Background/Purpose: This research tested an integrated framework examining patient global assessment of disease activity (PtGA), maladaptive illness beliefs and pain as determinants of mood disturbance in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients.

Methods: The data of 232 patients (RA = 110, SLE = 122) were used to evaluate the hypothesized model in which PtGA (rated on a 10-cm visual analogue scale) directly and indirectly predicted mood disturbance (Center for Epidemiologic Studies Depression Scale and SF-36 Mental Health) through maladaptive illness beliefs (Arthritis Helplessness Index) and pain (SF-36 Pain and pain visual analog scale). Using EQS 6.1, multigroup structural equation modeling (SEM) was employed to test the model as well as the potential moderating role of diagnosis (RA compared to SLE).

Results: The model fit the data well for both patient groups [for RA: CFI = 1.00, χ²(6) = 1.93, p = .926, RMSEA < .001; for SLE: CFI = 1.00, χ²(6) = 2.04, p = .916, RMSEA < .001]. However, there were some differences in the significance and magnitude of paths between model variables, which were further assessed in multigroup analyses. As hypothesized, in both patient groups PtGA had direct positive effects on maladaptive illness beliefs and pain, and pain predicted greater mood disturbance. Moreover, illness beliefs were associated with mood disturbance for RA patients and SLE patients, though the nature of that relation was different for the two groups. Among RA patients, maladaptive illness beliefs directly predicted mood disturbance (β = .42, p < .001) whereas for SLE patients, the effect of illness beliefs on mood was indirect (mediated by pain; β_indirect = .39, p < .001). Multigroup SEM results further indicated that while illness beliefs predicted higher levels of pain in both patient groups, the effect of was significantly stronger for lupus patients (RA: β = .23, p = .006; SLE: β = .44, p < .001).

Conclusion: These findings suggest that maladaptive illness beliefs and pain may serve as mechanisms through which PtGA influences mood disturbance in both RA and SLE. Multigroup structural equation modeling elucidated differences between groups in the mediating pathways connecting PtGA to mood disturbance and have important implications for the development of targeted interventions to enhance mood regulation in RA and SLE patients.