Study of the relationship between anti-citrullinated protein antibodies and occurrence of interstitial lung disease in patients with rheumatoid arthritis

Introduction Rheumatoid arthritis (RA) is a systemic inflammatory disorder that most commonly affects the joints. Interstitial lung disease (ILD) is the most common pulmonary manifestation of RA-associated ILD. Patients with RA typically have circulating auto-antibodies, the most common being rheumatoid factor and anti-cyclic citrullinated protein antibodies (ACPA). Aim To determine the occurrence of ILD in patients with RA and its relation to anti-citrullinated protein antibodies. Patients and methods The study was conducted on 40 patients diagnosed according to ACR/EULAR 2010 criteria for diagnosis of RA. They were divided into two groups according to ACPA positivity: group I included 20 patients with RA who were ACPA positive, and group II included 20 patients with RA who were ACPA negative. Exclusion criteria Patients with interstitial pneumonia, asbestos exposure, other connective tissue diseases such as systemic lupus erythematosus and systemic sclerosis, autoimmune hepatitis, and hepatitis C virus infection were excluded. Patients and methods The participates underwent thorough medical history taking, full clinical examination, disease activity score-28 based on C-reactive protein and functional assessment questionnaire (Health Assessment Questionnaire) score, complete blood count, SGPT, SPOT, urea, creatinine, erythrocyte sedimentation rate first hour and rheumatoid factor, ACPA titer, high-resolution computed tomography of the chest, radiological examination for both hands and feet, BMI, ECHO, pulmonary function tests, and assessment of pulmonary artery pressure. An informed consent was taken from all patients in the study. Results ACPA-positive patients with RA are accompanied with a statistically significant restrictive pattern of pulmonary function tests. Positive high-resolution computed tomography findings indicate RA-ILD. Conclusions In RA, high titer of ACPA may be related to the development of ILD.