Clinical characteristics of patients with connective tissue disease-related interstitial lung disease: a retrospective analysis

Introduction Interstitial lung disease is one of the most critical manifestations of connective tissue diseases that may cause morbidity and mortality. This study aimed to evaluate the clinical and demographic characteristics and treatment of the patients with connective tissue disease-related interstitial lung disease. Method This retrospective observational study included patients from the Gulhane Rheumatology Interstitial Lung Disease cohort between October 2016 and June 2023. The patients were assessed retrospectively. Results A total of 173 patients were included in the study with a mean age of 63.4 +/- 11.9 years. The frequencies of CTD were 34.1% Sjogren's syndrome, 30.1% rheumatoid arthritis, 25.4% systemic sclerosis, 5.8% undifferentiated connective tissue disease, 2.9% idiopathic inflammatory myositis, 1.2% mixt connective tissue disease, and 0.6% systemic lupus erythematosus in decreasing frequencies. Nonspecific interstitial pneumonia, which was the most common interstitial lung disease pattern in 103 (59.5%) patients, was most frequent among patients with SS and SSc (p < 0.001 vs. p < 0.001). Usual interstitial pneumonia was most frequent among patients with RA (p < 0.001). All patients received immunosuppressive treatment, most commonly azathioprine. 57.2% were using immunosuppressives for ILD. Six patients had mortality, and infections were the leading cause. Conclusions As a critical manifestation of connective tissue diseases, immunosuppressive treatment is indispensable in the management of interstitial lung diseases especially those at an increased risk for progression. The treatment approaches should be assessed in a patient-based way. The patients under immunosuppressive treatment should be cautiously followed for infections.