A dose-dependent beneficial effect of methotrexate on the risk of interstitial lung disease in rheumatoid arthritis patients

Abstract

Objectives The aim of the study was to assess the influence of different factors, including treatment, on the risk of ILD in the course of RA. Methods A total of 109 RA patients were included in the analysis. High-resolution computed tomography (HRCT) of chest was obtained in each patient. Patients were classified as having ILD (ILD group) or not (N-ILD group). The ILD was graded using the semi-quantitative Warrick scale of fibrosis. Warrick extent score (WES) and Warrick severity score (WSS) were calculated separately for each patient, then combined to obtain a global score (WGS). Results In univariate analysis the presence of ILD was associated positively with age (P = 5x10-6) and negatively with MTX treatment (P = 0.0013), mean MTX dose per year of treatment (P = 0.003) and number of DMARDs used (P = 0.046). On multivariate analysis only age and treatment with MTX were independently associated with the presence of ILD. WGS was significantly lower in patients treated with MTX in a dose of ≥15 mg/week (MTX≥15 group) as compared to patients treated with lower doses of MTX (0<MTX<15 group) or not treated with MTX (N-MTX group) (P = 0.04 and P = 0.037, respectively). The ILD prevalence was higher in N-MTX group than in 0<MTX<15 group (P = 0.0036) and MTX≥15 group (0.0007). The difference in ILD prevalence between MTX≥15 and 0<MTX<15 groups was not significant, but the latter group had higher WES (P = 0.044) and trended to have higher WSS and WGS. Consclusions We found a beneficial effect of MTX on RA-ILD. Importantly, this effect seems to be dose dependent.