Retrospective assessment of clinical characteristics of rheumatoid arthritis related interstitial lung diseases

INTRODUCTION AND AIM: Rheumatoid Arthritis (RA) is the most common inflammatory arthritis in Turkey, with a prevalence of 0.2-1%. Approximately 10-40% of patients diagnosed with RA have RA related interstitial lung disease(RA-ILD). RA-ILD is a factor that negatively affects mortality and the development of this disease can be insidious. Generally accepted evidence-based recommendations and algorithms are not fully available for the follow-up and treatment of RA-ILD Therefore, we wanted to retrospectively review the clinical features of patients evaluated for RA-ILD and the methods used in our treatment. MATERIALS AND METHODS: This study included 87 patients who were admitted to Sakarya University Training and Research Hospital Internal Medicine Department, Rheumatology Clinic and evaluated by a pulmonologist or radiologist in terms of RA-ILD between September 2018 and August 2019. In this retrospective, cross-sectional, descriptive study, the non-parametric tests were used since the number of patients in the RA-ILD group was low. While Mann Whitney U test was used for numerical variables, Fisher's exact chi-square test was used for categorical variables. Numerical variables were presented as median values [width between quarters] and categorical variables were presented as frequency (% percentage). A P - value <0.05 was considered statistically significant. Analyses were performed using IBM SPSS 23 statistical software. RESULTS: Out of 87 patients the 8 of them (while 4 being female and 4 being male) were confirmed with RA-ILD. Of these patients, 2 were compatible with nonspecific interstitial pneumonia, 5 with regular interstitial pneumonia and 1 with RA-related nodule. In the presence of cellophane ral, the probability of RA-ILD was found to be 6.9 times higher (95% CI: 1.485-32.07) (p = 0.021). Residual volume (p = 0.018), total capacity (p = 0.019), and carbon monoxide diffusion capacity (p = 0.063) were found to be lower in the group with ILD compared to the other group. 5 of 8 patients diagnosed with RA-ILD used methotrexate before being diagnosed. In 3 of them, methotrexate was stopped and rituximab was started, in one patient, leflunomide was stopped and rituximab was started, in one patient, azathioprine was stopped and rituximab was started. While 1 patient was taking oral methotrexate, his clinic was considered stable and the subcutaneous methotrexate was started. CONCLUSION: In order to not to be late in the diagnosis of RA-ILD, which increases mortality and may be insidious, RA patients should be checked once a year with carbon monoxide diffusion capacity and spirometric function tests especially if there are existence of risk factors such as presence of cellophane ral, anti-CCP, rheumatoid factor positivity, smoking, male sex and being elderly. If necessary, further investigations such as high resolution computed tomography should be requested. The relationship of methotrexate, which is frequently used in RA, with RA-ILD is controversial. The clinician should adjust the treatment according to the patient's clinic and medical history. Rituximab therapy has been found to be successful for severe refractory RA-ILD in small case series. More randomized and controlled studies are needed for a generally accepted option in the treatment of RA-ILD. Keywords: Rheumatoid Arthritis, Interstitial Lung Disease, Methotrexate, Rituximab, High Resolution Computer Tomography, DLCO-SFT