Reassessment and stratification of risk factors for postoperative pneumonia following gastrectomy in the minimally invasive surgery era: A large contemporary cohort study.

Background

Postoperative pneumonia is an important complication following gastrectomy. While several risk factors have been reported, most evidence is derived from small cohorts predating population aging or the minimally invasive surgery (MIS) era. Therefore, we aimed to reassess the risk factors in a large contemporary cohort and identify modifiable factors for postoperative pneumonia.

Methods

We retrospectively analyzed 1,379 patients who underwent curative gastrectomy in 2012-2025. Postoperative pneumonia was defined as Clavien-Dindo grade ≥ II. Risk factors for postoperative pneumonia were reassessed using multivariate regression analysis. Patients were stratified into three groups (low-, intermediate-, and high-risk groups) based on the number of risk factors, and the incidence of postoperative pneumonia was compared. Subgroup analyses were age-stratified (≥75 vs. <75 years).

Results

Postoperative pneumonia occurred in 81 patients (5.9%). Multivariate analysis identified age ≥ 75 years, male sex, prognostic nutritional index < 45, and total or proximal gastrectomy as risk factors, whereas perioperative oral care and minimally invasive surgery were associated with a decreased risk. Risk stratification analysis revealed a stepwise increase in postoperative pneumonia incidence with increasing risk factors (2.0%, 6.9%, and 27.3% in the low-, intermediate-, and high-risk groups, respectively; p for trend = 0.003). Subgroup analysis revealed the risk factor differences between older and younger patients for postoperative pneumonia.

Conclusions

Previously established risk factors for postoperative pneumonia remain relevant in the minimally invasive surgery era and demonstrate a cumulative effect. Postoperative pneumonia incidence following gastrectomy may be reduced by preoperative interventions for modifiable factors.