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Multifactorial explanatory model of depression in patients with rheumatoid arthritis: a structural equation approach.

OBJECTIVES
Depressive symptoms are common among patients with rheumatoid arthritis (RA). This study was aimed at developing a multifactorial explanatory model that evaluated the influence of personality traits, disease activity, perceived disease impact, and comorbidities.


METHODS
This cross-sectional study used structural equation modelling estimation to analyse the associations between these dimensions, pursuing three hypotheses. Depressive symptoms were assessed using the Hospital Anxiety and Depression Scale, disease impact by the Rheumatoid Arthritis Impact of Disease score, personality by the Ten Item Personality Inventory and the disease activity through the Disease Activity Score 28 joints. The influence of comorbidities was investigated by multigroup analysis.


RESULTS
The final model derived from data of 254 patients presented a good fit. Disease activity had an indirect relation with depressive symptoms mediated by disease impact (β=0.17, p<0.001), but the direct relationship between disease activity and depressive symptoms was not significant (β=0.09; p=0.07). "Positive" personality had a strong negative direct relation with depressive symptoms as well as an indirect relationship mediated by disease impact (total effect β=-0.61, p<0.001). The final proposed model explained 58% of the variance of depressive symptoms. Multigroup analysis showed an invariant model when comparing patients with and without comorbidities (dχ2=9.03; df=12; p=0.70).


CONCLUSIONS
Personality characteristics seem to have a major influence upon the impact of disease and the patient's adjustment to RA, including the vulnerability or resilience to depression. Individual personality traits deserve attention in tailored assessment and treatment of patients with RA, in order to optimise outcomes.