The role of age in venous thromboembolism (VTE)
Venous thromboembolism (VTE) is a collective term for a blood clot that forms in a deep vein, most often in the leg (DVT), and a pulmonary embolism (PE), which occurs when a DVT breaks free and travels to the lungs. While PE can happen at any age, the risk significantly increases with advancing age. A Danish study found that the incidence of first-time PE increased across all adult age groups between 1999 and 2018, with the highest rates in those over 85. The reasons for this age-dependent risk are complex and multifaceted, involving a mix of inherent physiological changes and acquired risk factors common in later life.
Age-related physiological changes that increase risk
As people get older, their bodies undergo several changes that create a hypercoagulable (pro-clotting) state. This involves an imbalance in the body's natural coagulation and anticoagulation systems, where pro-clotting factors increase without a proportional rise in anti-clotting proteins.
- Changes in Coagulation Factors: The liver's production of certain coagulation proteins, such as Factor VIII and von Willebrand factor, increases with age. At the same time, the activity of the fibrinolytic system, which is responsible for breaking down clots, decreases. The result is a system that is more primed to form clots and less efficient at dissolving them.
- Endothelial Dysfunction: The cells lining the inside of blood vessels are called endothelial cells. As they age, they can become dysfunctional and inflamed. This process, known as endothelial senescence, contributes to a prothrombotic environment by promoting plaque buildup, increasing oxidative stress, and altering blood flow.
- Alterations in Blood Flow: Changes in the elasticity of blood vessels and other vascular alterations can affect blood flow. For older adults, especially those who are frail or have chronic diseases, blood circulation can slow down. Stagnant blood, particularly in the deep veins of the legs, is a primary component of Virchow's Triad, a classic model for thrombosis, and significantly increases the likelihood of a clot forming.
Age-associated comorbidities and lifestyle factors
Beyond direct physiological changes, older age is often accompanied by an increase in risk factors and medical conditions that contribute to VTE risk. These factors often compound the physiological changes already underway, creating a significantly elevated risk profile.
- Immobility and Hospitalization: Prolonged immobility is one of the most significant risk factors for VTE, and it becomes more common with age. Older adults are more likely to be hospitalized for medical conditions or surgery, or to have limited mobility at home due to frailty or degenerative diseases like stroke or osteoarticular processes. Bed rest, especially in the first few weeks, dramatically increases the risk of thrombosis.
- Cancer and Chronic Diseases: The incidence of cancer and other chronic conditions, including heart failure and chronic lung disease, rises with age. Cancer and cancer treatment are major risk factors for VTE, particularly in older patients. Chronic diseases further increase risk by contributing to inflammation and immobility.
- Obesity: While obesity is a risk factor at any age, its prevalence in older adults compounds the risk. Excess weight puts additional pressure on the veins in the legs, impeding healthy blood flow and increasing the risk of DVT.
Comparison of PE risk factors: Younger vs. Older adults
While PE is less common in younger individuals, the underlying causes often differ from those in the elderly population. The presence of multiple, compounding risk factors is more characteristic of older adults.
| Feature | Younger Adults (<40) | Older Adults (>60) |
|---|---|---|
| Incidence | Relatively rare (1 in 10,000 person-years) | Significantly higher (6-8 per 1000 person-years) |
| Typical Presentation | Often provoked by specific, identifiable triggers | Frequently unprovoked or linked to multiple comorbidities |
| Common Risk Factors | Oral contraceptives, pregnancy, hereditary thrombophilia, long-distance travel, recent trauma | Immobility, recent hospitalization or surgery, active cancer, chronic heart/lung disease |
| Physiological Basis | Often linked to specific genetic predispositions or temporary situations | Involves age-related hypercoagulable state and endothelial dysfunction |
| Symptom Presentation | May be more pronounced; tend to have fewer comorbidities to obscure diagnosis | Often atypical and nonspecific, making diagnosis more challenging |
| Severity | The same size PE may be less severe due to better cardiac reserve | Often more severe due to pre-existing heart or lung conditions |
Strategies for preventing VTE in older adults
Prevention is critical for older adults, given the higher risk and potential for severe outcomes. Proactive measures, especially in high-risk scenarios like hospitalization, are essential.
Common preventative measures include:
- Early and Frequent Ambulation: Post-surgery or during hospitalization, moving around as soon as safely possible is crucial. For those with limited mobility, simple seated exercises like ankle pumps and leg extensions can promote blood flow.
- Hydration: Staying well-hydrated, especially during long periods of immobility like air or car travel, helps prevent blood from thickening.
- Compression Therapy: Compression stockings can help prevent blood from pooling in the legs. For very high-risk, immobile patients, intermittent pneumatic compression devices may be used in a hospital setting.
- Anticoagulant Medication: High-risk individuals, such as those undergoing major surgery or with a history of VTE, may be prescribed blood-thinning medication as a preventative measure. For older adults with a confirmed VTE, appropriate anticoagulant therapy is the cornerstone of treatment.
- Lifestyle Management: Addressing modifiable risk factors is important. This includes quitting smoking, managing weight, and treating underlying chronic diseases effectively.
Conclusion
Understanding how does age cause pulmonary embolism is not about a single factor but a combination of complex physiological changes and an accumulation of risk factors common in later life. The age-related shift toward a pro-clotting state, coupled with increased rates of immobility, hospitalization, cancer, and chronic diseases, creates a perfect storm for VTE. While the risk is real, it's also manageable. By recognizing the heightened risk and implementing preventative measures, from simple exercises to medically prescribed anticoagulation, older adults can significantly reduce their risk of this potentially life-threatening condition. Given the often-atypical symptom presentation in the elderly, heightened clinical suspicion from both patients and healthcare providers is paramount for prompt diagnosis and treatment.
For more information on the management and treatment of VTE, consult the National Heart, Lung, and Blood Institute (NHLBI) at the National Institutes of Health.(https://www.nhlbi.nih.gov/health/venous-thromboembolism/treatment)
