CRP and Pleural effusion: Existing prediction models for refractory MPP (RMPP), severe MPP (SMPP), and necrotizing MPP (NMPP) have identified several independent risk factors, including peak body temperature, pleural effusion, extrapulmonary complications, neutrophil ratio, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), D-dimer, lactate dehydrogenase (LDH), and albumin (ALB) (12–14).