Preoperative Fibrinogen-to-Prealbumin Ratio and in-Hospital Postoperative Pneumonia After Minimally Invasive McKeown Esophagectomy for Esophageal Squamous Cell Carcinoma: A Retrospective Cohort Study with Infection Phenotype Profiling.

Background: Postoperative pneumonia (PP) after esophagectomy arises from interacting pulmonary, aspiration, airway-protection, perioperative-care, and host-response pathways. Whether the preoperative fibrinogen-to-prealbumin ratio (FPR), a marker integrating inflammatory-coagulative activity and nutritional-inflammatory reserve, is associated with in-hospital PP after minimally invasive McKeown esophagectomy remains uncertain. Methods: Using routinely collected electronic medical-record data, consecutive patients with pathologically confirmed esophageal squamous cell carcinoma (ESCC) who underwent elective minimally invasive McKeown esophagectomy from January 2023 to December 2025 were retrospectively analyzed. FPR was expressed on the ×1000 scale and analyzed continuously per 1-unit and per 1-standard-deviation (SD) increase. The primary endpoint was in-hospital PP. Sequential multivariable logistic regression, restricted cubic splines, infection-phenotype and microbiological description, multicollinearity diagnostics, and clinically defined sensitivity analyses were performed. A complete-case 30-day PP analysis was included as a sensitivity analysis. Selectively performed airway and swallowing assessments were analyzed descriptively only. Results: Among 437 patients, 139 (31.8%) developed in-hospital PP. In the primary fully adjusted clinical model, each 1-unit increase in FPR ×1000 was associated with higher odds of PP (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.23-1.41; P<0.001); the OR per 1-SD increase was 4.40 (95% CI 3.09-6.29; P<0.001). Restricted cubic spline analysis supported an overall graded association (P for overall <0.001; P for non-linearity=0.162). Results remained consistent in the complete-case 30-day analysis and other sensitivity analyses. Median PP onset was postoperative day 5; 25.2% of cases were classified as aspiration-likely, and 44.7% of cultured cases were culture positive. Conclusion: Higher preoperative FPR was associated with in-hospital PP after minimally invasive McKeown esophagectomy for ESCC. These single-center retrospective findings are hypothesis-generating and do not establish causality or immediate clinical utility. Prospective multicenter and external validation is required before FPR is used for perioperative risk stratification.