Fatigue in rheumatoid arthritis: association with severity of pain, disease activity and functional status

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic symmetric polyarthritis causing progressive joint destruction and disability. Major patient complaints are pain, disability and fatigue. The aim of this study is to assess fatigue and its association with disease-specific variables (severity of pain, disease activity, and functional status) in patients with RA.

A total of 160 RA patients were included in the study. Fatigue was measured by using Fatigue Symptom Inventory (FSI). The quadrivariate Disease Activity Score-28 (DAS28) was used for evaluating disease activity and Health Assessment Questionnaire (HAQ) for determining functional status. Severity of pain was measured by using 10 cm Visual Analog Scale-Pain (VAS-pain).

Intensity items of FSI (most fatigue, least fatigue, average fatigue, current fatigue) were strongly correlated with DAS28, HAQ, and VAS pain (p=0.000). When the correlation coefficients were analyzed, current fatigue showed the highest correlation with VAS-pain (r: 0.96). This was followed by DAS28 and HAQ, respectively (r: 0.77 and 0.70) (p=0.000). Duration items of FSI (number of days fatigued, amount of time fatigued) were significantly correlated with DAS28, HAQ, and VAS pain (p=0.000). Also there were significant positive correlations between interference scale of FSI and DAS28, HAQ, and VAS-pain (r: 0.68, 0.61 and 0.67, respectively) (p=0.000). None of FSI subgroups showed statistically significant correlation with di­sease duration.

Fatigue is strongly associated with severity of pain, disease activity and functional status. Fatigue should be included in clinical practice and clinical trials as a RA outcome measure.