Chronic comorbidity in patients with early rheumatoid arthritis: a descriptive study.

OBJECTIVE: To study the presence of chronic coexisting diseases in patients with rheumatoid arthritis (RA) and its effect on RA treatment, disease course, and outcome during the first years of the disease.
METHODS: From January 1985 to December 1990, 186 patients with recent onset RA were enrolled in a prospective longitudinal study. Between January 1991 and November 1992 patients were interviewed on the basis of a comorbidity questionnaire. For analysis the diseases were coded according to the International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) medical diagnoses. Disease activity during the period of followup was measured by the Disease Activity Score. Outcome in terms of physical disability (Health Assessment Questionnaire) and radiological damage (Sharp's modified version) over 3 and 6 year periods was determined.
RESULTS: In the group of 186 patients, with mean disease duration of 4.3 years at January 1991, 50 patients (27%) reported at least one chronic coexisting disease. The most frequently reported coexisting diseases were of cardiovascular (29%), respiratory (18%), or dermatological (11%) origin. For the major part (66%) chronic coexisting diseases were already present before onset of RA. No statistically significant differences in use of disease modifying antirheumatic drugs or corticosteroids were observed between RA patients with and without chronic coexisting diseases. No statistically significant differences were found in disease activity or in outcome in terms of physical disability and radiological damage over 3 and 6 year periods between the 2 groups with RA.
CONCLUSION: The results showed that about 27% of patients with RA in this inception cohort had at least one chronic coexisting disease. Treatment, disease course, and outcome did not differ between patients with and without chronic coexisting diseases during the first years of the disease.