F2 and heart failure: Thirdly, the model was validated using ROC curves, Harrell's C-index, calibration plots, DCA, and K-M curve.<h4>Result</h4>Eight predictive indicators were selected, including blood urea nitrogen, prothrombin time, white blood cell count, heart rate, the presence of comorbid interstitial lung disease, heart failure, and the use of antibiotics and bronchodilators.