Impact of prognostic nutritional index on postoperative outcome of acute empyema.

Background: The prognostic nutritional index (PNI) is a useful prognostic index for postoperative outcomes in many fields. We investigated the usefulness of the PNI as a prognostic biomarker of 1-year postoperative survival for acute empyema. Methods: The subjects of this retrospective study were patients who underwent surgery for acute empyema at NHO Iwakuni Clinical Center between November 2009 and March 2022, and they were divided into two groups: those who survived after surgery (survival group) and those who died from all-cause within 1 year after surgery (death within 1-year group). The preoperative PNI calculated within 3 days before surgery and the postoperative PNI calculated 7 days after surgery were compared between the two groups. An appropriate cutoff value of the preoperative PNI was set for the 1-year survival analyses after surgery. Results: A total of 75 patients were included. The preoperative PNI was significantly lower in the death within 1-year group (n=13) than in the survival group (n=62) (P=0.01) and was significantly associated with prolonged postoperative hospital stay (r=-0.51, P<0.001). Patients with preoperative PNI >29.3 had significantly better 1-year survival than those with an index ≤29.3 (P=0.02). In patients with a preoperative PNI ≤29.3, patients who had a higher postoperative index than the preoperative index had as good 1-year survival as those with preoperative PNI >29.3 (P=0.19). Conclusions: The PNI may be a predictor of postoperative prognosis and an indicator of postoperative treatment efficacy in acute empyema.