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

Dong Hyuck Kim, H. Seo, Yoonkyung Lee, I. Kim, Minsoo Kim, Y. H. Lim, Jung Eun Kim, S. Choi et al.

Anesthesia and Pain Medicine, 2026

Abstract

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…

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Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence.

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