Study on the Red Blood Cell Distribution Width in Connective Tissue Disease Associated with Interstitial Lung Disease
Background. Connective tissue disease (CTD) associated with interstitial lung disease (ILD) affects the lungs and can lead to considerable morbidity and shortened survival. Red blood cell distribution width (RDW) is a readily available parameter that is routinely reported with complete blood cell count (CBC) This study aimed to investigate the predictive value of RDW in CTD-ILD. Methods. A retrospective analysis was performed on 180 patients with CTD-ILD and 202 patients with CTD but without ILD between April 2016 and December 2018. Baseline demographics, laboratory results, imaging examinations, and results of ultrasound scans were analysed. Results. In comparison with patients without ILD, patients with CTD-ILD displayed a larger RDW (14.65 ± 2.08 vs. 14.17 ± 1.63, P=0.002), and RDW shared positive relationships with pulmonary artery systolic pressure (r = 0.349; P<0.001), length of hospital confinement (r = 0.172; P=0.022), and hospitalisation expenses (r = 0.158; P=0.037). Multivariate logistic regression analysis showed that RDW (odds ratio (OR): 1.232, 95% confidence interval (CI): 1.053–1.422, P=0.009), IgG (OR: 1.103, 95% CI: 1.051–1.159, P<0.001), and age (OR: 1.032, 95% CI: 1.010–1.054, P=0.004) are independent predictors of CTD-ILD risk. The optimal cut-off value of RDW for predicting CTD-ILD was 14.85%, with a sensitivity and a specificity value of 41.2% and 75.2%, respectively. Conclusions. RDW was significantly increased in patients with CTD-ILD under various CTD backgrounds and may be a promising biomarker that may help physicians predict CTD-ILD risk.