Pulmonary Embolism Risk Factors

Guideline-Established Risk Factors for PE

• The European Society of Cardiology identifies lower limb fractures as a strong risk factor for PE (OR >10) 1
• The European Society of Cardiology identifies hip or knee replacement as a strong risk factor for PE (OR >10) 1
• The European Society of Cardiology identifies major trauma as a strong risk factor for PE (OR >10) 2
• The European Society of Cardiology identifies myocardial infarction within 3 months as a strong risk factor for PE (OR >10) 1
• The European Society of Cardiology identifies previous VTE as a strong risk factor for PE (OR >10) 1
• The European Society of Cardiology identifies spinal cord injury as a strong risk factor for PE (OR >10) 1, 3, 2
• The European Society of Cardiology identifies infection (specifically pneumonia, urinary tract infection, and HIV) as a moderate risk factor for PE (OR 2-9) 1, 3, 2
• The European Society of Cardiology identifies cancer (highest risk in metastatic disease) as a moderate risk factor for PE (OR 2-9) 2
• The European Society of Cardiology identifies chemotherapy as a moderate risk factor for PE (OR 2-9) 1
• The European Society of Cardiology identifies central venous catheters as a moderate risk factor for PE (OR 2-9) 1
• The European Society of Cardiology identifies autoimmune diseases as a moderate risk factor for PE (OR 2-9) 1, 3
• The European Society of Cardiology identifies bed rest >3 days as a weak risk factor for PE (OR <2) 4
• The European Society of Cardiology identifies diabetes mellitus as a weak risk factor for PE (OR <2) 1
• The European Society of Cardiology identifies arterial hypertension as a weak risk factor for PE (OR <2) 2
• The European Society of Cardiology identifies obesity as a weak risk factor for PE (OR <2) 1, 3

Guideline Recommendations

• The European Society of Cardiology and European Respiratory Society recommend following their guidelines for PE risk stratification, which do not include mycoplasma as a recognized risk factor 4, 1, 3, 2

Pneumonia and Pulmonary Embolism Association

Clinical Guidelines and Evidence

• Clinical guidelines recommend considering pulmonary embolism in patients with a history of DVT, pulmonary embolism, immobilization in the past 4 weeks, or malignant disease 5
• Pneumonia is listed among noninfectious extrapulmonary complications that can delay radiographic clearing in pneumonia patients, alongside pulmonary embolus with infarction 6

Risk Stratification and Prevention

• Immobilized pneumonia patients require DVT prophylaxis with subcutaneous anticoagulants or intermittent pneumatic compression 7
• Stroke patients with pneumonia face particularly high risk, as both conditions independently increase PE risk and often coexist with immobility 8
• Implement DVT prophylaxis with anticoagulants or mechanical compression for immobilized patients 7
• Promote early mobilization when medically feasible 8, 7

Diagnostic Considerations

• PE should be considered among the differential diagnoses for noninfectious illnesses that can mimic or complicate pneumonia 6

Pulmonary Embolism Risk Assessment: Guideline‑Defined Factors and the Position of Sarcoidosis

Established Guideline‑Based PE Risk Factors (ESC/ERS 2019)

• Active malignancy (especially pancreatic, hematologic, lung, gastric, or brain cancers) confers a moderate‑strength risk for pulmonary embolism (odds ratio 2–9) in adult patients according to the European Society of Cardiology/European Respiratory Society 2019 guidelines. 9
• Acute infections such as pneumonia, urinary‑tract infection, or HIV increase PE risk at a moderate level (OR 2–9) as outlined in the ESC/ERS 2019 recommendations. 9
• Recent major surgery, major trauma, or prolonged immobilization, a prior venous thrombo‑embolism, and active cancer are listed as standard PE risk factors that should be screened for in any patient (including those with sarcoidosis) per the ESC/ERS 2019 guideline. 9
• Hormonal therapies—including combined oral contraceptives and hormone‑replacement therapy—are recognized as additional moderate‑strength PE risk factors in the ESC/ERS 2019 document. 9
• Clinical decision‑rule scores (e.g., Wells or Geneva) are recommended over isolated D‑dimer testing for estimating PE probability in patients with inflammatory conditions such as sarcoidosis, because D‑dimer may be elevated by inflammation alone (ESC/ERS 2019). 9

Sarcoidosis in Major Cardiovascular Guidelines

• The 2004 European Society of Cardiology guideline mentions sarcoidosis only under “miscellaneous” causes of pulmonary hypertension and does not list it as an independent risk factor for pulmonary embolism. 10

Evidence‑Based Risk Factors for Pulmonary Embolism

Cardiorespiratory Disorders

• Congestive heart failure, congenital heart disease, and irreversible airway disease increase the risk of pulmonary embolism by promoting venous stasis. 11

Post‑operative Critical Care

• Admission to postoperative intensive‑care units markedly raises pulmonary embolism risk because patients are simultaneously exposed to immobility, systemic inflammation, and invasive procedures. 11

Age‑Related Risk

• Individuals older than 40 years experience an exponential rise in pulmonary embolism incidence, reflecting the cumulative effect of age‑related comorbidities and physiological changes. 11

Hormonal Factors

• Use of combined oral contraceptives elevates the risk of venous thromboembolism 2‑ to 6‑fold; third‑generation formulations (containing desogestrel or gestodene) confer a higher risk than second‑generation agents. 12
• Pregnancy and the postpartum period increase pulmonary embolism risk approximately five‑fold compared with non‑pregnant women of similar age; the majority of deep‑vein thromboses occur ante‑partum and most pulmonary emboli occur postpartum. 12

Immobilisation

• Prolonged bed rest of more than three days, as well as short‑term immobilisation lasting about one week, predisposes patients to venous thromboembolism through venous stasis. 12

Inherited and Acquired Thrombophilia

• Genetic abnormalities such as the prothrombin 20210A mutation, antithrombin III deficiency, protein C deficiency, protein S deficiency, and hyperhomocysteinemia are recognized contributors to pulmonary embolism risk. 12
• Evaluation for thrombophilia is recommended in patients with unexplained thrombotic events before age 40, recurrent deep‑vein thrombosis or pulmonary embolism, or a strong family history of thrombosis. 12

Epidemiology of Unexplained Cases

• Approximately 50 % of pulmonary embolism episodes occur in the absence of any classical predisposing factor, underscoring the need for high clinical suspicion even when known risk factors are not present. 12

Preventability of Pulmonary Embolism through Risk Stratification and Thromboprophylaxis

Evidence of Preventability

• The European Society of Cardiology (ESC) states that venous thromboembolism, including pulmonary embolism, “may be lethal… but it is also often preventable.” 13

Efficacy of Thromboprophylaxis

• Antithrombotic prophylaxis markedly lowers the risk of peri‑operative VTE; the highest incidence occurs in the first two postoperative weeks and remains elevated for 2–3 months thereafter. 14
• Extending the duration of thromboprophylaxis after major orthopaedic or cancer surgery further reduces VTE incidence. 14

Risk‑Stratification Guidelines (ESC/ERS 2019)

• The ESC/European Respiratory Society (ERS) guidelines classify risk factors by odds‑ratio strength, enabling targeted prophylaxis. 15

Strong risk factors (OR > 10) – aggressive prophylaxis required

• Lower‑limb fractures. 15
• Hip or knee replacement surgery. 15
• Major trauma. 15
• Myocardial infarction within the preceding 3 months. 15
• Prior VTE episode. 15
• Spinal cord injury. 15

Moderate risk factors (OR 2–9) – prophylaxis recommended in appropriate contexts

• Active malignancy (especially pancreatic, hematologic, lung, gastric, brain). 15
• Ongoing chemotherapy. 15
• Significant infection (e.g., pneumonia, urinary‑tract infection, HIV). 15
• Presence of a central venous catheter. 15
• Use of oral contraceptives or hormone‑replacement therapy. 15
• Post‑partum period. 15

Weak risk factors (OR < 2) – contribute to cumulative risk

• Bed rest longer than 3 days. 15
• Obesity. 15
• Prolonged immobility (e.g., long‑duration air travel). 15
• Age > 40 years, with risk roughly doubling each decade. 14

Prophylaxis Duration Recommendations

• In high‑risk surgical patients, thromboprophylaxis should continue beyond hospital discharge, particularly after major orthopaedic procedures. 14

Clinical Implementation Algorithm (ESC/ERS)

• Systematic identification of all patient‑specific risk factors using the ESC/ERS stratification framework is the first step in prevention. 15