Background: Secondary organizing pneumonia (OP) is common in COVID-19 pneumonia. Patients with COVID-19 pneumonia who are complicated with OP may be associated with worse outcomes. This retrospective study aimed to identify risk factors associated with OP in patients with COVID-19 pneumonia and to compare clinical outcomes between patients with and without OP.

Methods: Hospitalized patients with COVID-19 pneumonia from July to September 2021 were included. We performed univariable and multivariable regression analysis to identify variables associated with OP in COVID-19 pneumonia patients. Multivariable Cox proportional hazard model was performed to evaluate the association of OP and 90-day mortality.

Results: Of 666 COVID-19 pneumonia patients, 53 (8%) developed OP. Factors associated with increased risk of OP including age groups 50-70 and >70 years (adjusted odds ratio [aOR]=3.87, 95% CI 1.24-12.11, p=0.02 and aOR=5.74, 95% CI 1.80-18.27, p=0.003), a history of diabetic mellitus (DM) (aOR=2.37, 95% CI 1.27-4.44, p=0.01), and oxygen saturation (SpO2) on admission <88% (aOR=4.52, 95% CI 1.22-16.67, p=0.02). Patients with COVID-19 pneumonia complicated with OP had higher 90-day mortality (adjusted hazard ratio=3.40, 95% CI 1.68-6.92, p=0.001) compared to those without OP. In addition, OP was associated with increased risk of respiratory failure, acute kidney injury, secondary bacterial and fungal infections, pneumothorax, pneumomediastinum, and pulmonary embolism.

Conclusion

Age ?50 years, a history of DM, and hypoxemia on admission (SpO2 <88%) were associated with increased risk of OP in patients with COVID-19 pneumonia. OP was associated with increased 90-day mortality and complications.