Assessment of fatigue in rheumatoid arthritis and its relation to pain and disease activity measures

Abstract

Background Fatigue is a serious outcome of rheumatoid arthritis (RA). Inflammatory synovitis is potentially an important causal factor for RA fatigue. Other factors include psychosocial factors, health beliefs, illness perceptions, and poor social support. Fatigue also has strong relationships to pain and depression. Objective The aim of the study was to define the amount of fatigue experienced by RA patients, and determine the relative contribution of RA disease activity to fatigue in comparison with factors such as pain and treatment in established RA cases using different instruments to assess fatigue [visual analog scale (VAS) fatigue and the vitality subscale of the Medical Outcomes Study Short Form 36 (SF-36) questionnaire]. Patients and methods A total of 50 adult patients diagnosed with RA according to the 1987 Revised American College of Rheumatology - 42 of them being female and the remaining eight being male, with a mean age of 45.36 ± 9.6 years and a mean disease duration of 7.78 ± 4.1 years - were included in the study. Fatigue was measured using a 100 mm VAS and the SF-36 vitality scores. We measured pain using 100 mm VAS, Disease Activity Score for 28 joint counts (DAS28), early morning stiffness, the modified Health Assessment Questionnaire score, and the physician global assessment score. Results Fatigue was common in RA patients. Out of 50 patients, 42 patients had fatigue (VAS ≥ 20 mm), and at the same time 26 had high fatigue scores (VAS΃50 mm). The mean SF-36 energy and vitality score was 60.5 ± 23.1. The VAS fatigue scores and the SF-36 vitality scores were significantly correlated with disease activity measures, including duration of morning stiffness (P = 0.001), articular index (P < 0.0001), VAS pain (P < 0.0001), DAS28 (P < 0.0001), C reactive protein (CRP) (P = 0.04 and 0.001, respectively), erythrocyte sedimentation rate (ESR) (P = 0.04), and rheumatoid factor positivity (P = 0.04 and 0.01, respectively). Pain had the strongest association with fatigue, followed by articular index, duration of morning stiffness, ESR, DAS28, and finally CRP in that order. Conclusion High fatigue levels are common in RA and are mainly linked to pain. VAS fatigue scores are simple measurements that can be used for assessment of fatigue in patients with RA.

Keywords

• fatigue, Medical Outcomes Study Short Form 36 vitality scores, rheumatoid arthritis, visual analog scale fatigue