Somatic cormobidities and comorbid depression are associated with mortality among patients with rheumatoid arthritis: a 14-year prospective cohort study

Background Patients with rheumatoid arthritis (RA) have a significantly increased risk of mortality compared with the general population [1]. Although the management of RA improved in the last decades, the survival in patients with RA has not improved to the same degree as that of the general population [2,3]. One of the most important predictors for mortality is somatic comorbidity. Moreover, studies have demonstrated that comorbid depression is associated with mortality. Which specific comorbidities are associated with mortality is less investigated. Objectives To investigate the association of a wide range of comorbidities with mortality in patients with RA. Methods Longitudinal data over a 14-year period were collected from 882 patients with RA. Data were assessed with self-reported questionnaires. The mortality status was obtained from the Statistics Netherlands for the period 1996-2011 for almost all of the participants included at baseline (99,8%). Somatic comorbidity was assessed in 1997, 1998, 1999 and 2008. Somatic comorbidity was measured by a national population-based questionnaire including 20 chronic diseases, of which nine categories of chronic somatic comorbidity were created. Comorbid depression was assessed in 1997, 1998 and 1999. Comorbid depression was measured with the Center for Epidemiologic Depression Scale. Cox regression was used to study the relationship between comorbidity and mortality. Results At baseline, 72% of the patients 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. Comorbidities that were associated (Hazard Ratio [95% confidence intervals]) with mortality were circulatory conditions (1.62 [1.17-2.26]), respiratory conditions (1.46 [1.11-1.93]), digestive conditions (1.51 [1.02–2.22]), cancer (2.03 [1.30-3.18]) and depression (1.39 [1.09-1.77]). Conclusions Comorbid cardiovascular conditions, respiratory conditions, digestive conditions, cancer, and depression are associated with mortality among patients with RA. Careful monitoring of these comorbidities during the course of the disease and adequate referral may improve health outcomes and chances of surviving.