Predictive Value of Preoperative Neutrophil-to-Lymphocyte Ratio, Platelet-to-Lymphocyte Ratio, and Serum Albumin for Postoperative Pneumonia after Thoracic Surgery

Abstract Background: Postoperative pneumonia (POP) is an important complication that occurs after thoracic surgeries and has been responsible for increased cases of morbidity and mortality. It is, therefore, important to identify those patients at high risk of developing it before the surgery, allowing for the implementation of preventive measures. Purpose: This study aimed at examining the predictive significance of preoperative platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and serum albumin level in relation to the potential occurrence of postoperative pneumonia in patients sought for thoracic surgery. Material and methods: The authors used a prospective cohort design to observe 287 patients who were to undergo thoracic surgery from January 2022 to December 2023. Blood samples for complete blood test and serum albumin were drawn not later than 48 hours prior to the operation. The diagnosis of postoperative pneumonia adhered to established diagnostic criteria. Results: Fifty-two patients developed postoperative pneumonia (cumulative incidence of 18.1%). The group of patients with POP was characterized by significantly higher NLR (4.8 ± 2.1 vs. 2.9 ± 1.3, p<0.001), higher PLR (134.7 ± 48.2 vs. 98.3 ± 35.6, p<0.001) and lower serum albumin levels (3.1 ± 0.6 vs. 3.7 ± 0.4, p<0.001). ROC analysis revealed the area under the curve for NLR, PLR, and serum albumin of 0.821, 0.764, 0.809 respectively. A combined score that covers all the three factors showed higher predictive significance (AUC 0.887). Conclusion: The author concluded that NLR, PLR, and serum albumin are significant predictors for postoperative pneumonia occurrence. The combined score can help recognize the patients at risk and apply effective treatment methods. Keywords: Neutrophil-to-lymphocyte ratio; Platelet-to-lymphocyte ratio; Serum albumin; Postoperative pneumonia; Thoracic surgery; Predictive marker