Predicting the risk of interstitial lung disease in patients with primary Sjögren's syndrome: Novel nomogram and elevated Th2 cells

Interstitial lung disease (ILD) is one of the most common pulmonary complications in patients with primary Sjögren’s syndrome (pSS). This study was performed to identify immunological risk factors of pSS-associated ILD (pSS-ILD) and to further establish and evaluate of nomograms predicting the risk of ILD in patients with pSS. A total of 622 patients with pSS (117 with ILD and 505 without lung involvement) and 166 healthy control subjects (HCs) were ultimately recruited to this retrospective study. Routine examination indicators, tumour markers and lymphocyte (LYMP) subpopulations were extracted. Simple and multiple logistic regressions analyses were performed to screen for independent predictors. Restricted cubic splines were used to examine associations of independent predictors with ILD, and a risk assessment model was constructed. A nomogram prediction model was developed, and receiver operating characteristic (ROC) curve analysis was performed to assess its performance. Univariate and multivariate logistic regression analyses showed that the older age, white blood cell (WBC) count, haemoglobin (HB) level, albumin (ALB) level, CA242 level, and the C-reactive protein (CRP)/LYMP ratio (CLR) were independent predictors of pSS-ILD in a linear manner, these factors were integrated and used to construct a nomogram prediction model. The model had clinical predictive value. In addition, the elevated Th2 cells proportion in pSS patients was significantly positively correlated with lung involvement, while it was negatively correlated with HB and ALB levels. Remarkably, the numbers of Th2 cells were correlated with the CLR in both pSS patients and those with pSS-ILD. Our novel ILD nomogram could be used to assess the risk of ILD in pSS patients with good discrimination ability. As well as, elevated peripheral blood Th2 cell levels may be related to ILD in patients with pSS.