Fatigue in psoriasis: a phenomenon to be explored

Summary Fatigue is a prevalent and substantial phenomenon in many patients with chronic inflammatory diseases, often rated by patients as the most troublesome symptom and aspect of their disease. It frequently interferes with physical and social functions and may lead to social withdrawal, long‐standing sick leave and disability. Although psychological and somatic factors such as depression, sleep disorders, pain and anaemia influence fatigue, the underlying pathophysiological mechanisms by which fatigue is generated and regulated are largely unknown. Increasing evidence points towards a genetic and molecular basis for fatigue as part of the innate immune system and cellular stress responses. Few studies have focused on fatigue in dermatological diseases. Most of these studies describe fatigue as a phenomenon related to psoriatic arthritis and describe the beneficial effects of biological agents on fatigue observed in clinical studies. It is therefore possible that this problem has been underestimated and deserves more attention in the dermatological community. In this review, we provide a definition and explanation for chronic fatigue, describe some commonly used instruments for measuring fatigue, and present hypothetical biological mechanisms with an emphasis on activation of the innate immune system and oxidative stress. An overview of relevant clinical studies covering the theme ‘psoriasis and fatigue’ is given. What's already known about this topic? Fatigue is prevalent in patients with chronic inflammatory diseases, cancer and some neurological diseases. Depression, sleep disorders and pain influence fatigue. Genes and molecular signalling pathways are increasingly recognized as important contributors to fatigue. What does this study add? The relationship of fatigue with psoriasis disease activity is unclear. Biological drugs have a beneficial effect on fatigue in patients with psoriasis. More knowledge regarding the prevalence, severity and impact of fatigue in patients with psoriasis is needed. Future therapeutic studies should include fatigue as an outcome variable.