Background/Purpose: Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to functional disability and premature mortality. We aimed to identify the status of disability and mortality in patients newly diagnosed with seropositive RA who were followed up for up to 10 years, as compared with the general population in Korea.

Methods: We conducted a nationwide population-based study using a National Health Insurance Service-National Sample Cohort of a Korean population consisting of 1 million individuals who submitted medical care claims between 2002 and 2013. A RA diagnosis was defined as the diagnostic code for seropositive RA (International Classification of Diseases code M05) with the prescription of any disease-modifying anti-rheumatic drug (DMARD).

Results: The analysis included 1655 incident seropositive RA patients and 8275 non-RA controls, matched by age, sex, and income. In RA patients, the most commonly used DMARD was hydroxychloroquine (n=1180, 71.30%), followed by methotrexate (n=1150, 69.49%), leflunomide (n=434, 26.22%), sulfasalazine (n=598, 36.13%), and bucillamine (n=269, 16.25%). The most commonly used biologic DMARD was adalimumab (n=42, 2.54%), followed by etanercept (n=29, 1.75%), infliximab (n=14, 0.85%), and rituximab (n=8, 0.48%).

The disability rate in the first 10 years of the disease increased in RA patients compared with non-RA controls (odds ratio [OR] 2.27, 95% confidence interval [CI] 1.75–2.93, p<0.0001). The physical disability rate significantly increased (OR 3.81, 95% CI 2.80–5.18, p<0.0001). During the follow-up period, 88 RA patients (0.05%) and 200 non-RA controls (0.02%) developed disability regardless of cause and severity. Of these, 73 and 99 had physical disabilities (82.95% and 49.50% of all disabilities, respectively).

The mortality rate in the first 10 years of the disease also significantly increased in the RA group compared with the non-RA controls (OR 1.33, 95% CI 1.05–1.69, p=0.02), especially in the death caused by infection (OR 4.39, 95% CI 1.59–12.12, p<0.01). During the follow-up period, 88 RA patients (0.05%) and 335 non-RA controls (0.04%) died. The main causes of death in the first 10 years of RA were malignancy (19.32%), cardiovascular disease (15.90%), RA itself (11.36%), and infection (7.95%). In the non-RA control group, the main causes of death were malignancy (36.41%), cardiovascular disease (21.50%), and respiratory disease (7.16%).

Conclusion: Seropositive RA patients had higher mortality and disability than the non-RA population in the first 10 years of the disease. Further study about the determinants of disability and mortality is needed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/disability-status-mortality-and-leading-causes-of-death-in-seropositive-rheumatoid-arthritis-patients-a-population-based-study-in-korea/