Rheumatoid arthritis and comorbidity. Data collected from 288 patients with rheumatoid arthritis (RA) indicated that 54% of respondents also reported other chronic conditions, and that 20% rated at least one of these other conditions as severe. Both the frequency and severity of these comorbidities affected scores on measures of depressive symptoms, social connectedness and on the Arthritis Impact Measurement Scales. These findings suggest that the absence of controls for comorbidity may bias measures of functional status among patients with RA. 