All-cause and cause-specific mortality of patients with rheumatoid arthritis in Korea: A nation-wide population-based study.

Abstract

To compare all-cause and cause-specific mortality between rheumatoid arthritis (RA) patients versus the general population of Korea. A nationally representative RA population aged≥40 years was identified from Korea National Health Insurance Service (KNHIS) database. We estimated age- and sex-adjusted all-cause and cause-specific standardized mortality ratios (SMRs) with 95% confidence intervals (CIs), comparing RA patients to the general population. Subgroup analyses were done by sex, age group, calendar year, and biologics use. We identified 79,352 RA patients with 6404 deaths during 2011-2016. The all-cause SMR [95% CI] of RA patients compared to the general population was 1.53 [1.49-1.56]. The top five causes of death were cancer (19.5%), respiratory disease (19.1%), cardiovascular disease (18.8%), systemic rheumatic diseases (9.5%, 9.1% due to RA), and infection (6.1%). Cause-specific SMRs [95% CI] were 0.95 [0.90-1.01] for cancer, 3.34 [3.15-3.52] for respiratory disease, 1.26 [1.18-1.33] for cardiovascular disease, 3.41 [3.08-3.75] for infection, and 4.88 [3.10-6.65] for non-RA systemic rheumatic disease. The SMR of RA population was slightly higher among men than women, and highest in their 60s and 70s. The yearly SMR increased from 1.10 [1.01-1.18] in 2011 to 1.85 [1.75-1.95] in 2016 due to population aging and comorbidity accumulation. Users of biologics showed a higher SMR than non-users (1.82 [1.69-1.96] vs. 1.50 [1.46-1.54]), due to higher RA activity, and more comorbidities despite a younger mean age. RA patients in Korea experienced 1.5-fold increase in all-cause mortality compared to the general population. Except for cancer, the top five causes of death were associated with excess mortality among RA patients. RA-associated mortality was largely determined by age, RA activity, and comorbidity status.