Association of Preoperative Neutrophil-to-Lymphocyte Ratio and Immature Granulocytes with Postoperative Pain After Laparoscopic Sleeve Gastrectomy: A Retrospective Cohort Study

Background/Objectives: Systemic inflammation may influence postoperative pain, but simple preoperative markers of pain risk are lacking in bariatric surgery. We examined whether the preoperative neutrophil-to-lymphocyte ratio (NLR) and immature granulocyte percentage (IG%) are associated with pain severity after laparoscopic sleeve gastrectomy (LSG). Methods: In this single-center retrospective cohort, records of 81 adults undergoing LSG were reviewed. Pain was rated on the 11-point numeric rating scale (NRS) in the recovery unit, at 24 h, and at 3 months. As NRS is ordinal, associations were assessed with Spearman correlation, covariate-adjusted ordinal logistic (proportional-odds) regression, NLR tertiles with a trend test, and receiver-operating-characteristic (ROC) analysis. Results: Preoperative NLR correlated positively with recovery unit NRS (rho = 0.36), 24 h NRS (rho = 0.37), and 3-month NRS (rho = 0.61; all p ≤ 0.001). After multivariable adjustment, log-NLR remained independently associated with recovery unit pain (odds ratio 6.1) and 24 h pain (odds ratio 8.1; both p < 0.001), with a graded relationship across tertiles (p for trend ≤ 0.020). For moderate-to-severe recovery unit pain, NLR discriminated with an area under the curve of 0.79 (optimal cutoff > 1.73). Neither IG% nor absolute IG was associated with any pain outcome (all p > 0.110). Conclusions: Higher preoperative NLR was independently and dose-dependently associated with greater early postoperative pain after LSG, whereas IG showed no association. NLR is a routinely available, essentially cost-free value that may help flag patients at risk of more severe early postoperative pain; prospective validation is warranted.