Age is not just a number: older patients with lower extremity fractures have higher rates of pulmonary embolism despite anticoagulation

Background: Deep vein thrombosis occurs in 10%–20% of patients after orthopedic trauma, whereas the risk of pulmonary embolism (PE), which can have far more catastrophic consequences, is ~1%. There is also a difference in the physiologic response to trauma in younger patients compared with those who are more frail. The primary hypothesis was that increasing age is associated with increased PE risk. Methods: We conducted a retrospective cohort study using a national administrative claims database including adult patients with closed lower extremity fractures between 2011 and 2021, including pelvic, acetabular, femur, tibia, fibula, ankle, and calcaneus fractures. Patients with cancer or pre-injury anticoagulation were excluded. The primary outcome was PE incidence within 6 weeks after injury. Multivariable logistic regression models were used to evaluate the association between age and PE incidence adjusted for patient demographics, comorbidities, and post-injury anticoagulation. Results: In 6,514,870 patients (12% treated surgically), PE incidence was 0.3% in the nonoperative cohort and 0.6% in the surgically-treated cohort. In both cohorts, there was a progressive, age-dependent increase in PE incidence within 6 weeks after injury despite anticoagulation use. In the multivariable model, compared with patients younger than 50 years, patients older than or equal to 70 years had the highest adjusted odds for PE (nonoperative: OR=1.72, P <0.001). Conclusions: Older patients with closed lower extremity fractures have an increased PE risk even after accounting for anticoagulation and comorbidities, suggesting a need to revisit prophylaxis strategies and for increased vigilance in these at-risk patients.