because of the cross-sectional nature of the study, the direction of effects cannot be interpreted unambiguously. SOs may be inadvertently positively reinforcing illness-related behavior: Solicitous partners may help the patient more with tasks of daily living, thereby decreasing the patient's activity level, which may lead to deconditioning and disability. Alternatively, patients with more severe symptoms and disability may present more opportunities for concerned SO responses, which again may be heightened in the context of a caring, satisfactory relationship. In either case, the results suggest that additional research on the role of solicitous SO responses is warranted.

Adult↗
PubMed2002

A predictive fatigue model--II: Predicting the effect of resting times on fatigue.

We have recently developed a force- and fatigue-model system that accurately predicted the effect of stimulation frequency on muscle fatigue. The data used to test the model were produced by stimulation trains with resting times of 500 ms. Because the resting times between stimulation trains affect muscle fatigue, this study tested the model's ability to predict the effect of resting times on fatigue. In addition, because this study included different subjects than those used to develop the model, the validity of the model could be tested. Data were collected from human quadriceps femoris muscles using fatigue protocols that included resting times of 500, 750, or 1000 ms. Our results showed that the model predicted fatigue as being a decreasing function of resting time, which was consistent with experimental data. Reliability tests between the experimental data and predictions showed interclass correlation coefficients of 0.97, 0.95, and 0.81 for the initial, final, and percentage decline in peak forces, respectively, suggesting strong agreement between the experimental data and the predictions by the model. The success of our current force- and fatigue-model system helps to validate the model and suggests its potential use in identifying the optimal activation pattern during clinical application of functional electrical stimulation.

Algorithms↗
PubMed2002

A comparison of patients with chronic fatigue syndrome attending separate fatigue clinics based in immunology and psychiatry.

Hospital clinics for patients with chronic unexplained fatigue are held in departments of various disciplines. This causes difficulties for referrers in choosing the appropriate clinic and for researchers in generalizing findings from one type of clinic to others. We randomly selected 37 outpatients attending an immunology fatigue clinic and 36 outpatients attending a psychiatry fatigue clinic, all of whom had chronic fatigue syndrome. We compared demographic factors, symptoms, disability, quality of life, psychological distress and illness attributions. The patients from the two clinics were closely similar in their specific symptoms, disability, quality of life, psychological distress and previous attendance to mental health professionals. Psychological distress was high and equal in the two samples. The proportion of men was greater among patients attending the immunology clinic. In a post-hoc analysis, 64% of immunology attenders attributed their fatigue to physical factors, compared with 31% of psychiatry clinic attenders (chi(2)=6.35, 1 d.f., P=0.01). These findings suggest that research data from one type of chronic fatigue clinic can be generalized to others. Clinically similar patients are referred to different clinics, and the choice of clinic may be influenced by the patients' illness beliefs. The high levels of emotional distress suggest that psychosocial management is as important as physical management in hospital outpatients with chronic fatigue syndrome, irrespective of its aetiology.

Adult↗
PubMed1993

Changes in relations between surface electromyogram and fatigue level by repeating fatiguing static contractions.

Changes in relations between surface electromyogram (EMG) and fatigue level estimated by fatigue sensation were studied during repeated fatiguing static contractions. Six male subjects performed elbow flexion of 13-15%MVC. Contractions were repeated 5 times (C1, C2, C3, C4, C5) with 5 min intervals of rests. The contractions continued until the onset of fatigue sensation such as obvious pain or considerable tiredness. Bipolar surface EMGs were recorded from 6 synergists of elbow flexors. Mean amplitude (AEMG) and relative power spectrum (RPW) of EMG were calculated. Partial correlation coefficients between time, AEMG, and RPW during each contraction were calculated. AEMG increased with time. EMG spectrum shifted towards lower frequencies with time. The correlations between AEMG and RPW were negative below 60Hz. AEMG and RPW were compared between C1 and C2-C5 being related with fatigue sensations. The changes in AEMG and EMG spectrum with the repeated contractions were similar to those with the development of fatigue. The increases in AEMG with the repeats were seen in most synergists in 4 subjects. Though EMG roughly reflected the fatigue during work, the changes of EMG were thought to include active adaptation to work.

Adult↗
PubMed1994

[Evaluation of physical exercise and fatigue sensation by CFSI (Cumulative Fatigue Symptoms Index)].

Cumulative Fatigue Symptoms Index (CFSI) is used for workers' subjective assessment of feeling of fatigue and of symptoms. Until now, this index has been used in the analysis of members of the same occupation. The purpose of this study is to examine fatigue symptoms in workers and to assess by CFSI the effect of regular physical exercise. Study participants were an exercise group (n = 67) and a non-exercise group (n = 115) of older workers, aged from 30 to 69 years. The CFSI questionnaire was distributed to all participants and the former group (exercise) answered two descriptive questions concerning the aim and subjective effects of physical exercise. As a result, it was found that mental fatigue symptoms decreased in the exercise group even after considering the differences in managerial position, subjective senses on health and marital status which are related to degree of feelings of fatigue. Weakened vitality was significantly less in the exercise group than the non-exercise group. Therefore, we concluded that weakened vitality would be needed to be regarded on an assessment scale for effects caused by exercise. It has also been considered that we should investigate general fatigue in assessing physical fatigue relating to one's lifestyle.

Adult↗
PubMed1997

The effects of preceded fatiguing on the relations between monopolar surface electromyogram and fatigue sensation.

Relations between surface electromyogram (EMG) and fatigue sensation was compared between the first fatiguing contraction and the following contractions with insufficient rests. Six male subjects performed static contractions of the elbow flexors at 8 and 13% MVC with the forearm semipronated and at 13% MVC with the forearm supinated. Contractions were repeated 6 (13% MVC) or (8% MVC) times (C1, C2, C3, C4, C5, C6) with rests of 5 min (13% MVC) or 10 min (8% MVC). During the contractions the subjects reported values of rated fatigue sensation (VRFS) whose scale was from 0.0 (no fatigue sensation) to 4.0 (apparent pain and moderate severity) at every 30 sec. C1 ended between 3.5 and 4.0 of VRFS or at 18 min (13% MVC) or 20 min (8% MVC) of contracting time. C2-C5 ended when fatigue sensation became that at the end of C1 or 5 min had passed. Bipolar and monopolar surface EMG was recorded from 6 synergists of elbow flexors. Mean amplitude (AEMG) and relative power below 22Hz (RPWL20) were calculated. Though AEMGs were positively correlated with VRFSs in C1, the correlations were often obscure in C2-C6. Most AEMGs at the same VRFS were larger in C2-C6 than in C1. AEMGs at the start of C2-C6 were sometimes larger than those at the end of C1. RPWL20s of monopolar EMG positively correlated with VRFSs. The RPWL20 correlations were often reserved in all contractions. The increases of AEMGs in C2-C6 at the same VRFS cannot be explained by the migration of the activities among synergists, since the increases in AEMGs were seen in most synergists simultaneously. The compensation of the failure of muscle contractibility were not the only cause of the increases in the AEMGs during fatiguing contractions. The compression of EMG spectrum towards lower frequencies was usable to estimate the change of fatigue sensation.

Adult↗
PubMed2003

Levocarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue.

AIM: Levocarnitine is an important contributor to cellular energy metabolism. This study aims to evaluate the effects of levocarnitine supplementation on body composition, lipid profile and fatigue in elderly subjects with rapid muscle fatigue. METHOD: This was a placebo-controlled, randomised, double-blind, two-phase study. Eighty-four elderly subjects with onset of fatigue following slight physical activity were recruited to the study. Prior to randomisation all patients entered a 2-week normalisation phase where they were given an 'ad libitum'diet, according to the National Cholesterol Education Program (Step 2). Subjects were asked to record their daily food intake every 2 days. Before the 30-day treatment phase, subjects were randomly assigned to two groups (matched for male/female ratio, age and body mass index). One group received levocarnitine 2g twice daily (n = 42) and the other placebo (n = 42). Efficacy measures included changes in total fat mass, total muscle mass, serum triglyceride, total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), apolipoprotein (apo)A1, and apoB levels. The Wessely and Powell scale was used to evaluate physical and mental fatigue. Subjects were assessed at the beginning and end of the study period. RESULTS: At the end of the study, compared with placebo, the levocarnitine-treated patients showed significant improvements in the following parameters: total fat mass (-3.1 vs -0.5 kg), total muscle mass (+2.1 vs +0.2 kg), total cholesterol (-1.2 vs +0.1 mmol/L), LDL-C (-1.1 vs -0.2 mmol/L), HDL-C (+0.2 vs +0.01 mmol/L), triglycerides (-0.3 vs 0.0 mmol/L), apoA1 (-0.2 vs 0.0 g/L), and apoB (-0.3 vs -0.1 g/L). Wessely and Powell scores decreased significantly by 40% (physical fatigue) and 45% (mental fatigue) in subjects taking levocarnitine, compared with 11% and 8%, respectively, in the placebo group (p < 0.001 vs placebo for both parameters). No adverse events were reported in any treatment group. CONCLUSION: Administration of levocarnitine to healthy elderly subjects resulted in a reduction of total fat mass, an increase of total muscle mass, and appeared to exert a favourable effect on fatigue and serum lipids.

Aged↗
PubMed2004

[Studies on the non-fatigue specificity of the fatigue-related sEMG signal parameters].

OBJECTIVE: To investigate the non-fatigue specificity of the changes of the fatigue-related parameters of sEMG signal during muscle static contractions. METHOD: The sEMG signals of biceps brachii (BB) and triceps brachii (TB) were recorded in 10 subjects during 1 min sustained right elbow isometric flexion. Changes of a series of fatigue-related indices such as MPF, MF, ZCR, AEMG and Lempel-ziv complexity were then analyzed. MVCs of the extensor (TB) were measured before and immediately after fatiguing flexion. RESULT: MPF, MF, ZCR and Lempel-ziv complexity of BB all decreased regularly and linearly with continuation of contraction. Whereas AEMG of BB increased linearly. The MVCs of TB were (14.0 +/- 3.2)kg and (14.6 +/- 2.6)kg respectively before and after BB fatiguing contraction. But the slopes of decrease of MPF, MF, ZCR and Lempel-ziv complexity of TB were significantly steeper than those of BB. The AEMG of TB was almost unchanged. CONCLUSION: The changes of time- and frequency-domain indices and Lempel-ziv complexity of sEMG signal were not as a result of muscle fatigue specifically. Fatigue might not be the only factor that caused the changes of the indices mentioned above.

Adult↗
PubMed2000

Fatigue characterization of a hydroxyapatite-reinforced polyethylene composite. II. Biaxial fatigue.

Previously, the uniaxial fatigue behavior of 40 volume % hydroxyapatite-reinforced polyethylene composite (HAPEXtrade mark) at 37 degrees C in saline was studied. Fatigue limits between 37 and 25% of the ultimate strengths of the material were established. This study investigates the biaxial fatigue behavior of the same material using various combinations of axial and torsional stresses. The addition of torsional to axial loading significantly reduced the fatigue life. When torsion at 25% of the ultimate strength was applied in addition to axial loading at 25% of the ultimate tensile strength, the fatigue life remained more than 1 million cycles. Out-of-phase loading was less detrimental to the fatigue life of the composite than in-phase. Fatigue damage was monitored by hysteresis loops, the increase in dissipated energy, the reduction in tangent modulus, and the increase in strain values.

Biocompatible Materials↗
PubMed1978

Metabolic correlates of fatigue and of recovery from fatigue in single frog muscle fibers.

Fatigue and recovery from fatigue were related to metabolism in single fibers of the frog semitendinosus muscle. The fibers were held at a sarcomere length of 2.3 microm in oxygenated Ringer solution at 15 degrees C and were stimulated for up to 150 s by a schedule of 10-s, 20-Hz tetanic trains that were interrupted by 1-s rest periods, after which they were rapidly frozen for biochemical analysis. Two kinds of fatigue were produced in relation to stimulus duration. A rapidly reversed fatigue occurred with stimulation for under 40 s and was evidenced by a decline in tetanic tension that could be overcome by 1 s of rest. A prolonged fatigue was caused by stimulation for 100-150 s. It was evidenced during stimulation by a fall in tetanic tension that could not be overcome by 1 s of rest, and after stimulation by a reduction, lasting for up to 82 min, in the peak tension of a 200-ms test tetanus. Fiber phosphocreatine (PCr) fell logarithmically in relation to stimulus duration, from a mean of 121 +/- 8 nmol/mg protein (SEM, n = 12) to 10% of this value after 150 s of stimulation. PCr returned to normal levels after 90-120 min of rest. Stimulation for 150 s did not significantly affect fiber glycogen and reduced fiber ATP by at most 15%. It is suggested that the prolonged fatigue caused by 100-150 s of tetanic stimulation was caused by long-lasting failure of excitation-contraction coupling, as it was not accompanied by depletion of energy stores in the form of ATP. One possibility is that H+ accumulated in fatigued fibers so as to interfere with the action of Ca2+ in the coupling process.

Adenosine Triphosphate↗