A dual pathway model of daily stressor effects on rheumatoid arthritis

This study evaluated the initial promise of a dual-pathway conceptual model linking daily event stressors to rheumatoid arthritis (RA) disease activity through changes in immune system activation and mood. Fifty individuals, who were studied on five occasions two weeks apart, reported daily event stressors on the Daily Life Experience Checklist, daily mood on an abbreviated version of the Profile of Mood States-B, and daily joint pain on the Rapid Assessment of Disease Activity in Rheumatology. Serial clinical examinations comprised ratings of joint tenderness and swelling, and blood drawn during exams was analyzed for sedimentation rate (an indicator of systemic inflammation) and soluble interleukin-2 receptors (a marker of immune system activation known to correlate with RA disease activity). Across-person analyses failed to establish links from daily event stressors to either disease activity or composites of joint pain and joint inflammation when associations were adjusted for the effect of neuroticism on self-report measures. Pooled within-person analyses, however, were generally consistent with the relations predicted by the dual-pathway model. Increases in daily event stressors during the week preceding each clinical exam were associated with increased joint pain (regardless of changes in mood). At the same time, increased daily stressors were indirectly associated with decreased joint inflammation through reduction in levels of soluble interleukin-2 receptors. The dual-pathway model, which may be limited to short-term psychological and psychoimmunologic processes, underscores the importance of distinguishing potentially opposing effects of stress on pain versus inflammation in individuals with rheumatoid arthritis.