Disability and depression in rheumatoid arthritis. A multi-trait, multi-method investigation

Area of Science:

• Rheumatology
• Psychiatry
• Health Outcomes Research

Background:

• Rheumatoid arthritis (RA) significantly impacts patients' quality of life, often co-occurring with depression.
• Accurate measurement of disability and depression is crucial for effective RA management.
• Existing depression scales may not be fully validated for RA populations, potentially confounding results.

Purpose of the Study:

• To assess the convergent and divergent validity of disability and depression measures in RA patients.
• To investigate the impact of somatic symptoms on depression assessments in RA.
• To identify more accurate methods for measuring depression in individuals with RA.

Main Methods:

• Analysis of data from 107 patients with classic or definite rheumatoid arthritis.
• Comparison of self-reported disability scores (Health Assessment Questionnaire) with clinician and spouse ratings.
• Factor analysis of the Beck Depression Inventory (BDI) and assessment of BDI item relevance to RA disease severity.

Main Results:

• High correlation between self-reported disability and external ratings of disability.
• Significant but smaller correlations between disability scores and depression ratings.
• Beck Depression Inventory (BDI) showed contamination from RA disease severity items.
• A dysphoric mood subcomponent of the BDI demonstrated higher validity for depression in RA.

Conclusions:

• Disability and depression are positively correlated in RA, but somatic items in depression scales can inflate this association.
• The Beck Depression Inventory (BDI) may overestimate depression in RA due to symptom overlap.
• A mood-focused assessment is recommended for measuring depression in rheumatoid arthritis patients.