Prevalence and predictive factors of comorbidity in rheumatoid arthritis patients monitored prospectively from disease onset up to 20 years: lack of association between inflammation and cardiovascular disease

Abstract

Objectives: To study the prevalence of comorbid conditions at diagnosis and during follow-up in a cohort of patients with early rheumatoid arthritis (RA) followed prospectively over 20 years, and to identify possible early predictive factors for future comorbidities.

Methods: A community-based cohort of 183 patients (mean age 52 years, 63% female) with early RA was recruited between 1985 and 1989. The presence of comorbidity at RA diagnosis and the occurrence of additional comorbidities were recorded continuously. Possible predictors of future comorbidities were analysed using the Cox proportional hazards model.

Results: At RA diagnosis, at least one comorbid condition was present in 43% of the patients. Cardiovascular diseases (CVDs), including hypertension (16% of patients) and malignancy (6% of patients), were most common. In total, 82% of patients developed additional comorbidities during follow-up. CVD and malignancies remained the most frequent comorbidities. Higher age [p < 0.001, odds ratio (OR) 1.03, 95% confidence interval (CI) 1.01–1.15] and the presence of any comorbidity at diagnosis (p = 0.02; OR 1.64, 95% CI 1.08–2.52) predicted future comorbidity. Measures of inflammation at diagnosis or during follow-up were not predictive for development of CVD.

Conclusion: Comorbidity was present in a considerable proportion of patients in this cohort. More than 40% of patients had another disease at inclusion and during follow-up and > 80% developed additional conditions. The pattern of comorbidity remained unchanged, with CVD and malignancy being most common. Older age and the presence of comorbidity at RA diagnosis predicted the development of comorbidities. The degree of inflammation at any time point was not predictive of future CVD.

Acknowledgements

This study was supported by grants from the Swedish Rheumatism Association, the Swedish Research Council, the Medical Faculty of the University of Lund, Alfred Österlund's Foundation, the Crafoord Foundation, Greta and Johan Kock's Foundation, the King Gustaf V Foundation, and Lund University Hospital.