Depression is a frequently occurring comorbid condition in patients with rheumatoid arthritis (RA), and research into the temporal relationships regarding its onset has mainly focused on functional status. The study aim was to examine temporal associations of the diverse measures of RA disease activity with incident self-reports of depressive symptoms.
RA patients from the Consortium of Rheumatology Researchers of North America (CORRONA) registry were utilized. Cox regression was used to assess the lagged time-varying association of RA disease activity with the incident onset of depressive symptoms as measured using a single-item depression question. Predictor variables included joint counts, global assessments, pain, function, serum biomarkers, and composite disease activity. Hazard ratios (HRs) comparing categorical quintiles were estimated with 95 % confidence intervals.
Every metric of disease activity, except inflammatory markers, were significantly associated with the self-reported onset of depressive symptoms. Adjusted HRs comparing fifth quintiles to first quintiles were the following: CDAI = 2.3 [2.1-2.7]; pain = 2.3 [2.0-2.6]; SJC = 1.4 [1.4-1.6]. When examining successive self-reports (two consecutive), the magnitude of the associations greatly increased: CDAI = 3.6 [2.5-5.0].
The data suggest depressive symptom onset in RA patients is related to measures reported by the patient: pain, functional status, and global disease activity; and measures reported by providers, rather than biological markers. The magnitude of the associations, however, were greater for the patient-reported measures when compared to physician assessments, implying that patients' experience of their disease activity may be a precipitating factor of depression onset.