Assessment of risk factors in patients with rheumatoid arthritis-associated interstitial lung disease

To assess the risk factors for interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA) and to evaluate the association of ILD with the use of methotrexate as well as with joint disease activity.

A retrospective, cross-sectional study conducted between March and December 2019 at a tertiary healthcare center, in a follow-up of RA patients who had undergone pulmonary function tests (PFT) and chest computed tomography. We evaluated the tomographic characteristics, such as the presence of ILD and its extension, as well as joint disease activity. Functional measurements, such as forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO), were also assessed. After this, a multivariate logistic regression analysis was applied in order to identify risk factors associated with ILD.

We evaluated 1.233 patients, of which 134 were eligible for this study. The majority were female (89.6%), with a mean age of 61 years old and with a positive rheumatoid factor (86.2%). RA-associated ILD (RA-ILD) was detected in 49 patients (36.6%). We found an association of RA-ILD with age ≥= 62 year, male sex, smoking history and fine crackles in lung auscultation and a decreased DLCO. The indicators of being aged ≥ 62 years old and having moderate or high RA disease activity were both independent factors associated with RA-ILD, with an odds ratio of 4.36 and 3.03, respectively. The use of methotrexate was not associated with a higher prevalence of ILD.

Age and RA disease activity are important risk factors associated with RA-ILD. Methotrexate was not associated with the development of RA-ILD in the present study.