Risk factors for venous thromboembolism in patients with pneumonia in the pre-COVID-19 era: a meta-analysis and systematic review

Background: Elevated risk of venous thromboembolism (VTE) in patients with coronavirus disease 2019 (COVID-19) pneumonia has been recognized, while the risk factors associated with VTE in patients with non-COVID-19 pneumonia remain to be defined. This study aimed to conduct a meta-analysis and systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify potential risk factors for VTE in patients with pneumonia from the pre-COVID-19 era.

Methods: PubMed, EMBASE, and Cochrane Library were searched. Two reviewers performed screening, full-text review, and extraction. Risk factors and odds ratio (OR) were estimated.

Results: Of 595 articles identified, six studies were included. Pooled analysis suggested that age ≥60 years [OR =2.75, 95% confidence interval (CI): 2.55-2.97, P<0.001], mechanical ventilation (MV) (OR =9.48, 95% CI: 8.24-10.91, P<0.001), hypertension (OR =1.41, 95% CI: 1.09-1.83, P=0.010), diabetes (OR =1.49, 95% CI: 1.36-1.64, P<0.001), heart failure (OR =3.15, 95% CI: 1.05-9.41, P=0.040) and cancer (OR =2.86, 95% CI: 2.07-3.95, P<0.001) were associated with higher risk for deep vein thrombosis in patients with pneumonia. While age ≥60 years (OR =2.46, 95% CI: 2.21-2.73, P<0.001), bacterial pneumonia (OR =3.80, 95% CI: 1.65-8.73, P=0.002), hyperlipidemia (OR =1.55, 95% CI: 1.00-2.41, P=0.049), heart failure (OR =2.70, 95% CI: 2.05-3.56, P<0.001), chronic obstructive pulmonary disease (OR =4.73, 95% CI: 3.11-7.17, P<0.001) and cancer (OR =2.90, 95% CI: 2.39-3.53, P<0.001) were risk factors for pulmonary embolism in patients with pneumonia.

Conclusions: Patients with non-COVID-19 pneumonia, particularly those with advanced age, MV, cardiovascular comorbidities or cancer, warrant individualized management during hospitalization. Our findings could contribute to refining risk prediction models and further risk stratification for VTE in patients with pneumonia in clinical practice.