Symptom intensity/self-reported depression in RA | Arthritis Information

The symptom intensity (SI) scale, which assesses pain and fatigue, is the strongest predictor for self-reported depression (SRD) in patients with rheumatoid arthritis (RA), research shows.

Depression is common in patients with RA and adds substantially to the distress of the chronic illness, note Frederick Wolfe and Kaleb Michaud from the National Data Bank for Rheumatic Diseases in Wichita, Kansas, USA.

However, “most studies of RA and depression have not examined a full range of variables, have not dealt with nonlinear relationships, and have foundered on differences between causal models and clinical models,” say the researchers.

Wolfe and Michaud therefore collected extensive demographic and clinical data from 22,131 RA patients who were assessed for SRD between 1999 and 2008 to identify and rank clinically useful predictors for depression.

The researchers report that the cross-sectional prevalence of SRD over the study was 15.2%. Among patients who did not report depression at baseline, the incidence rate of SRD was 5.5 cases per 100 patient-years of observation while the cumulative risk for SRD after 9 years was 38.3%.

Depressed patients tended to be younger than non-depressed patients, and were more likely to be female, have lower household income, less employment, and greater work disability. They also had more comorbidities and worse scores on all RA severity scales, and they used more opioids, biologic agents, and corticosteroids, but less disease-modifying anti-rheumatic drugs.

Wolfe and Michaud remark that almost all variables were significant predictors for SRD in logistic models, but the SI scale, which combines the regional pain scale and the fatigue visual analog scale (VAS), best-predicted SRD. Presence of comorbidities ranked second followed by the regional pain scale, the patient activity scale, the patient’s global severity VAS, and fatigue VAS.

The researchers also found that once the results of the SI scale were known, other variables did not increase the ability to correctly classify patients as depressed or not depressed. Nevertheless, “in clinical practice, other variables will also be of interest, particularly comorbidity,” Wolfe and Michaud note in the journal Arthritis Care and Research.

They conclude that pain extent and fatigue, particularly in combination, are very important clinical variables that should be assessed in routine rheumatology practice.

Free abstract