ASAS Health Index in patients with spondyloarthritis and its association with disease activity and disease burden including fibromyalgia.

OBJECTIVES: To evaluate the association of the Assessment of Spondyloarthritis international Society Health Index (ASAS-HI) with disease activity and disease burden in patients with spondyloarthritis (SpA). METHODS: Observational, cross-sectional and single-centre study from the Córdoba AxSpA Task force, Registry and Outcomes (CASTRO). Scores related to disease activity (BASDAI and ASDAS), functionality (BASFI), structural damage, mobility, health and the presence of concomitant fibromyalgia (FM) were obtained from all patients. ASAS-HI score was considered the main outcome. Pearson's r statistic, Student's t test, and univariate and multivariate linear regressions were performed to assess the association between the ASAS-HI score and the studied covariates. RESULTS: A total of 126 SpA patients were included. The mean ASAS-HI score was 4.6±3.9, showing a "strong" positive linear correlation (r>0.60) with the BASDAI and BASFI and a "moderate" positive linear correlation (r=0.40 to 0.60) with the global VAS and ASDAS. Patients with FM showed a significantly higher ASAS-HI score than patients without FM (9.5±3.2 vs. 3.7±3.4, respectively, p<0.01). Multiple linear regression showed that 57.4% of the ASAS-HI variability (R2=0.574) was explained by the presence of concomitant FM (ß=2.23, 95% CI 0.73 to 3.80, p=0.004), higher scores on the BASDAI (ß=0.62, 95% CI 0.25 to 0.97, p=0.001) and BASFI (ß=0.57, 95% CI 0.26 to 0.88, p=0.001). CONCLUSIONS: The impairment of health in patients with SpA was mainly associated with high disease activity, worsening functionality and with the presence of a possible concomitant FM. Therefore, in patients with high ASAS-HI scores we must evaluate the presence of concomitant FM.

Complement component 3 as biomarker of disease activity and cardiometabolic risk factor in rheumatoid arthritis and spondyloarthritis.

OBJECTIVE: To analyze the relationship between complement component 3 (C3) and the prevalence of cardiometabolic risk factors and disease activity in the rheumatic diseases having the highest rates of cardiovascular morbidity and mortality: rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). METHODS: This is a cross-sectional study including 200 RA, 80 PsA, 150 axSpA patients and 100 healthy donors. The prevalence of cardiometabolic risk factors [obesity, insulin resistance, type 2 diabetes mellitus, hyperlipidemia, apolipoprotein B/apolipoprotein A (apoB/apoA) and atherogenic risks and hypertension] was analyzed. Serum complement C3 levels, inflammatory markers and disease activity were evaluated. Cluster analysis was performed to identify different phenotypes. Receiver operating characteristic (ROC) curve analysis to assess the accuracy of complement C3 as biomarker of insulin resistance and disease activity was carried out. RESULTS: Levels of complement C3, significantly elevated in RA, axSpA and PsA patients, were associated with the prevalence of cardiometabolic risk factors. Hard clustering analysis identified two distinctive phenotypes of patients depending on the complement C3 levels and insulin sensitivity state. Patients from cluster 1, characterized by high levels of complement C3 displayed increased prevalence of cardiometabolic risk factors and high disease activity. ROC curve analysis showed that non-obesity related complement C3 levels allowed to identify insulin resistant patients. CONCLUSIONS: Complement C3 is associated with the concomitant increased prevalence of cardiometabolic risk factors in rheumatoid arthritis and spondyloarthritis. Thus, complement C3 should be considered a useful marker of insulin resistance and disease activity in these rheumatic disorders.

Assessment of Fatigue in Spondyloarthritis and Its Association with Disease Activity.

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