Analysis of Clinical Characteristics of Connective Tissue Disease-Associated Interstitial Lung Disease in 161 Patients: A Retrospective Study

Objective: This study was conducted to retrospectively analyze the clinical characteristics of CTD-ILD patients to provide strategies for clinical management.Methods: This study collected and analyzed the clinical data and relevant examination results of 161 patients diagnosed with CTD-ILD between 01 January 2018 and 01 January 2021.Results: A total of 161 CTD-ILD patients, 74.53% were females and 25.47% were males, 32.92% were elderly and 67.08% were non-elderly. The main clinical symptoms of CTD-ILD patients were cough (44.72%), decreased activity tolerance (40.37%). RA-ILD was the most common one in the non-elderly and the elderly CTD-ILD patients (48.15% and 50.94%, respectively). Compared with non-elderly, elderly patients with CTD-ILD had a longer duration of CTD (p=0.04). However, fatigue (p=0.005), activity tolerance (p=0.029), the incidence of pulmonary diffusion dysfunction (p=0.047), and systemic immunoinflammatory index (SII, p=0.014) (platelet x NLR) were all decreased. The standard deviation of red blood cell distribution width (RDW) (p=0.024) and immunoglo-bulin (IgA) (p=0.033) was significantly increased. The smoking index was significantly higher in men than in women with CTD-ILD (p=0.000), but symptoms of reduced activity tolerance were less pronounced than in women (p<0.05). Elderly CTD-ILD patients (p=0.003) and women from non-elderly patients were prone to lower hemoglobin (p=0.000). Among the elderly, the lymphocyte ratio was more significantly elevated in female CTD-ILD patients than in males (p=0.018). In contrast, neutrophil to lymphocyte ratio (NLR) and SII were lower in female (p=0.038) than in male CTD-ILD patients (p=0.043).Conclusion: CTD-ILD mainly affects non-elderly and women. Age may not be involved with decreased activity tolerance and increased lung function impairment in CTD-ILD patients. However, the elderly patients with CTD-ILD, especially the elderly female patients with low inflammation levels and high immune disorders, have a poor prognosis.