OBJECTIVE To examine the association between MTX, LEF and tacrolimus use and the progression of RA-associated interstitial lung disease (ILD).

METHODS The Korean RA-ILD cohort prospectively enrolled patients with RA-associated ILD at multiple centres from 2015 to 2018 and followed up with them for 3 years. ILD progression was defined by any of the followings: a decrease of ≥10% in forced vital capacity, a decrease of ≥15% in the diffusing capacity of the lung for carbon monoxide, or death from respiratory failure.

RESULTS Of 143 patients, 64 patients experienced ILD progression during a median follow-up period of 33 months. The use of MTX [adjusted hazard ratio (aHR), 1.06; 95% CI, 0.59, 1.89], LEF (aHR, 1.75; 95% CI, 0.88, 3.46) and tacrolimus (aHR, 0.94; 95% CI, 0.52, 1.72) did not increase the risk of ILD progression. However, the association between LEF use and the risk of ILD progression was significant in subgroups with poor lung function (aHR, 8.42; 95% CI, 2.61, 27.15). Older age, male sex, a shorter RA duration, higher RA disease activity and extensive disease at baseline were independently associated with ILD progression.

CONCLUSION None of the three treatments increased the risk of RA-associated ILD progression, except for LEF, which increased the risk of ILD progression in patients with severe ILD. The appropriate use of conventional synthetic disease-modifying antirheumatic drugs considering RA disease activity and ILD severity would be important for the management of RA-associated ILD.