This systematic review and meta-analysis examined the strength of association between rheumatoid arthritis and depression. In addition, we investigated the extent to which sociodemographic characteristics, level of pain, and method of assessing depression might affect the degree of depression.
CD-ROM databases and bibliographies were searched to identify all studies comparing depression in patients with rheumatoid arthritis and control subjects using standardized assessments. Effect sizes (Pearson's r) and probabilities were combined across studies. We examined the extent to which the association between rheumatoid arthritis and depression could be attributed to level of pain (using contrasts), sociodemographic differences between groups (combining methodologically restricted studies), and methods of assessing depression (examining heterogeneity across studies).
Twelve independent studies comparing depression in patients with rheumatoid arthritis with depression in healthy control subjects were found. Effect sizes for depression were small to moderate (r =.21, p <.0001; heterogeneous). This effect was not reduced in studies controlling for sociodemographic characteristics (r =.27, p <.0001). The effect sizes did vary in a linear manner in proportion to the effect size for pain (z = 2.67, p =.0064). The effect sizes produced by different measures of depression were heterogeneous (chi(2) for Fisher's Z = 24.6, p =.0002), with the Hospital Anxiety and Depression Scale giving effect sizes most dissimilar to those of other measures.
Depression is more common in patients with rheumatoid arthritis than in healthy individuals. This difference is not due to sociodemographic differences between groups, but it may be attributable, in part, to the levels of pain experienced. Variation in the methods of assessing depression partly accounts for the differences among studies examining the levels of depression in patients with rheumatoid arthritis.