Ab0594 Multifactorial Explanatory Model of Fatigue in Patients With Rheumatoid Arthritis: A Structural Equation Approach

Background: Fatigue is an important and frequent comorbidity in patients with rheumatoid arthritis (RA), which can lead to significant impact upon the patient's quality of life (QoL). However, the mechanisms behind this association are poorly understood and its management is challenging. Objectives: We use a multifactorial explanatory model to assess the impact on fatigue of several parameters in patients with RA, including disease activity, perceived disease impact, haemoglobin levels, personality traits, depression and anxiety. Methods: We performed a secondary analysis of an observational, cross-sectional study, in a single Portuguese Rheumatology outpatient department using a structural equation modelling estimation to analyse the associations between fatigue and disease activity, perceived disease impact, personality traits, depression and anxiety dimensions. Fatigue was assessed using the RAID-F (0-10 NRS) from the Rheumatoid Arthritis Impact of Disease (RAID) questionnaire. Disease activity was measured with the Disease Activity Score 28 joints (DAS28), in its three variables (3v) and C-reactive protein (CRP) variant – DAS28CRP3. Disease Impact was evaluated through the individual domains of RAID.7 questionnaire excluding fatigue and coping. Depressive and anxiety symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS), whereas personality was assessed by the Ten Item Personality Inventory (TIPI). We designated the latent higher order factor derived from TIPI as "Positive" personality, to denote the predominantly adaptive nature of the represented dimensions. Haemoglobin (mg/dl) was also collected. Descriptive and correlational analyses were performed using SPSS®, v. 29 (IBM, Armonk NY, USA) software. Statistically significant effects were assumed for p<0.05. Results: We included a total of 214 RA patients (79.9% female). Mean age is 57.7 years with standard deviation (SD) 12.7 years, mean disease duration is 11.4 years, SD 8.8 years and mean DAS28CRP3v is 2.5, with SD 0.95. The results obtained in the structural equation model indicated a good fit to the data, explaining 80% of the variance of the fatigue (R²=0.80). "Positive" personality, disease activity and depression explained 56% of the variance of perceived impact of disease (R²=0.56). We found a direct association between disease activity [DAS28CRP3v] and impact of disease (β=0.21; p=0.001) (Figure 1), and furthermore impact of disease showed a significant positive direct relation with fatigue (β=0.89; p<0.001). The model also showed a direct negative relation between "positive" personality traits and impact of disease (β=-0.51; p<0.001). Furthermore, depression showed a significant positive direct relation with impact of disease (β=0.25; p=0.01) and a significant negative direct relation with "positive" personality (β=-0.29; p=0.01). In our model, Haemoglobin has a slight indirect effect through disease activity. Finally, anxiety showed a significant negative direct relation with positive personality (β=-0.77; p<0.001). Conclusion: These results suggest that perceived impact of disease plays a direct contributing role for fatigue in patients with RA. Disease activity, positive personality traits, and comorbidities such as depression and anxiety may play an indirect role. This highlights the importance of expanding beyond disease activity in the management of RA, and the need for a multidisciplinary approach. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.