INTERSTITIAL LUNG DISEASE RELATED TO RHEUMATOID ARTHRITIS. WHAT DO WE DON’T KNOW? THE LIRA STUDY (LUNG INVOLVEMENT IN RHEUMATOID ARTHRITIS)

Background: Interstitial lung disease (ILD) is one of the more frequent and potentially severe extra-articular manifestation of rheumatoid arthritis (RA). ILD significantly decreases the survival and quality of life of patients and influences the treatment approach to the patient. Despite its clinical relevance, the prevalence, incidence and survival of RA-ILD is unknown and supposed on the base of retrospective data or registry-based studies. Objectives: For the first time, the Lung Involvement in Rheumatoid Arthritis (LIRA) study aims to investigate epidemiology, features and prognosis of RA-ILD patients in a prospective international multicentre study. Methods: All RA patients referring to the involved centres will be evaluated every six months with a digital stethoscope and a software able to identify velcro crackles with a diagnostic accuracy of 83.9% (VECTOR). In fact, velcro crackles are virtually identified in all stages of fibrosing alveolitis like RA-ILD, and their search is as a simple and reliable method to screening patients to be undergone to high resolution computed tomography (HRCT). For each patient, clinical and serological data are recorded at baseline and every six months; when velcro crackles or other conditions suspicious for ILD, such as cough or dyspnoea, are detected, a HRCT is requested to confirm ILD. Patients with ILD periodically perform pulmonary function tests to monitor lung function evolution. Results: At now, 205 RA patients have been enrolled (female/male 161/44, mean age 64.8±12.9 years, mean disease duration 14.2±8.9 years), anti-citrullinated peptides antibodies (ACPA) and rheumatoid factor (RF) were positive in 77.1% and 78.1%, respectively. The prevalence of ILD was 21% (43 patients). In other 13 patients the HRCT is ongoing; therefore, we could suppose up to a prevalence of 27.3%. Patients with ILD were symptomatic in 53.5% of cases (23 patients), they are more frequently males and were older than patients without ILD (mean age 73.2±7.4 and 62.7±13.2; p<0.0001, female/male ratio 139/23 vs 22/21; p<0.0001) without significant differences regarding disease duration, positivity for ACPA or RF. Conclusion: The prevalence and the incidence of RA-ILD is still not well defined. Preliminary data of our study confirm a prevalence of ILD higher than 20%, patients are asymptomatic in almost the half of cases and more frequently males and elderly. Our study can help to define the clinical history of these patients, the possible association with clinical and serological features and the supposed role of some drugs