Self-reported pain is one of the core endpoint measures in RA. The objective of this cross sectional study of 238 patients with rheumatoid arthritis (RA) was to examine the relationship between self-reported pain intensity, sociodemographic variables, anxiety, and depressive symptoms.
A weighted sum score of pain intensity was constructed by combining a visual analog pain scale with items from the Arthritis Impact Measurement Scales (AIMS) and the Nottingham Health Profile. Symptoms of anxiety and depression were measured by subscales of
Multiple regression analyses showed no significant effects of age, sex, income, or level of education on self-reported pain intensity, whereas there was a significant association between the pain index and anxiety and depressive symptoms. The correlation between the pain index and anxiety, and the pain index and depression, was 0.46 for both. Controlling for sociodemographic variables, the Ritchie index, erythrocyte sedimentation rate, and C-reactive protein, the standardized regression coefficients were 0.33 and 0.31 of the pain index on the AIMS anxiety and depression subscale, respectively. Furthermore, the results indicate that the effect of inflammation on mental distress is mediated by pain.
Self-reported pain in RA is not significantly influenced by sex, age, level of education, or income. Even when controlling for disease activity, there was a considerable correlation between self-reported pain and mental distress. Furthermore, our study lends support to the hypothesis that mental distress is mainly secondary to pain rather than vice versa.