Changes in postoperative pneumonia incidence after the pandemic: a retrospective observational study using a common data model

초록

Background: The coronavirus disease 2019 (COVID-19) pandemic has profoundly influenced surgical practice and perioperative care, but its impact on postoperative pneumonia incidence remains unclear. Methods: We conducted a retrospective cohort study using the Observational Medical Outcomes Partnership–Common Data Model databases from 17 Korean hospitals. Based on the inpatient surgery date, patients were classified into prepandemic (January 2018–December 2019) and postpandemic groups (January 2020–December 2021). Postoperative pneumonia was identified within 30 days after surgery. Logistic regression analysis assessed the independent effects of the pandemic, age, anesthetic technique, and their interaction. Results: The overall incidence of postoperative pneumonia per 10,000 persons changed slightly from 12.38 prepandemic to 12.99 postpandemic (+4.94%). Younger patients (< 70 years) demonstrated decreased incidence (8.47→7.97, −5.81%), whereas older patients (≥ 70 years) demonstrated increased incidence (28.97→31.97, +10.36%). Considerable interhospital variation was observed, with some hospitals reporting increases exceeding 100%, while others reporting declines exceeding 80%. Overall postoperative pneumonia risk was similar between the pre-and postpandemic periods (odds ratio [OR], 0.893; 95% confidence interval [CI], 0.787–1.015). Older age (≥ 70 years) was strongly associated with higher risk (OR, 2.816; 95% CI, 2.383–3.328), and a significant postpandemic×age interaction indicated that older patients were disproportionately affected (OR, 1.385; 95% CI, 1.145– 1.675). Conclusions: The COVID-19 pandemic did not substantially change the overall incidence of postoperative pneumonia, although variations existed across hospitals and age groups. Older age remained the strongest risk factor. Further studies are warranted to clarify the underlying causes and optimize perioperative infection control. © The Korean Society of Anesthesiologists, 2026.

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