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

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