Prevention and Treatment of Thromboembolism in the Elderly

Challenges of Thromboembolic Prophylaxis in the Elderly

The risk of venous thrombosis increases exponentially with age. Thromboprophylaxis in elderly patients is often suboptimal due to bleeding concerns – the risk factors for thromboembolism (VTE) frequently overlap with the bleeding risk profile in this group. An expert group of 44 leading specialists from various continents noted that the systems for VTE risk assessment and recommended thromboembolic prophylaxis guidelines vary significantly across countries.

Older patients are also underrepresented in clinical trials due to frequent comorbidities. As a result, some expert recommendations may be extrapolated from studies conducted in younger patients and may not necessarily meet the needs of the elderly population. Thromboprophylaxis should therefore be prescribed after careful assessment of the risks and benefits for each patient.

Assessing VTE Risk

Evaluating the individual VTE risk in elderly patients should include comorbidities (including renal function, hypertension, coronary artery disease, and infections), current medication, and frailty assessment. Bleeding risk should also be considered.

The use of biomarkers is still unclear. While D-dimer levels have been shown in clinical studies to be a good predictor of thromboembolism risk in acutely ill patients, they may not be effective predictors in the oldest individuals, who generally have higher circulating D-dimer levels. More studies are needed to determine reliable threshold values in this population.

Extended Prophylaxis

The expert group suggests that patients at high VTE risk (e.g., post-surgery or with active cancer) should receive extended prophylaxis for 35 days. The EXCLAIM clinical study showed a reduction in VTE incidence in acutely ill patients over 75 years old who received low-molecular-weight heparins (LMWH) for up to 38 days post-hospitalization. However, this benefit was offset by an increased frequency of bleeding events, and the administration of extended prophylaxis should be considered individually for each patient.

Treatment of Thromboembolism and Secondary Prevention

Anticoagulant therapy with LMWH is the standard approach in hospitalized elderly patients with comorbidities such as chronic inflammatory conditions, gastrointestinal issues, impaired renal function, active cancer, acute or chronic heart and lung diseases, or acute infections.

Long-term LMWH treatment is uncommon, mainly due to user inconvenience and cost. Typically, long-term oral anticoagulants, either vitamin K antagonists or direct oral anticoagulants (DOACs), follow a short initial therapy with LMWH. The efficacy and safety of DOACs have been evaluated in numerous clinical studies, most of which had patients in the control arm using vitamin K antagonists. Direct comparisons of LMWH and DOACs in patients over 75 years old are not yet available, and there is a lack of robust real-world data.

Conclusion

In elderly patients, individual assessment of the benefits and risks of thromboembolic prophylaxis is essential. Regarding treatment and secondary prevention, further studies are needed to determine which anticoagulant regimen is most suitable for older outpatient populations.

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Sources:
1. Brenner B., Arya R., Beyer-Westendorf J. et al. Evaluation of unmet clinical needs in prophylaxis and treatment of venous thromboembolism in at-risk patient gps: pregnancy, elderly and obese patients. Thromb J 2019; 17: 24, doi: 10.1186/s12959-019-0214-8.
2. Yusen R. D., Hull R. D., Schellong S. M. et al. Impact of age on the efficacy and safety of extended-duration thromboprophylaxis in medical patients. Subgroup analysis from the EXCLAIM randomised trial. Thromb Haemost 2013; 110 (6): 1152−1163, doi: 10.1160/TH13-02-0170.