Assessment of Fatigue in Spondyloarthritis and Its Association with Disease Activity

To evaluate fatigue in patients with spondyloarthritis (SpA) and to define its association with disease-related factors and patients' features.

A cross-sectional multicenter study which includes 2251 patients with SpA selected from the national Spondyloarthropathies Registry (the Spanish Society of Rheumatology; REGISPONSER) Spanish cohort. The primary outcome was the assessment of fatigue performed with the first item of the Bath Ankylosing Spondyloarthritis Disease Activity Index followed by the study of its relation with different factors organized into 4 groups: sociodemographics, emotional, disease-related, and disease activity. Univariate logistic regressions, multivariate logistic regression, and multiple linear regressions were performed to relate fatigue with the studied covariates.

Mean fatigue score in all patients with SpA was 4.3 ± 2.9, with statistically significant differences between different SpA types. In univariate logistic regressions, significant differences were seen for many variables included in the 4 groups. Multivariate logistic regression showed that high fatigue score was related with sex (female), emotional component, the Ankylosing Spondylitis Quality of Life score, stiffness, and high levels of 2 visual analog scale items (vertebral pain in the last week and patient's global assessment of disease activity). The multivariate linear regression showed that fatigue was mainly explained by disease-related factors and disease activity (54.1%), but sex and emotional status may also be involved in 13.5% of the variance.

Fatigue is associated with disease-related factors and mostly with SpA activity. However, the emotional component and sex may contribute to the onset of fatigue.