Severe fatigue is highly prevalent in ALL rheumatic diseases: an international study

Background Fatigue is a common, disabling, and difficult to manage problem in rheumatic diseases. Prevalence estimates of fatigue within various rheumatic disease groups vary considerably. Data on the relative prevalence of severe fatigue across multiple rheumatic diseases using a similar instrument is missing. Objectives The aim of this study was to provide an overview of the prevalence of severe fatigue across a broad range of rheumatic diseases and to examine its relationship with clinical and demographic variables. Methods Online questionnaires were filled out by an international sample of 6120 patients (88% female, mean age 47) encompassing 30 different rheumatic diseases. Fatigue was measured with the RAND(SF)-36 Vitality scale. A score of ≤35 was taken as representing severe fatigue. This cut-off score is similar to the 10th percentile of the general population; it was found to have 90% sensitivity (90% of people with chronic fatigue syndrome according to established classification criteria was correctly identified as having chronic fatigue syndrome using this cut-off score) and 81% specificity (81% of the people not having chronic fatigue syndrome according to established classification criteria was correctly identified as not having chronic fatigue syndrome using this cut-off score). Results Severe fatigue was present in 41% to 57% of the patients with a single inflammatory rheumatic disease such as rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, Sjögren's syndrome, psoriatic arthritis, and scleroderma. The percentage of patients with severe fatigue was 59% in patients with multiple rheumatic diseases without fibromyalgia. Severe fatigue was least prevalent in patients with osteoarthritis (35%) and most prevalent in patients with (comorbid) fibromyalgia (around 80%). In logistic regression analysis, severe fatigue was predicted by having (comorbid) fibromyalgia, having multiple rheumatic diseases without fibromyalgia, younger age, lower education, and linguistic background. Of Dutch, English, French, German, Portuguese and Spanish speaking patients, severe fatigue was most prevalent in French speaking patients and least prevalent in Dutch speaking patients. Conclusions Severe fatigue is very common in all rheumatic diseases. Our study indicates that about one out of every two patients with a rheumatic disease is severely fatigued. As severe fatigue can have devastating effects for the patient, the near environment, and society at large, unraveling the underlying mechanisms of fatigue and developing optimal treatment strategies should be top priorities in rheumatological research and practice. Acknowledgements Thanks to Isabel Lόpez-Chicheri García (Murcia, Spain), Ricarda Mewes & Winfried Rief (Marburg, Germany), Karoline Vangronsveld & Geert Crombez (Ghent, Belgium), Andreas AJ Wismeijer, Henriët van Middendorp & Johannes WJ Bijlsma (Tilburg & Utrecht, the Netherlands), and Mark A Lumley (Detroit, USA) for help in data collection.