Male Sex, Early Postoperative C-Reactive Protein and Prolonged Hospital Stay After Lung Resection in Older Patients: A Retrospective Cohort Study

Background/Objectives: Older patients make up a growing share of the lung-resection workload, and C-reactive protein measured in the first days after operation is used to judge recovery. Whether the same concentration means the same thing in older men and older women is not established. Methods: We analysed 724 lung resections in 716 patients from VitalDB, an open perioperative dataset from a Korean tertiary hospital; 313 (43.2%) were aged 65 years or older. The primary outcome was a postoperative stay of 7 days or longer. Older general surgical patients from the same institution served as an age-matched negative control. Results: Among patients aged 65 or older, prolonged stay occurred in 55 of 192 men (28.6%) and 10 of 121 women (8.3%), adjusted odds ratio 3.031 (95% CI 1.425–6.446, p = 0.0040). Median day 1 C-reactive protein was 51.9 mg/L in older men and 27.4 mg/L in older women, adjusted ratio of geometric means 1.825 (1.593–2.090, p = 1.8 × 10−16). C-reactive protein predicted prolonged stay unadjusted (1.594 per doubling, 1.292–1.967) but not once sex entered the model (0.865, 0.691–1.084, p = 0.208), an interval that remains compatible with a modest association in either direction. In 1635 older general surgical patients, neither effect was present (0.863, p = 0.302; 1.238, p = 0.163). The sex-by-age interaction was not significant (p = 0.519). Conclusions: In older patients undergoing lung resection, men mount a larger early inflammatory response than women to comparable operations and are three times as likely to stay a week or longer, an association absent from older general surgical patients at the same institution. In this dataset and with the measured covariates, C-reactive protein on the first postoperative day was not independently associated with prolonged hospital stay after adjustment for sex and the other available factors; with 113 events, this does not establish absence of prognostic value. These data do not derive, validate, or justify sex-specific C-reactive protein thresholds, and none is proposed.