Fatigue is a common, disabling, and difficult-to-manage problem in rheumatic diseases. Prevalence estimates of fatigue within rheumatic diseases vary considerably. Data on the prevalence of severe fatigue across multiple rheumatic diseases using a similar instrument is missing. Our aim was to provide an overview of the prevalence of severe fatigue across a broad range of rheumatic diseases and to examine its association with clinical and demographic variables. 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 (90 % sensitivity and 81 % specificity for chronic fatigue syndrome). Severe fatigue was present in 41 to 57 % of patients with a single inflammatory rheumatic disease such as rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, Sjögren’s syndrome, psoriatic arthritis, and scleroderma. Severe fatigue was least prevalent in patients with osteoarthritis (35 %) and most prevalent in patients with fibromyalgia (82 %). In logistic regression analysis, severe fatigue was associated with having fibromyalgia, having multiple rheumatic diseases without fibromyalgia, younger age, lower education, and language (French: highest prevalence; Dutch: lowest prevalence). In conclusion, one out of every two patients with a rheumatic disease is severely fatigued. As severe fatigue is detrimental to the patient, the near environment, and society at large, unraveling the underlying mechanisms of fatigue and developing optimal treatment should be top priorities in rheumatologic research and practice.

Objective. Patients with fibromyalgia have difficulty with the invisibility and medically unexplained character of the syndrome. Disbelief, lack of acceptance, and stigmatization by their spouse, family, colleagues, the health care system, and society are key issues in their lives. Nevertheless, the components of this phenomenon that we term "invalidation" are not clear. The aim of our study was to identify the definition and structure of invalidation as perceived by patients with fibromyalgia. Methods. A hierarchical cluster analysis was applied to examine everyday invalidation experiences of patients with fibromyalgia. Ninety-four statements about invalidation that were derived from interviews and a card-sorting (Q-sort) technique provided the input for this cluster analysis. Results. The hierarchical structure of invalidation showed a higher-order distinction between statements reflecting "discounting" and "understanding." Discounting was subdivided into the components "denying" and "patronizing" (consisting of "lecturing" and "overprotecting"). Understanding was subdivided into "supporting" and "acknowledging." These higher-order constructs were further subdivided into 15 lower-order clusters that reflected cognitive, affective, and behavioral aspects of invalidation. Conclusion. Invalidation as perceived by patients with fibromyalgia includes active negative social responses (denying, lecturing, and overprotecting) as well as a lack of positive social responses (supporting and acknowledging) with respect to the patient and the condition of the patient. This definition of invalidation provides a basis to quantify invalidation and to study its impact on symptom severity, quality of life, therapy adherence, therapy outcome, and other important aspects of fibromyalgia.

The 3*I is a brief, reliable instrument for assessing patients' perceptions of invalidation from different sources, which differ between patient groups and are associated with health status. Future validation research should clarify the clinical impact of invalidation on treatment adherence and outcome.

This study examined whether social support and invalidation (lack of understanding and discounting by others) are differently associated with physical and mental health. Participants were 1455 patients with fibromyalgia, rheumatoid arthritis, ankylosing spondylitis, osteorarthritis, or another rheumatic disease. Participants completed online questionnaires. Social support correlated negatively with discounting responses of others (moderately) and lack of understanding (strongly). Both invalidation and social support were additively associated with patients’ mental health, but only discounting was significantly associated with patients’ physical health. This suggests that improving health of patients with rheumatic diseases requires the consideration of both social support and invalidation.

Rheumatic diseases affect about 20% of the population, leading to common symptoms such as joint problems, pain, fatigue, and stiffness. Loneliness is prevalent in individuals with rheumatic diseases. This could be due to not receiving social support and being stigmatized and invalidated, which might be most common in fibromyalgia, a rheumatic disease that lacks medical evidence. The aim of this study was to compare loneliness in distinct rheumatic diseases and to examine the association of loneliness with social support and invalidation. Participants were 927 patients with ankylosing spondylitis (n = 152), fibromyalgia (n = 341), osteoarthritis (n = 150), rheumatoid arthritis (n = 171), or systemic diseases (n = 113). They completed online questionnaires including an 11-point Likert scale assessing loneliness, the Illness Invalidation Inventory (3*1; Kool et al., 2010), and the Social Support Survey (SSS; De Boer, Wijker, Speelman, & De Haes, 1996; Sherbourne & Stewart, 1991). Patients with fibromyalgia experienced significantly more loneliness than patients with ankylosing spondylitis and patients with rheumatoid arthritis. Besides being younger, having lower education, and not working, in multiple regression analyses both lack of social support and invalidation were independently correlated with loneliness. This suggests that to decrease loneliness, therapeutic attention should be given to both increasing social support as well as decreasing invalidation in patients with rheumatic diseases, especially in patients with fibromyalgia.