Abstract
Objective The aim of this study was to evaluate the diagnostic and prognostic value of red blood cell distribution width (RDW) in patients with connective tissue disease-associated interstitial lung disease (CTD-ILD). Methods We retrospectively reviewed 213 CTD-ILD patients and 97 CTD patients without ILD from February 2017 to February 2020. Hospital and office records were used as data sources. CTD-ILD patients were followed up. Results Patients with CTD-ILD had significantly higher RDW than those with CTD without ILD (p < 0.001). The area under the receiver operating characteristic curve (AUROC) of RDW for discriminating CTD-ILD from CTD without ILD was 0.64 (95% CI: 0.57-0.70, p < 0.001). The cutoff value of RDW for discriminating CTD-ILD from CTD without ILD was 13.95% with their corresponding specificity (55.9%) and sensitivity (70.1%). Correlation analyses showed that the increased RDW was significantly correlated with decreased DLCO%predicted (r = −0.211, p = 0.002). Cox multiple regression analysis indicated that RDW (HR = 1.495, p < 0.001) was an independent factor in the survival of CTD-ILD. The best cutoff value of RDW to predict the survival of patients with CTD-ILD was 14.05% (AUC = 0.78, 95% CI: 0.72-0.84, p < 0.001). The log-rank test showed a significant difference in survival between the two groups (RDW > 14.05% and RDW < 14.05%). Conclusion RDW was higher in CTD-ILD patients and had a negative correlation with DLCO%predicted. RDW may be an important serum biomarker for severity and prognosis of patients with CTD-ILD.
Highlights
Interstitial lung diseases (ILDs) are a group of diseases in which characterized by varying degrees of inflammation and fibrosis of lung parenchyma and interstitium
ILD is strongly associated with various connective tissue diseases (CTDs), such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), systematic vasculitis, polymyositis/dermatomyositis (PM/DM), Sjögren’s syndrome (SS), mixed CTD (MCTD), and undifferentiated CTD (UCTD) [1, 2]
Male gender, smoking history, and older age were more common in the connective tissue disease-associated interstitial lung disease (CTD-ILD) group (p = 0:001, p = 0:001, and p < 0:001, respectively)
Summary
Interstitial lung diseases (ILDs) are a group of diseases in which characterized by varying degrees of inflammation and fibrosis of lung parenchyma and interstitium. The presence of ILD is common in CTD, which is associated with reduced quality of life and a leading cause of mortality [3]. It has been reported that five-year survival was 80% and median survival was approximately 12.6 years in a cohort of CTD-ILD [4], progression and prognosis of CTD-ILD vary widely between CTD subtypes. In cases of rapidly progressing and severe CTD-ILD, sensitive recognition and appropriate treatment of CTD-ILD could be critical to improve the clinical outcome of these patients [5]. There is a great need for the identification of biomarkers that could help reflect the severity and prognosis of CTD-ILD.
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