Abstract
This cohort study aims to examine the clinical characteristics of idiopathic inflammatory myopathies (IIM) combined with pulmonary infection in hospitalized patients. Additionally, a new prediction model has been developed to evaluate the risk . One retrospective set (N = 371) was conducted to develop a predictive model. The clinical, radiological and laboratory features were collected and subjected to logistic regression analyses. The predictive model was displayed as a nomogram, which was externally validated in an independent set (N = 124). In the IIM patients with pneumonia, 100 strains of pathogenic bacteria were found, with fungal infections accounting for the majority. The novel nomogram model, which included the following parameters: age, combined ILD, albumin, lymphocyte count, C-reactive protein, and fibrinogen, was constructed successfully. The model had the AUC of 0.792 (95% CI: 0.744-0.839) and a C-index of 0.792 (95% CI: 0.744 - 0.839). It maintained good calibration values with an AUC of 0.744 (95% CI: 0.640 - 0.848) in the external validation set. This new nomogram shown high predictive performance in diagnosing IIM paired with pulmonary infection. This novel nomogram model was developed from a retrospective study and externally validated in an independent set based on six easily accessible clinical variables, and it exhibited good diagnostic performance.