From the Guidelines
Fatigue evaluation should begin with a comprehensive medical history and physical examination to identify potential underlying causes, as recommended by the American Society of Clinical Oncology clinical practice guideline adaptation 1. When evaluating fatigue, it is essential to consider the onset, pattern, duration, and associated or alleviating factors, as well as the patient's current disease status and treatment history 1. The evaluation should also include an assessment of treatable contributing factors, such as:
- Comorbidities (e.g., cardiac dysfunction, endocrine dysfunction, pulmonary dysfunction, renal dysfunction, anemia, arthritis, neuromuscular complications, sleep disturbances, pain, emotional distress) 1
- Medications (consider persistent use of sleep aids, pain medications, or antiemetics) 1
- Alcohol/substance abuse 1
- Nutritional issues (including weight/caloric intake changes) 1
- Deconditioning 1 Laboratory testing should be considered based on the presence of other symptoms, onset, and severity of fatigue, and may include:
- Complete blood count with differential 1
- Comprehensive metabolic panel 1
- Endocrinologic evaluation (e.g., TSH) 1
- Inflammatory markers (e.g., ESR or CRP) 1 Mental health screening for depression and anxiety is also essential, as these conditions frequently manifest as fatigue 1. The clinical team must decide when referral to an appropriately trained professional (e.g., cardiologist, endocrinologist, mental health professional, internist) is needed 1.
From the FDA Drug Label
The criterial include either: 1) excessive sleepiness or insomnia, plus frequent episodes of impaired breathing during sleep, and associated features such as loud snoring, morning headaches and dry mouth upon awakening; or 2) excessive sleepiness or insomnia and polysomnography demonstrating one of the following: more than five obstructive apneas, each greater than 10 seconds in duration, per hour of sleep and one or more of the following: frequent arousals from sleep associated with the apneas, bradytachycardia, and arterial oxygen desaturation in association with the apneas In addition, for entry into these studies, all patients were required to have excessive sleepiness as demonstrated by a score ≥10 on the Epworth Sleepiness Scale (ESS), despite treatment with continuous positive airway pressure (CPAP).
The evaluation of fatigue in the provided drug label is indirectly related to the measurement of excessive sleepiness. The label mentions the use of the Epworth Sleepiness Scale (ESS) to demonstrate excessive sleepiness, with a score ≥10 indicating excessive sleepiness. However, it does not directly address the evaluation of fatigue. 2
From the Research
Fatigue Evaluation
- Fatigue is a common presenting symptom in primary care, negatively impacting work performance, family life, and social relationships 3.
- The differential diagnosis of fatigue includes lifestyle issues, physical conditions, mental disorders, and treatment side effects 3, 4.
- Fatigue can be classified as secondary to other medical conditions, physiologic, or chronic 3, 5.
Causes of Fatigue
- Sleep disorders and sleep-related disorders of breathing, depression, and excessive psychosocial stress are the most common causes of persistent fatigue 4.
- Previously undiagnosed cancer is a rare cause of fatigue, accounting for only 0.6% of cases 4.
- Anemia and other organic causes are also rare, accounting for 4.3% of cases 4.
Diagnosis and Management
- A comprehensive history and physical examination should focus on identifying common secondary causes and life-threatening problems 3, 5.
- Laboratory studies are only necessary in the presence of additional symptoms or findings, and repeat testing is generally not indicated if initial results are normal 3, 4.
- Treatment of fatigue should include a structured plan for regular physical activity, such as walking, and may also involve cognitive behavior therapy, exercise therapy, and acupuncture 3, 5.
- Patients with chronic fatigue may benefit from psychoeducative and psychotherapeutic approaches, as well as an individually adapted exercise program 4, 5.
Measurement of Fatigue
- Fatigue is a multidimensional construct that can be measured using validated clinical measures, such as the Multidimensional Fatigue Inventory 6.
- Physical fatigue is the most commonly assessed fatigue dimension, but other dimensions, such as cognitive and emotional fatigue, should also be considered 6.