Chemoprophylaxis for venous thromboembolism prevention in spine surgery patients
I read with interest the study by Sharpe et al.,1 and I would like to compliment the authors for their study. It shows that preoperative thromboprophylaxis with low-molecular weight heparin (LMWH) decreases the risk of pulmonary embolism without increasing bleeding complications in spine fracture patients receiving operative stabilization. Prevention criteria for patients with spinal surgery against venous thromboembolism (VTE) have not yet been unified. In a clinical setting, VTE is considered as a relatively rare complication in spinal surgery, LMWH is a common chemoprophylaxis for VTE prevention. However, the incidence of VTE has been reported to range from 0.8% to 22.4% with only LMWH applied. These varied evidences make clinicians hesitant to choose preventive measures for patients undergoing spinal surgery. The authors also mentioned that intermittent pneumatic compression has been used in the majority of the study population. When both mechanical and chemical prophylaxes were adapted, the incidence of DVT was reported to be as low as 0.2% to 0.7%, suggestive of combined thromboprophylaxis in spine surgery patients. The authors should specify that the conclusion about the benefit of preoperative LMWH was made in the context of mechanical prophylaxis. Our previous study indicated that asymptomatic cases accounted for a large proportion of VTE patients. Silent VTE could have been missed because examinations were only performed in symptomatic patients.2 Besides, the authors did not check and exclude preoperative VTE. Potential benefit of preoperative chemoprophylaxis could also be mediated by the prevention of preoperative VTE cases.
In clinical practice, benefit of chemoprophylaxis and risk of potential epidural hematoma (EH) were constantly brought up in VTE prevention. Though a preoperative chemoprophylaxis strategy was applied, however, no EH was observed in the study by Sharpe et al. The incidence of symptomatic EH after spine surgery was reported to range from 0.1% to 3%. Other studies have also indicated that anticoagulation for spine surgery did not lead to the increase of symptomatic EH risk.3,4 To date, no positive association has been confirmed between anticoagulation and EH in any spine surgery study except case reports. Clinical trials about anticoagulation benefit and EH risk should be conducted to provide solid evidence for this debate.