Abstract
Rheumatoid arthritis (RA) is a systemic autoimmune disease whose main extra-articular organ affected is the lung, sometimes in the form of diffuse interstitial lung disease (ILD) and conditions the prognosis. A multicenter, observational, descriptive and cross-sectional study of consecutive patients diagnosed with RA-ILD. Demographic, analytical, respiratory functional and evolution characteristics were analyzed to evaluate the predictors of progression and mortality. 106 patients were included. The multivariate analysis showed that the diagnostic delay was an independent predictor of mortality (HR 1.11, CI 1.01–1.23, p = 0.035). Also, age (HR 1.33, 95% CI 1.09–1.62, p = 0.0045), DLCO (%) (HR 0.85, 95% CI 0.73–0.98, p = 0.0246), and final SatO2 (%) in the 6MWT (HR 0.62, 95% CI 0.39–0.99, p = 0.0465) were independent predictor variables of mortality, as well as GAP index (HR 4.65, 95% CI 1.59–13.54, p = 0.0051) and CPI index (HR 1.12, 95% CI 1.03–1.22, p = 0.0092). The withdrawal of MTX or LFN after ILD diagnosis was associated with disease progression in the COX analysis (HR 2.18, 95% CI 1.14–4.18, p = 0.019). This is the first study that highlights the diagnostic delay in RA-ILD is associated with an increased mortality just like happens in IPF.
Highlights
Abbreviations 6MWT Six minutes walking test ACR/EULAR American College of Rheumatology/European League Against Rheumatism CCP Anticyclic citrullinated peptide composite physiologic index (CPI) Composite physiologic index CTD-ILD Connective tissue disease associated interstitial lung disease DAS28 Disease activity score 28 DLCO Diffusion capacity of the lung for carbon monoxide ESR Erythrocyte sedimentation rate forced vital capacity (FVC) Forced vital capacity GAP index Gender, age and physiology variables index Good Clinical Practices (GCPs) Good clinical practices HRCT High-resolution computed tomography interleukin 6 (IL-6) Interleukin 6 ILD Interstitial lung disease idiopathic pulmonary fibrosis (IPF) Idiopathic pulmonary fibrosis KL-6 Krebs von den Lungen 6 LEF Leflunomide MTX Methotrexate non-specific interstitial pneumonia (NSIP) Non-specific interstitial pneumonia
Oher factors associated with a higher mortality in Rheumatoid arthritis (RA)-ILD are age, male sex, worse pulmonary function at diagnosis, duration of RA, disease RA activity, extensive lung involvement on chest HRCT and elevated serum levels of Krebs von den Lungen 6 (KL-6) b iomarker[9,10,11,12,13]
A confident usual interstitial pneumonia (UIP) pattern in the HRCT was present in 51.9% of the patients
Summary
Abbreviations 6MWT Six minutes walking test ACR/EULAR American College of Rheumatology/European League Against Rheumatism CCP Anticyclic citrullinated peptide CPI Composite physiologic index CTD-ILD Connective tissue disease associated interstitial lung disease DAS28 Disease activity score 28 DLCO Diffusion capacity of the lung for carbon monoxide ESR Erythrocyte sedimentation rate FVC Forced vital capacity GAP index Gender, age and physiology variables index GCPs Good clinical practices HRCT High-resolution computed tomography IL-6 Interleukin 6 ILD Interstitial lung disease IPF Idiopathic pulmonary fibrosis KL-6 Krebs von den Lungen 6 LEF Leflunomide MTX Methotrexate NSIP Non-specific interstitial pneumonia. Oher factors associated with a higher mortality in RA-ILD are age, male sex, worse pulmonary function at diagnosis, duration of RA, disease RA activity, extensive lung involvement on chest HRCT and elevated serum levels of Krebs von den Lungen 6 (KL-6) b iomarker[9,10,11,12,13]. These findings are all based on small series of cases, they have been reproduced consistently in different patient cohorts. There is no clear definition of progression for RA-ILD6,14–17
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