Incidence and Risk Factors Associated With Venous Thromboembolism After Orthopaedic Below-Knee Surgery

Reinout R.O. Heijboer, MD; Bart Lubberts, MD; Daniel Guss, MD, MBA; A. Holly Johnson, MD; Christopher W. DiGiovanni, MD

Disclosures

J Am Acad Orthop Surg. 2019;27(10):e482-e490. 

In This Article

Results

In this study, 10,023 women (50%) were with a median age of 53 years (IQR, 39 to 63 SD) and 10,020 men (50%) were with a median age of 48 years (IQR, 34 to 60). Of these patients, 5,610 patients (28%) underwent forefoot/midfoot surgery, 2,286 patients (11%) underwent hindfoot/ankle surgery, 5,322 patients (27%) underwent lower leg surgery, and 6,825 patients (34%) underwent some combination of forefoot/midfoot, hindfoot/ankle, and/or lower leg surgery during a single intervention (Table 1 and see Supplement 1, Supplemental Digital Content 4, http://links.lww.com/JAAOS/A197).

A symptomatic DVT developed in two hundred ninety-five patients (1.5%), a PE in 124 patients (0.6%), and both DVT and PE in 73 patients (0.4%), resulting in an overall incidence of symptomatic thromboembolic event of 2.5% (n = 492). Symptomatic DVT occurred at a median of 17 days (IQR, 5 to 44 days) after surgery, whereas symptomatic PE occurred at a median of 8 days (IQR, 2 to 39 days) after surgery. Twenty-nine patients (5.9%; 29/492) diagnosed with VTE died within 90 days after surgery, whereas 285 patients (1.5%; 285/19,551) without VTE died within 90 days after surgery. The associated relative risk of mortality after developing a VTE event was 3.9 (95% CI, 3.5 to 6.7; P < 0.001) (Table 2).

Factors associated with developing VTE regardless of thromboprophylaxis use were male sex (OR, 1.8; 95% CI, 1.4 to 2.2; P < 0.001), age 65 years or older (OR, 1.4; 95% CI, 1.1 to 1.9; P = 0.013), lower leg surgery (OR, 3.3; 95% CI, 2.5 to 4.3; P < 0.001), combination surgery (OR, 2.1; 95% CI, 1.6 to 2.9; P < 0.001), anticoagulant use (OR, 1.4; 95% CI, 1.1 to 1.8; P = 0.002), history of VTE (OR, 5.3; 95% CI, 4.0 to 6.7; P < 0.001), family history of cardiovascular disease (OR, 1.7; 95% CI, 1.1 to 2.6; P = 0.024), and Charlson Comorbidity Index greater than 2 (OR, 1.3; 95% CI, 1.0 to 1.7; P = 0.023) (Table 1 and Supplement 1, Supplemental Digital Content 4, http://links.lww.com/JAAOS/A197). The risk for developing VTE in these populations was not found to be lowered by thromboprophylaxis and in fact was markedly increased in certain subgroups receiving thromboprophylaxis (Table 3).

Compared with patients who had not received thromboprophylaxis, patients who had been treated with an anticoagulant agent were more frequently male (OR, 1.6; 95% CI, 1.5 to 1.7; P < 0.001), older than 65 years (OR, 1.8; 95% CI, 1.7 to 2.0; P < 0.001), had a BMI greater than 40 (OR, 1.4; 95% CI, 1.2 to 1.6; P < 0.001), nonwhite (OR, 1.3; 95% CI, 1.2 to 1.4; P < 0.001), underwent lower leg surgery (OR, 3.5; 95% CI, 3.2 to 3.7; P < 0.001), underwent combination surgery (OR, 1.8; 95% CI, 1.7 to 1.9; P < 0.001), were former smokers (OR, 1.5; 95% CI, 1.4 to 1.6; P < 0.001) or current smokers (OR, 2.2; 95% CI, 2.0 to 2.4; P < 0.001), were pregnant (OR, 2.0; 95% CI, 1.1 to 3.5; P = 0.023), had a history of VTE (OR, 2.9; 95% CI, 2.5 to 3.3; P < 0.001), had known hypercoagulability (OR, 4.1; 95% CI, 2.6 to 6.6; P < 0.001), or a Charlson Comorbidity Index greater than 2 (OR, 2.6; 95% CI, 2.4 to 2.9; P < 0.001) (see Supplement 2, Supplemental Digital Content 5, http://links.lww.com/JAAOS/A198).

No Pharmacologic Thromboprophylaxis

The incidence rate of a thromboembolic event in patients who did not receive pharmacologic thromboprophylaxis was 1.5% (134/9,127 patients). A thromboembolic event occurred at a median of 25.3 days (IQR, 4 to 43) postoperatively. Male sex (OR, 1.6; 95% CI, 1.1 to 2.2; P = 0.015), nonwhite race (OR, 1.6; 95% CI, 1.0 to 2.4; P = 0.041), lower leg surgery (OR 3.3; 95% CI, 2.0 to 5.3; P < 0.001), combination surgery (OR, 2.4; 95% CI, 1.5 to 3.9; P < 0.001), history of VTE (OR, 7.2; 95% CI, 4.3 to 12; P < 0.001), and a Charlson Comorbidity Index greater than 2 (OR, 1.8; 95% CI, 1.1 to 2.9; P = 0.023) were factors associated with increased risk for VTE in patients who had not received thromboprophylaxis (Table 4 and Supplement 3, Supplemental Digital Content 6, http://links.lww.com/JAAOS/A199).

Antiplatelet Agent

In patients who received an antiplatelet agent, the incidence rate of a thromboembolic event was 1.7% (33/1,992 patients). A thromboembolic event developed within a median of 28 days (IQR, 7.5 to 37) after surgery.

Anticoagulant Agent

In patients who received an anticoagulant agent, the incidence of thromboembolic event was 3.6% (325/8,924 patients). A thromboembolic event occurred within a median of 23 days (IQR, 4 to 36) postoperatively. Risk factors associated with VTE in patients who had been treated with an anticoagulant agent were male sex (OR, 1.8; 95% CI, 1.4 to 2.3; P < 0.001), lower leg surgery (OR, 2.9; 95% CI, 2.0 to 4.3; P < 0.001), combination surgery (OR, 1.7; 95% CI, 1.1 to 2.6; P = 0.009), and individuals with a history of VTE (OR, 3.8; 95% CI, 2.8 to 5.2; P < 0.001) (Table 5 and Supplement 4, Supplemental Digital Content 7, http://links.lww.com/JAAOS/A200).

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