Objective: To determine the prevalence of fatigue in rheumatic disease; to characterize the strength of associations between demographic and clinical features and fatigue; to identify predictors of fatigue, and to determine the consequence of clinically significant fatigue.
Methods: 1488 consecutive patients with rheumatic disease were assessed with the Clinical Health Assessment Questionnaire, a health status instrument with scales for fatigue, pain, global severity, sleep disturbance, gastrointestinal problems, anxiety, depression, health status, health satisfaction, and work ability. All patients underwent rheumatic disease examinations and laboratory testing.
Results: Fatigue measured by visual analog scale (VAS) was present in 88-98% of patients, but clinically important levels of fatigue (> or = 2.0 on VAS) were present in more than 41% of patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and 76% of those with fibromyalgia (FM). Fatigue was related to almost all demographic and clinical variables, but in multivariate analyses the strongest independent predictors of fatigue were pain, sleep disturbance, depression, tender point count and Health Assessment Questionnaire (HAQ) disability. About 90% of the R2 of the model (all patients = 0.51, RA = 0.49, OA = 0.45, FM = 0.41) was explained by pain, sleep disturbance, and depression. In RA assessed by erythrocyte sedimentation rate, joint count and grip strength, no association of the inflammatory process with fatigue could be found in the multivariate analyses. In measuring health status, fatigue was strongly associated with work dysfunction and general measures of health (VAS of global severity, health status, and health satisfaction).
Conclusion: Fatigue is common across all rheumatic diseases, associates with all measures of distress, and is a predictor of work dysfunction and overall health status. The correlates of fatigue are generally similar across RA, OA and FM. Fatigue assessment adds much to understanding and management of patients and diseases.