Background: Secondary pulmonary infection (SPI) is a severe complication in patients with COVID-19.

Objective: To investigate the risk factors, mortality rates, and complications associated with SPI in hypoxemic COVID-19 pneumonia patients.

Materials and Methods: A retrospective cohort study was conducted at Saraburi Hospital, analyzing medical records of 512 hospitalized COVID-19 patients. The Fine-Gray model identified risk factors for SPI.

Results: SPI was diagnosed in 25.4% of hypoxemic COVID-19 pneumonia patients. SPI patients (mean age of 65.9±15.1 years) had higher inflammation biomarkers, increased in-hospital mortality (IHM), and more complications than non-SPI patients. The primary pathogens causing IHM were gram-negative bacteria in 59.23%. Risk factors for SPI included age of 65 years or older (sHR 1.52; 95% CI 1.03 to 2.25; p=0.032), obesity (sHR 1.52; 95% CI 1.04 to 2.23; p=0.028), invasive mechanical ventilation (sHR 2.87; 95% CI 1.64 to 5.02; p<0.001), lactate dehydrogenase (LDH) level of 520 U/L or more (sHR 2.37; 95% CI 1.69 to 3.33; p=0.027), and catheter-related bloodstream infection (sHR 2.74; 95% CI 1.71 to 4.40; p<0.001). SPI patients had an IHM rate of 74.62%. Multivariable analysis showed higher IHM in SPI patients (aOR 5.29; 95% CI 2.70 to 10.36) compared to non-SPI patients.

Conclusion: SPI is a common and harmful complication in hypoxemic COVID-19 pneumonia. Older age, obesity, invasive mechanical ventilation, elevated LDH levels, and catheter-related bloodstream infection are significant risk factors for SPI. Early detection and prevention strategies are crucial to mitigate the short-term consequences of SPI in COVID-19 patients.

Keywords: COVID-19; Secondary pulmonary infection; Mortality; Risk factors

DOI: 10.35755/jmedassocthai.2023.07.13765

Received 6 February 2023 | Revised 26 May 2023 | Accepted 7 June 2023