Pre-operative Neutrophil-to-Lymphocyte Ratio is Associated with Post-operative Opioid Requirements and Length of Stay after Thoracotomy

BACKGROUND: Surgical pain and prolonged hospital length of stay (LOS) affect a large proportion of patients after thoracotomy. Inflammation plays a crucial role in the mechanism and progression of pain and the outcomes. AIM: The objective of this study was to investigate the association between the pre-operative neutrophil-to-lymphocyte ratio (NLR) and post-operative pain and LOS in patients undergoing thoracotomy. METHODS: This was a retrospective, observational study on 157 patients who underwent thoracotomy under general anesthesia. We classified the subjects into two study groups: Group with for patients with NLR <2 and Group 2 for NLR ≥2. We measured the post-operative pain by gathering the data of post-operative opioid needs. We used Pearson’s and Spearman’s correlation tests to assess the association of the parameters. RESULTS: The mean of total oral morphine equivalent in the first 48 h following thoracotomy in Group 1 was 140.8 ± 60.4 mg compared to Group 2’s 109.7 ± 55.8 (p < 0.05). The median hospital’s LOS was longer in Group 2 compared to Group 1 (7 vs. 10, p < 0.001). We found a weak positive correlation between pre-operative NLR (R = 0.267, p = 0.002) and post-operative opioid requirements, and a weak positive correlation between pre-operative NLR and the hospital’s LOS (R = 0.345, p < 0.001). CONCLUSION: Pre-operative NLR correlates with post-operative opioid requirements and the time hospital’s LOS in patients who underwent elective thoracotomy.