MUC5AC and Pleural effusion: In addition, ROC curves were plotted for different risk factors in this study, and the results showed that the increased levels of MUC5AC in sputum, LDH and immunoglobulin lgM in serum, NLR, maximum temperature, and the occurrence of pleural effusion were all effective predictors for early fiberbronchoscopy treatment for MPP children with lobar pneumonia.