Background The prevalence of comorbidity in patients with rheumatoid arthritis (RA) is higher than in the general population (1). There is increasing evidence that comorbidity plays an important role in determining RA-related outcomes, like physical functioning (2). Little is known about the impact of comorbidity on the long term. Further, the studies that investigated the effects of comorbidity on physical functioning, did not compare the influence of both somatic and depression comorbidity. With this information clinicians can early adjust their treatment to the comorbidity.
Objectives To asses the long term association of comorbidity and physical functioning in patients with established RA.
Methods Longitudinal data were collected among 882 patients with RA of varying disease duration at inclusion in the study. Patient reported outcomes were collected in 1997, 1998, 1999, 2002 and 2008. Physical functioning was measured with the Health Assessment Questionnaire and the Physical Component Scale of the SF-36 Health Survey. Somatic comorbidity was measured by a self administered questionnaire including 13 chronic diseases. Depression comorbidity was measured with the Center for Epidemiologic Depression Scale. We distinguished four groups of patients based on comorbidity at baseline: patients 1) without comorbidity 2) with only somatic comorbidity 3) with only depression comorbidity and 4) with both somatic and depression comorbidity. The influence of comorbidity on physical functioning over time was investigated in a longitudinal analysis.
Results 882 patients respond to the questionnaire, of whom 78% were woman. The mean (SD) age of the patients at baseline was 59.3 (SD 14.8) years and the mean (SD) disease duration was 8.9(SD 9.9) years. For the total group of patients with RA, physical functioning improved over an eleven year period. Patients with comorbidity had a worse physical functioning than patients without comorbidity at all time points, by which both groups with depression comorbidity had the lowest score (p<0.01). Only, patients with both somatic and depression comorbidity at baseline had significant less improvement in physical functioning over time (p<0.05).
Conclusions Both somatic comorbidity and depression comorbidity had a negative impact on physical functioning during eleven years follow up in patients with RA, and their combination seems to be especially detrimental over time. Clinicians need to take somatic comorbidity and depression into account in screening and treatment of patients with rheumatoid arthritis to improve physical functioning in the long term.
Kroot EJ, van Gestel AM, Swinkels HL, Albers MM, van de Putte LB, van Riel PL. Chronic comorbidity in patients with early rheumatoid arthritis: a descriptive study. J Rheumatol 2001; 28(7):1511-1517.
Gabriel SE, Michaud K. Epidemiological studies in incidence, prevalence, mortality, and comorbidity of the rheumatic diseases. Arthritis Res Ther 2009; 11(3):229.
Disclosure of Interest None Declared
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