Fatigue is an almost universal patient complaint, yet it is infrequently addressed by the treating physician. A graded exercise program combined with cognitive behavioral therapy and appropriate medications appears to be the most efficacious approach.
Fatigue is a universally shared experience and a significant component of rheumatologic diseases. The fact that rheumatologic patients experience fatigue that negatively affects their quality of life has been well documented. What is less clearly understood are the multifactorial physical and emotional mechanisms that contribute to this fatigue and, as a result, limit effective treatment strategies, which to date still remain mostly empiric. Fatigue is often rated by patients with rheumatologic disease as one of the key factors leading to decreased quality of life. Fatigue is poorly correlated with the severity of disease. Despite the omnipresence of and the stress caused by fatigue, it is surprising how infrequently it is addressed by both patients and physicians. Rheumatologic patients often believe that fatigue is an expected part of the disease process or a side effect of medications. Physicians, however, either dismiss the fatigue as functional in origin or focus more on joint and muscle involvement or abnormal laboratory values.
Definition
There are many definitions of fatigue offered in the medical literature. However, for the purpose of discussing rheumatologic disease, a more global, biopsychosocial orientation is applied. As quoted in the Physiologic Basis of Rehabilitation Medicine , Dill offered the following definition: “The various unmistakably disagreeable sensations commonly referred to the word fatigue are in fact the accompaniment of a great variety of physiologic conditions, which have in common only this, that the physiologic equilibrium of the body is breaking down.” A distinction should also be made between fatigue and fatigability, the latter being defined as progressive weakness of muscle with repetitive use followed by recovery after a brief period of rest. Fatigability has also remained underdiagnosed and may be an additional component of the global picture of fatigue in rheumatologic disorders.
Despite the pervasive and negative impact that fatigue can have on quality-of-life issues in the patient with rheumatologic disease, it does serve an important function as the body’s “warning signal,” forcing an individual to stop what he is doing and evaluate what is wrong.
This article reviews fatigue as it occurs in 4 common rheumatologic disorders: fibromyalgia syndrome (FMS), chronic fatigue syndrome (CFS), rheumatoid arthritis (RA), and osteoarthritis (OA).
Assessment of fatigue
History
Despite the significant negative impact fatigue imposes on the rheumatologic patient, it is often not addressed in clinical settings. Wolfe and Pincus reported that 89.7% of rheumatologists do not usually assess fatigue in their offices, and fewer than 15% collect any formal quantitative information regarding fatigue, psychological distress, and functional disability. Patient self-report questionnaires have been found to be a valuable tool in assessing fatigue and monitoring functional status. Wolfe and colleagues advocated the routine use of questionnaires as an integral part of patient care, which correlated with traditional measures, such as laboratory tests and radiographs. Moreover, questionnaires can be more effective in predicting long-term mortality and morbidity than measurements such as grip strength, walk time, or joint count. Multidimensional health status questionnaires such as Modified Health Assessment Questionnaire and Health Assessment Questionnaire (HAQ) have both been shown to be strong predictors of mortality in rheumatologic diseases. In 1 study involving 7760 patients, Wolfe showed that a single question asking patients to rate their fatigue in the past week on the visual analog scale (VAS) performed as well as 3 other significantly longer questionnaires. The single-item VAS fatigue scale was even more sensitive in detecting change in fatigue level than longer questionnaires. To use patient questionnaire effectively, it should be administered to all patients attending the clinic on a sequential basis.
A large number of fatigue scales exist, and there is no consensus on which fatigue-measuring scales are most appropriate for use in assessment of fatigue in rheumatologic disease. Fatigue is multidimensional in expression, with influence on physical, emotional, cognitive, and even social aspects of life. This created a challenge in its measurement. Many recent articles have focused on a questionnaire called functional assessment of chronic illness therapy (FACIT). This instrument was initially employed to evaluate fatigue in anemia and cancer patients. Recent studies, however, have evaluated its efficacy in rheumatologic disease. The FACIT-fatigue is an abbreviated 13-item measure of fatigue that has showed good internal consistency in patients with RA when compared with other extensive scales ( Table 1 ).
| Below is a list of statements that other people with your illness have said are important. Please circle or mark 1 number per line to indicate your response as it applies to the past 7 days | |||||
| Not at all | A little bit | Somewhat | Quite a bit | Very much | |
| I feel fatigued. | 0 | 1 | 2 | 3 | 4 |
| I feel weak all over. | 0 | 1 | 2 | 3 | 4 |
| I feel listless (“washed out”). | 0 | 1 | 2 | 3 | 4 |
| I feel tired. | 0 | 1 | 2 | 3 | 4 |
| I have trouble starting things because I am tired. | 0 | 1 | 2 | 3 | 4 |
| I have trouble finishing things because I am tired. | 0 | 1 | 2 | 3 | 4 |
| I have energy. | 0 | 1 | 2 | 3 | 4 |
| I am able to do my usual activities. | 0 | 1 | 2 | 3 | 4 |
| I need to sleep during the day. | 0 | 1 | 2 | 3 | 4 |
| I am too tired to eat. | 0 | 1 | 2 | 3 | 4 |
| I need help doing my usual activities. | 0 | 1 | 2 | 3 | 4 |
| I am frustrated by being too tired to do the things I want to do. | 0 | 1 | 2 | 3 | 4 |
| I have to limit my social activity because I am tired. | 0 | 1 | 2 | 3 | 4 |
This scale is easy to administer, patient-friendly, and provides reliable insights into the causes of fatigue. It can be easily adapted to other rheumatologic diseases such as fibromyalgia and OA.
Physical Examination
Fatigue is frequently not addressed in physical examinations during routine office visits, primarily due to its complex physiologic and psychosocial nature. To better delineate the objective physical manifestation of fatigue, the term fatigability has been used, which is defined as diminished strength as exercise of muscle groups proceeds. Experimental studies that test for fatigability have employed dynamometer, electrical stimulation of peripheral nerves, and transcranial magnetic stimulations. In routine clinical settings, fatigability can be assessed by manual muscle testing after repetitive movement of functionally important muscles. Dobkin offered the following approach:
The examiner could choose 10 to 15 repetitions of (1) raising the extended arms overhead or reaching and lifting an item, followed by retesting the strength of the isolated deltoids at 60° of abduction; (2) repetitive extension of the fingers against the modest resistance of an examiner’s finger; (3) repetitive 30° hip flexor movements with the patient supine and leg extended at the knee followed by retesting strength of the iliopsoas at 20° of hip flexion; (4) repetitive 20° hip extensor movements against gravity or a modest force with the patient prone; (5) repetitive 60° knee flexor movements while prone against only gravity or modest resistance, followed by retesting the hamstrings with the knee flexed 30°, and so on. Retesting that reveals any decline from the initial torque and that resolves after a minute of rest would be consistent with exercise-induced fatigability.
Laboratory tests are not routinely used for the monitoring of fatigue, since fatigue has been found to correlate with pain and depression and not with disease activity as reflected by laboratory tests such as erythrocyte sedimentation rate or rheumatoid factor.
Assessment of fatigue
History
Despite the significant negative impact fatigue imposes on the rheumatologic patient, it is often not addressed in clinical settings. Wolfe and Pincus reported that 89.7% of rheumatologists do not usually assess fatigue in their offices, and fewer than 15% collect any formal quantitative information regarding fatigue, psychological distress, and functional disability. Patient self-report questionnaires have been found to be a valuable tool in assessing fatigue and monitoring functional status. Wolfe and colleagues advocated the routine use of questionnaires as an integral part of patient care, which correlated with traditional measures, such as laboratory tests and radiographs. Moreover, questionnaires can be more effective in predicting long-term mortality and morbidity than measurements such as grip strength, walk time, or joint count. Multidimensional health status questionnaires such as Modified Health Assessment Questionnaire and Health Assessment Questionnaire (HAQ) have both been shown to be strong predictors of mortality in rheumatologic diseases. In 1 study involving 7760 patients, Wolfe showed that a single question asking patients to rate their fatigue in the past week on the visual analog scale (VAS) performed as well as 3 other significantly longer questionnaires. The single-item VAS fatigue scale was even more sensitive in detecting change in fatigue level than longer questionnaires. To use patient questionnaire effectively, it should be administered to all patients attending the clinic on a sequential basis.
A large number of fatigue scales exist, and there is no consensus on which fatigue-measuring scales are most appropriate for use in assessment of fatigue in rheumatologic disease. Fatigue is multidimensional in expression, with influence on physical, emotional, cognitive, and even social aspects of life. This created a challenge in its measurement. Many recent articles have focused on a questionnaire called functional assessment of chronic illness therapy (FACIT). This instrument was initially employed to evaluate fatigue in anemia and cancer patients. Recent studies, however, have evaluated its efficacy in rheumatologic disease. The FACIT-fatigue is an abbreviated 13-item measure of fatigue that has showed good internal consistency in patients with RA when compared with other extensive scales ( Table 1 ).
| Below is a list of statements that other people with your illness have said are important. Please circle or mark 1 number per line to indicate your response as it applies to the past 7 days | |||||
| Not at all | A little bit | Somewhat | Quite a bit | Very much | |
| I feel fatigued. | 0 | 1 | 2 | 3 | 4 |
| I feel weak all over. | 0 | 1 | 2 | 3 | 4 |
| I feel listless (“washed out”). | 0 | 1 | 2 | 3 | 4 |
| I feel tired. | 0 | 1 | 2 | 3 | 4 |
| I have trouble starting things because I am tired. | 0 | 1 | 2 | 3 | 4 |
| I have trouble finishing things because I am tired. | 0 | 1 | 2 | 3 | 4 |
| I have energy. | 0 | 1 | 2 | 3 | 4 |
| I am able to do my usual activities. | 0 | 1 | 2 | 3 | 4 |
| I need to sleep during the day. | 0 | 1 | 2 | 3 | 4 |
| I am too tired to eat. | 0 | 1 | 2 | 3 | 4 |
| I need help doing my usual activities. | 0 | 1 | 2 | 3 | 4 |
| I am frustrated by being too tired to do the things I want to do. | 0 | 1 | 2 | 3 | 4 |
| I have to limit my social activity because I am tired. | 0 | 1 | 2 | 3 | 4 |
This scale is easy to administer, patient-friendly, and provides reliable insights into the causes of fatigue. It can be easily adapted to other rheumatologic diseases such as fibromyalgia and OA.
Physical Examination
Fatigue is frequently not addressed in physical examinations during routine office visits, primarily due to its complex physiologic and psychosocial nature. To better delineate the objective physical manifestation of fatigue, the term fatigability has been used, which is defined as diminished strength as exercise of muscle groups proceeds. Experimental studies that test for fatigability have employed dynamometer, electrical stimulation of peripheral nerves, and transcranial magnetic stimulations. In routine clinical settings, fatigability can be assessed by manual muscle testing after repetitive movement of functionally important muscles. Dobkin offered the following approach:
The examiner could choose 10 to 15 repetitions of (1) raising the extended arms overhead or reaching and lifting an item, followed by retesting the strength of the isolated deltoids at 60° of abduction; (2) repetitive extension of the fingers against the modest resistance of an examiner’s finger; (3) repetitive 30° hip flexor movements with the patient supine and leg extended at the knee followed by retesting strength of the iliopsoas at 20° of hip flexion; (4) repetitive 20° hip extensor movements against gravity or a modest force with the patient prone; (5) repetitive 60° knee flexor movements while prone against only gravity or modest resistance, followed by retesting the hamstrings with the knee flexed 30°, and so on. Retesting that reveals any decline from the initial torque and that resolves after a minute of rest would be consistent with exercise-induced fatigability.
Laboratory tests are not routinely used for the monitoring of fatigue, since fatigue has been found to correlate with pain and depression and not with disease activity as reflected by laboratory tests such as erythrocyte sedimentation rate or rheumatoid factor.
Fatigue in fibromyalgia
Perhaps no rheumatologic disorder is more associated with fatigue than FMS, the most common widespread pain disorder in the United States. Fibromyalgia affects 2% of 4% of the general population, and between 76% and 81% of people with fibromyalgia suffer from the symptom of chronic fatigue. FMS is a syndrome without known pathologic agents, whose cardinal symptoms include pain, fatigue, and nonrestorative sleep. Specific criteria for the diagnosis of FMS were established in 1990 by the American College of Rheumatology (ACR) [ Table 2 ].
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Pain and Fatigue
Although a distinct cause for FMS is unknown, the most commonly accepted theories include the following: (1) central sensitization, with dysfunctional processing of pain by the central nervous system, (2) suppression of descending inhibitory pain pathways, (3) various neurohumoral dysregulations, especially those involving serotonin, norepinephrine, and substance P, (4) suppression and dysregulation of the hypothalamic-pituitary-adrenal axis. Regardless of the pathologic mechanism(s), the result is widespread body pain, which, in turn, is closely associated with overwhelming fatigue. Common patient complaints often reflect this inter-relationship between pain and fatigue, for example, “The pain wears me down” or “When I’m tired I hurt all over.” Fibromyalgia patients often describe the fatigue as overwhelming, exhaustive, debilitating, or incapacitating. Patients literally describe having to stop what they are doing and lie down. Wolfe and Pincus in a study in Rheumatology 1999 noted that in multivariate analysis, the strongest independent predictors for fatigue were pain, sleep disturbance, depression, tender point count, and HAQ. In a 2007 study, pain was confirmed as among the strongest predictors of fatigue: “Individuals with higher average level of pain reported greater fatigue and daily increase in pain were related to daily increase in fatigue, including elevation of fatigue on the next day.” A 2008 workshop sponsored by the National Institute of Aging noted that physical functioning in FMS, RA, and OA was predicted by pain and fatigue but not by pain alone.
Nonrestorative Sleep and Fatigue
Nonrestorative, fragmented sleep is a constituent of the fibromyalgia syndrome and a significant contributor to the fatigue experienced by the fibromyalgia patient. Nearly all patients suffering from FMS experience poor sleep quality, and the fatigue that follows is so pervasive that half of the patients who meet ACR criteria for FS also meet criteria for CFS. Fibromyalgia patients were also reported to have higher stress responses to a variety of stimuli, which in turn compromise sleep and in turn exacerbate fatigue.
Mental Fatigue (“Fibrofog”)
Cognitive deficits involving memory and mental clarity referred to as “fibrofog” are common in FMS. However, formal cognitive testing often does not support deterioration. FMS patients can experience dissociation or disengagement, which refers to the separation of parts of experience from the mainstream of consciousness. A common example is highway hypnosis.
Evaluating Fatigue in Fibromyalgia
In evaluating fatigue in the fibromyalgia patient, there is a temptation to ascribe fatigue to the disease itself, rather than looking for alternative causes. Although no longer considered a diagnosis of exclusion, many conditions can mimic and occur concurrently with FMS and produce significant fatigue ( Table 3 ).
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