Influence of demographic and clinical factors on the mortality rate of a rheumatoid arthritis cohort: A 20-year survival study

Abstract

Objectives: To describe the mortality rate (MR) and standardized MR (SMR) of an incident cohort of rheumatoid arthritis (RA) patients followed up for 20 years, and to analyze the influence on morality risk of different demographic and clinical variables, including radiographic joint damage.

Methods: Retrospective longitudinal study that included 2271 RA patients attending the rheumatology outpatient clinic of the Hospital Clínico San Carlos (Madrid, Spain), enrolled from January 1994 to February 2013 and followed up from RA diagnosis to patients׳ death or September 2013. Disability and disease activity were measured as the averaged value of the Heath Assessment Questionnaire and the erythrocyte sedimentation rate, respectively, of the first 2 years after RA diagnosis. Radiographic joint damage of hands and wrists was assessed with the Sharp/van der Heijde score. Indirect SMRs with a 95% of confidence interval (95% CI) were calculated. Cox bivariate and multivariate regression models were performed to assess risk factors for death.

Results: A total of 431 patients died (19%) during the observation time (18,482 person-years), resulting in a MR of 23 subjects per 1000 patient-years [95% CI: 21-26]. SMR was 1.89 (1.72-2.08). In the multivariate analysis, men, older age at diagnosis, the presence of rheumatoid factor, higher number of hospital admissions, greater disease activity, and greater radiographic joint damage were independently associated with greater mortality risk.

Conclusions: RA patients have an excess mortality compared with the general population. Radiological joint damage and early disease activity are independent mortality risk factors. A tighter control at early stages may be necessary to reduce mortality.

Keywords: Mortality; Radiographic joint damage; Rheumatoid arthritis; Survival analysis.