Impact of fatigue on rheumatic diseases.

Fatigue is a common, disabling, and difficult-to-manage problem in rheumatic diseases. The concept of fatigue is difficult to define. No clear and widely accepted definition of fatigue is available. The symptoms of fatigue are defined as an overwhelming, debilitating, and sustained sense of exhaustion that decreases the ability to function and carry out daily activities. Prevalence estimates of fatigue within musculoskeletal diseases vary considerably (35%-82%). In this review, we present data about the role of fatigue for the patients' quality of life, tools for diagnosing fatigue, factors contributing to fatigue like disease activity and psychological factors, and some experimental studies to verify the biological background of fatigue. Management of fatigue including pharmacological and non-pharmacological treatment is also part of this publication. Overall data are scarce for fatigue in rheumatic diseases, and further studies are warranted to identify the role of biological mechanism such as inflammation, hormonal changes, and autonomic nervous system in the pathogenesis of fatigue.