Association of Somatic Comorbidities and Comorbid Depression With Mortality in Patients With Rheumatoid Arthritis: A 14-Year Prospective Cohort Study

Objective. Patients with rheumatoid arthritis (RA) have a significantly increased risk of mortality compared with the general population. 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. The purpose of this study was 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 questionnaires. The mortality status was obtained from the Statistics Netherlands for the period 1996-2011 for 99% of the patients. Somatic comorbidity was assessed in 1997, 1998, 1999, and 2008 and measured by a national population-based questionnaire including 20 chronic diseases. Comorbid depression was assessed in 1997, 1998, and 1999 and measured with the Center for Epidemiologic Studies 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 +/- SD age was 59.3 +/- 14.8 years, and the median (interquartile range) disease duration was 5.0 (2.0-14.0) years. A total of 345 patients died during the study period. Comorbidities that were associated with mortality were circulatory conditions (hazard ratio [HR] 1.60 [95% confidence interval (95% CI) 1.15-2.22]), respiratory conditions (HR 1.43 [95% CI 1.09-1.89]), cancer (HR 2.00 [95% CI 1.28-3.12]), and depression (HR 1.35 [95% CI 1.06-1.72]). Conclusion. Comorbid circulatory conditions, respiratory 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.