SLR - December 2015 - Robert Rawski
Title: A Double-Blind, Randomized Controlled Trial of the Prevention of Clinically Important Venous Thromboembolism After Isolated Lower Leg Fractures
Reference: Selby R, Geerts WH, Kreder HJ, Crowther MA, Kaus L, Sealey F; D-KAF (Dalteparin in Knee-to- Ankle Fracture) Investigators. A Double-Blind, Randomized Controlled Trial of the Prevention of Clinically Important Venous Thromboembolism After Isolated Lower Leg Fractures. J Orthop Trauma. 2015 May; 29(5):224-230.
Scientific Literature Review
Reviewed By: Robert Rawski, DPM
Residency Program: Columbia St. Mary’s Hospital, Milwaukee, WI
Podiatric Relevance: Lower extremity fractures are commonly seen by a practicing foot and ankle surgeon. These types of injuries are known to be risk factors for venous thromboembolisms. Even with this knowledge, there is uncertainty about the need for thromboprophylaxis resulting in significant practice variation in podiatry, as well as other fields. The main objective of this article was to assess the effectiveness and safety of LMWH compared with placebo for the prevention of clinically important venous thromboembolism (CIVTE) in patients with isolated fractures distal to the knee that were managed surgically.
Methods: This was a multicenter, double-blind trial that included 265 patients with isolated lower leg fractures requiring surgery that were randomized to subcutaneous dalteparin 5000 units or matching placebo once daily for two weeks with bilateral Doppler ultrasound of the proximal leg veins on postoperative day 14±2 and 3-month follow-up. The primary effectiveness outcome was clinically important venous thromboembolism (CIVTE), defined as the composite of symptomatic venous thromboembolism within three months after surgery and asymptomatic proximal deep vein thrombosis on Doppler ultrasound. The primary safety outcome was major bleeding.
Results: Two hundred fifty-eight patients (97 percent) were included in the primary outcome analysis for effectiveness (130: dalteparin; 128:placebo). Incidence of CIVTE in the dalteparin and placebo groups was 1.5 percent and 2.3 percent, respectively (absolute risk reduction, 0.8 percent; 95 percent confidence interval, 22.0 to 3.0). There were no fatal pulmonary emboli or major bleeding.
Conclusions: The authors concluded that the overall incidence of CIVTE after surgically repaired, isolated tibia, fibula, and ankle fractures was low (1.9 percent; 95 percent confidence interval, 0.7–4.7), with no observed differences between dalteparin and placebo either for CIVTE or safety. This study also demonstrates the substantial discrepancy in venous thromboembolism rates between trials that use venographic outcomes compared with more clinically relevant outcomes. This article makes me question the idea of thromboprophylaxis for lower extremity fractures requiring surgical intervention, especially if there is no difference between LMWH and placebo. However, it comes down to standard of care, which does guide the direction of medical treatment to an extent.