Somatic comorbidity and comorbid depression are associated with mortality among patients with established rheumatoid arthritis: an eleven years follow-up cohort study

Background Rheumatoid Arthritis (RA) is associated with premature mortality (1). Somatic comorbidity has been found to be one of the most important predictors for premature mortality (2). Comorbid conditions that are associated with premature mortality are: cardiovascular diseases, respiratory diseases, gastrointestinal system disorders, genitourinary diseases, hematologic diseases, infectious diseases, and malignancies. A few studies have found comorbid depression to be associated with an increased risk for mortality (3). The combination of both somatic comorbidity and comorbid depression as a risk factor for mortality has not yet been investigated. Whether this combination is an additional risk factor for premature mortality is important information for clinicians to be able to adapt their screening process and when necessary their treatment. Objectives To investigate which comorbid conditions are associated with premature mortality and if the combination of a somatic comorbid condition and comorbid depression is more associated with premature mortality than one of these conditions alone. Methods Longitudinal data over a period of eleven years were collected from 882 patients with RA at study inclusion. Data by means of self-reported questionnaires were collected in 1997, 1998, 1999, 2002 and 2008. Of all of the participants included at baseline, the mortality status was obtained from the register of the Statistics Netherlands. Somatic comorbidity was measured by a questionnaire including 20 chronic diseases. Comorbid depression was measured with the Center for Epidemiologic Depression Scale. To study the relationship between comorbidity and survival among RA patients, we performed a Cox regression analysis. Results 78% of the patients at baseline were women. The mean age was 59.3 (SD 14.8) years and the median disease duration was 5.0 (IQR 2.0-14.0) years. Comorbid conditions that were associated with premature mortality were respiratory conditions, gastrointestinal conditions, cancer and comorbid depression. The combination of a somatic comorbid condition and comorbid depression did not lead to an additional risk for premature mortality. Conclusions Both somatic comorbidity and comorbid depression are a risk factor for premature mortality among patients with RA. These results emphasize the importance of paying attention to both somatic comorbidity and comorbid depression in clinical practice, and highlight the importance of ascertaining the presence of such comorbidities and to adjust treatment when necessary. References Naz SM, Symmons DPM. Mortality in established rheumatoid arthritis. Best Pract Res Clin Rheumatol 2007; 21(5):871-883. Sokka T, Abelson B, Pincus T. Mortality in rheumatoid arthritis: 2008 update. Clin Exp Rheumatol 2008; 26(5 Suppl 51):S35-S61. Ang DC, Choi H, Kroenke K, Wolfe F. Comorbid depression is an independent risk factor for mortality in patients with rheumatoid arthritis. J Rheumatol 2005; 32(6):1013-1019. Disclosure of Interest None Declared