Association between rheumatoid arthritis and interstitial lung disease and impact of serologic status: a large-scale longitudinal study

Interstitial lung disease (ILD) leads to worse outcomes in subjects with rheumatoid arthritis (RA). Few large-scale longitudinal studies have provided comprehensive data on the incidence and risk of ILD in RA compared with non-RA populations. We compare the risk of incident ILD in subjects with RA and matched controls, while also evaluating the impact of RA serologic status. Using the Korean National Health Insurance Service Data between 2010 and 2017, we identified 52,325 individuals with RA and 261,625 without RA. During a median follow-up period of 4.4 years, 3.7% of the RA cohort and 0.5% of the matched cohort developed ILD, with incidence rates of 8.30 and 1.01 per 1,000 person-years. Compared to controls, the risk of incident ILD was significantly higher in the RA cohort (adjusted hazard ratio [aHR] 7.84 [7.29–8.44]), and seropositive and seronegative RA exhibited aHRs of 9.00 (8.34–9.72) and 4.81 (4.25–5.44). Although the risk of ILD was higher in seropositive RA than seronegative RA, the risk of developing ILD was also higher in subjects with seronegative RA than in matched controls, suggesting that close monitoring for ILD should be performed in this population.