Study: Therapeutic Anticoagulation After Spine Surgery Linked with Complications

By: Terry Stanton

A study that sought to quantify complications secondary to therapeutic anticoagulation after spine surgery for trauma found a relatively high rate of complications requiring reoperation associated with such therapy, including a
3 percent incidence of spinal epidural hematoma, which compares to a historical epidural hematoma rate of 0.2 percent.

The authors of the study, presented Tuesday by Brian Shiu, MD, chief resident at the University of Maryland orthopaedics department, also found that anticoagulation using a heparin infusion compared with low molecular weight heparin (LMWH) may increase the rate of reoperation. Overall, the study detected a “relatively high” overall rate (17.5 percent) of complications requiring reoperation after surgeries involving anticoagulation agents.

Dr. Shiu said he and his colleagues were prompted to undertake the study in hopes of addressing a gap in literature regarding full-dose anticoagulation. “We present our cases in conference every month, and we come across patients who have had thromboembolic complications such as pulmonary embolism (PE) and deep vein thrombosis (DVT),” Dr. Shiu said. “When the time comes to treat these patients with full therapeutic anticoagulation, the main concern is the catastrophic epidural hematoma as well as bleeding complications. After examination of the literature, we found there has never been a study to document the incidence of complications after full anticoagulation. In other words, when we look at outcomes, we have no studies to guide us in terms of patient counseling and surgeon expectations.”

He said that this is the first study to establish the rate of complications after initiation of full anticoagulation. “As expected, the risk of complications severe enough to require an unplanned reoperation was significantly higher in these patients with a nearly 20 percent reoperation rate after initiation of anticoagulation,” he said. The most common complications were wound infections and bleeding complications with the 3 percent incidence of symptomatic epidural hematomas. “Surprisingly, we found an increased rate of bleeding complications when using a heparin infusion, although further studies are needed to clarify this association,” Dr. Shiu said.

The clinical takeaway from the study is, Dr. Shiu said, “When a patient sustains a DVT, PE, or myocardial infarction that requires full therapeutic anticoagulation, complications will be frequent, with the vast majority occurring within postoperative day 26. This is the first study to establish the incidence of complications to guide us in terms of patient counseling and surgeon expectations.”

Limitations included the fact that it is a retrospective study with inherent biases. The authors stated, “We also could not evaluate in real time the level of anticoagulation with heparin infusion to see if complications noted were associated with patients being supra-therapeutic. However, we are currently looking deeper into factors predisposing to complications secondary to therapeutic anticoagulation.”

The abstract for the study, scheduled to be presented at 4:54 p.m. in room W315, reads as follows:

Hypothesis: We hypothesize a high complication rate following therapeutic anticoagulation in the postoperative spine trauma patient.

Design: Retrospective clinical study

Introduction: There have been numerous studies on prophylactic anticoagulation after spinal surgery, but none have investigated the risks of therapeutic anticoagulation for the treatment of a thromboembolic event. The incidence of complications secondary to initiation of therapeutic anticoagulation, including clinically significant spinal epidural hematoma, has not been established.

Methods: A retrospective review was conducted using prospectively collected data at a level-1 trauma center. Patient selection criteria included those who: (1) underwent spinal surgery and (2) sustained a thromboembolic event (pulmonary embolism, deep vein thrombosis or myocardial infarction). Patients were excluded if (1) the thromboembolic event was sustained before spinal surgery, (2) anticoagulation was sub-therapeutic (PTT <60, INR <2, or 3) medical records were not available. Of 1,712 patients, 63 patients met these criteria (2001–2014). 

Results: Initial anticoagulation was obtained by a heparin infusion, LMWH, and warfarin in 32 (50.7%), 29 (46.0%), and 2 (3.2%) patients, respectively. IVC filters were placed in 16 (25.4%) patients. After postoperative initiation of therapeutic anticoagulation, 11 (17.5%) patients sustained complications requiring return to the operating room with 10 of 11 patients returning within the first 26 days. Two (3%) patients underwent reexploration due to the development of epidural hematomas causing neurologic decline; both patients were initially anticoagulated by heparin infusion. The remaining patients in our cohort required reoperation due to other causes such as wound infection, hemorrhage from tracheostomy site, and pseudarthrosis. Our multivariate model demonstrated a 13.3 times higher odds (P = 0.039) for reoperation due to a spinal surgery complication and a 17.9 times higher odds (P = 0.048) for reoperation for any reason with the initial use of a heparin infusion compared with LMWH. Thromboembolic complications and subsequent anticoagulation occurred at an average of 10.3 and 12.5 days after surgery, respectively.

Conclusion: To our knowledge, this represents the first attempt to quantify complications secondary to therapeutic doses of anticoagulation after spine surgery. We found a relatively high rate (17.5%) of complications requiring reoperation, including a 3 percent incidence of spinal epidural hematoma compared to a historical epidural hematoma rate of 0.2 percent. Furthermore, initial anticoagulation using a heparin infusion compared with LMWH may increase the rate of reoperation.   

Coauthors with Dr. Shiu of  “Incidence of Complications After Therapeutic Anticoagulation in the Spine Trauma Patient” are Elizabeth Le, MD; Ehsan Jazini, MD; Timothy Costales; Nicholas Caffes, BS; Ebrahim Paryavi, MD, MPH; Eugene Y. Koh, MD; Daniel E. Gelb, MD; and Steven C. Ludwig, MD.

Details of the authors’ disclosures as submitted to the Orthopaedic Disclosure Program can be found in the Final Program; the most current disclosure information may be accessed electronically at www.aaos.org/disclosure

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