No Risk of Interstitial Lung Disease with Methotrexate Use Save

JAMA reports a cohort study that investigated the association between methotrexate (MTX) use and Interstitial lung disease (ILD) in patients with dermatomyositis (DM). 

ILD is a complication of dermatomyositis, in up to 23% of DM patients in North America. MTX is known to rarely cause pneumonitis and less commonly pulmonary fibrosis in 0.3% to 11.6% of rheumatoid arthritis patients. 

The study included 315 DM patients starting immunomodulating treatment (IMT) after first DM diagnosis. A minority (36%) received MTX were compared to those that did not (64%). Both groups were clinically similar but MTX-exposed patients were less likely to have a DM-related malignant neoplasm and more likely to receive rituximab.  The frequency of subsequent ILD was 17% in MTX-exposed vs 16% in MTX-unexposed. Thus, there were no significant differences in ILD risk with MTX exposure (HR 0.79; 95% CI, 0.35-1.78; P = .56). 

They found similar results with MMF, known to stabilize lung function in DM but with unknown associations with ILD prevention.

These data refute the concern that MTX may induce ILD.