Predicting risk factors of combined pulmonary infection in patients with idiopathic inflammatory myopathies

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.