Abstract

INTRODUCTIONMedically unexplained symptoms (MUS)1 are somatic and psychiatric dysfunctions that organic status cannot explain. Somatic symptoms perceived by patients with MUS range from headaches and dizziness to fatigue.2 Psychiatric symptoms, such as depression and anxious, are also associated with MUS.3 Patients with MUS frequently visit primary care facilities because they exhibit various symptoms.4 The clinical concept of MUS5 includes disease groups such as somatic symptomatology and functional body syndromes, which generally have lower quality of life, general functioning and family functioning compared with healthy individuals.6 However, medical personnel often avoid MUS because it is difficult to explain the mechanism of these symptoms occurring in patients through clinical examinations and tests.7 Then, about 20%–25% of MUS patients develop chronic symptoms, making treatment even more difficult.2Fatigue is also a common symptom in healthy individuals and is a nonspecific and subjective symptom. Therefore, medical personnel often underestimate fatigue.8 However, fatigue has been reported that the economic burden and social loss caused by fatigue are significant.9 For example, it has been reported that chronic fatigue can generate as much as $9 billion in economic losses in the year.10 Furthermore, chronic fatigue syndrome, also treated as one of the MUS, significantly reduces the quality of