Aim: To determine whether persistent severe fatigue in patients with rheumatoid arthritis can be predicted by inflammation and disability.
Methods: A follow-up study with a one-year duration was performed. From an existing rheumatoid arthritis cohort, 150 consecutive patients, with established rheumatoid arthritis, were asked to assess fatigue, using the subscale Checklist Individual Strength-fatigue of the Checklist Individual Strength at baseline and 12 months later. The Checklist Individual Strength-fatigue scores were classified into 'normal' (score between 8-27), 'moderate' (score between 27-34) or 'severe' (score 35 or above) fatigue. Disease-related variables were: tender joints, swollen joints, general health, disability and laboratory measures (erythrocyte sedimentation rate, rheumatoid factor and haemoglobin). Predictors of persistent severe fatigue were identified by multiple logistic regression analyses with backward selection (selection criteria: p<0.05).
Results: At baseline, 137 patients agreed to participate and 123 patients completed the study. Severe fatigue was experienced by as many as 50% of the patients, both at baseline and at the end of the study (n = 123). Moreover, 49 patients (40%) experienced severe fatigue at baseline as well as at follow-up, which we called 'persistent severe fatigue'. Persistent severe fatigue was predicted by mean general health and disability at baseline [odds ratio (OR) = 2.03 and 2.83, respectively] in this group of rheumatoid arthritis patients with a low-to-moderate level of disease activity and disability.
Conclusion: The data show that severe fatigue is not resolved spontaneously in rheumatoid arthritis patients, and persistent severe fatigue is mainly predicted by general health and disability. The relation with inflammation or a low level of haemoglobin, which is often assumed in clinical practice, was not found.
Relevance to clinical practice: Fatigue in patients with rheumatoid arthritis has to be considered as a symptom that needs to be addressed by professionals in the same way as pain and disability. In current care, fatigue is insufficiently addressed.