Calcium supplementation and inflammation increase mortality in rheumatoid arthritis: A 15-year cohort study in 609 patients from the Oslo Rheumatoid Arthritis Register.

OBJECTIVE: To investigate whether osteoporosis or use of calcium supplementations predict all-cause mortality, or death from CVD, in a longitudinal cohort of patients with rheumatoid arthritis (RA).
METHODS: Patients in the Oslo RA register (ORAR) were examined, and bone mineral density was measured in 1996. The cohort was linked to the Norwegian Cause of Death registry on December 31, 2010. Death from CVD was defined in 3 following different outcomes: (1) primary atherosclerotic death, (2) atherosclerotic death as one of the 5 listed causes of death, and (3) CVD according to World Health Organization (WHO) definition as primary cause of death. Baseline predictors of all-cause mortality and death from CVD were identified in separate Cox regression models, using backwards selection. Sensitivity analyses were performed including analyses of interactions and competing risk.
RESULTS: A total of 609 patients were examined in 1996/1997. By December 31, 2010, 162 patients (27%) had died, resulting in 7439 observed patient-years. Of the deceased, 40 (24.7%) had primary atherosclerotic death. In the final model of all-cause mortality increased baseline ESR [hazard ratio (HR) 1.02 per mm/h, 95% CI: 1.01-1.03], calcium supplementation (1.74, 1.07-2.84), and osteoporosis, defined as a T score ≤2.5 SD at any location, (1.58, 1.07-2.32) predicted higher mortality rates, in models adjusted for age, gender, and a propensity score. In the final model of primary atherosclerotic death, increased ESR (1.03 per mm/h, 1.01-1.05) and calcium supplementation (3.39, 1.41-8.08), predicted higher mortality.
CONCLUSIONS: Increased baseline ESR and use of calcium supplementation were predictors of increased all-cause mortality and risk of death from CVD in this longitudinal study of patients with RA.