Automated quantification system predict a progressive phenotype in rheumatoid arthritis-associated interstitial lung disease

The prognosis of interstitial lung disease (ILD) in rheumatoid arthritis (RA) patient is difficult to predict. To determine the prognostic value of automated quantification system (AQS) in patient with RA-ILD. We analyzed clinical data and high resolution computed tomography (HRCT) images of 144 patients with RA-ILD retrospectively. The quantitative lung fibrosis (QLF, sum of reticulation and traction bronchiectasis) and quantitative ILD (QILD, sum of QLF, honeycombing [QHC] and ground glass opacity [QGG]) scores were measured on HRCT by AQS. Of all patients, the mean age was 61.2 years, and 43.8% were male, and 5-year mortality was 30.5% (median follow up: 52.2 months). Non-survivors showed older age and higher erythrocyte sedimentation rate (ESR) than survivors. In the multivariable Cox analysis, higher QLF, QHC and QILD scores were independent prognostic factors, along with older age and higher ESR. In the receiver operating characteristic analysis, QLF score showed better performance in predicting 5-year mortality than QHC and QGG scores, but was similar to QILD score (Fig. 1a). Patients with high QLF score (>12% of total lung volume) showed higher 5-year mortality (50% vs 17.4%, p <0.001) than those with low QLF score (Fig. 1b). QLF score might be useful to predict prognosis in patients with RA-ILD, and high QLF score may differentiate a progressive phenotype with poor survival.