High Rate of Fatal Pulmonary Embolism Noted In Patients Undergoing Spine Surgery for Metastases
Key findings
- Of 637 patients who underwent surgery for spine metastatic bone lesions, 11% developed symptomatic venous thromboembolism (VTE), including 6% who developed symptomatic pulmonary embolism (PE)
- 1.3% of all patients in this series died of PE
- Longer duration of surgery was independently associated with an increased risk of VTE
- The one-year survival rate was significantly worse for patients who developed VTE than those who did not
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Both cancer and spine surgery are independent risk factors for symptomatic venous thromboembolism (VTE), so patients having surgery for spine metastases are at particular risk. In one recent study, 22% of patients undergoing surgery for tumors developed VTE.
VTE in cancer patients has been linked to poor survival. Still, surgeons may hesitate to use chemical anticoagulants after spine surgery because of the risk of severe hemorrhagic complications, including spinal epidural hematoma.
In a retrospective study, Joseph H. Schwab MD, chief of the Orthopaedic Spine Center at Massachusetts General Hospital, and colleagues detected an 11% incidence of VTE in this population—most worrisomely an unprecedently high rate of fatal pulmonary embolism. The study appears in Clinical Orthopaedics and Related Research.
The study, conducted at Mass General and Brigham and Women's Hospital, included 637 adults who had surgery for cervical, thoracic or lumbar metastatic bone lesions (including from lymphoma or multiple myeloma) between January 2002 and January 2014.
During the study period, the authors used either 40 mg of enoxaparin or 5000 IU subcutaneous heparin every 12 hours as thromboembolic prophylaxis. Other approaches were 325 mg aspirin daily, 5000 IU dalteparin daily or warfarin to maintain an international normalized ratio of 2.0/2.5.
All chemical chemoprophylaxis was started 48 hours after surgery and continued for up to 14 days unless a bleeding complication developed. When chemoprophylaxis was contraindicated, an inferior vena cava filter was placed before surgery. Mechanical prophylaxis (sequential compression devices and compression stockings) was used for all patients.
Primary Outcome
Symptomatic VTE was diagnosed within 90 days after surgery in 72 patients (11%). This included 34 patients with deep vein thrombosis (DVT), 32 with pulmonary embolism (PE) and six patients with both. Eight PEs were fatal (1.3% of the entire cohort), a higher rate than in any other known study.
The rate of VTE increased after postoperative day 30 and kept rising. Indeed, half of the cases occurred more than three weeks after surgery, considerably longer compared with the average length of hospital stay (eight days for DVT and PE, 14 days for fatal PE). The occurrence of fatal PE ranged from postoperative day 1 to day 78.
After adjustment for age, sex and other potential confounding variables, the only risk factor for VTE was a longer duration of surgery (OR, 1.15 for each additional hour of surgery; 95% CI, 1.04–1.28; P = .009). Use of chemoprophylaxis had no effect.
Secondary Outcomes
The one-year survival rate was significantly lower for patients who developed VTE than those who did not (38% vs. 47%; P = .04). This observation may reflect overall infirmity as much as anything else because many patients did not die from complications related to VTE. On the other hand, the high incidence of fatal PE suggests that VTE prevention might improve short-term survival.
Twelve deep wound complications occurred: seven symptomatic spinal epidural hematomas, four seromas and one splenic bleed on postoperative day nine.
There was no association between the occurrence of wound complications and any of the different chemoprophylaxis regimens. Likewise, there was no difference in wound complications between patients who did or did not receive an anticoagulant, but that analysis was underpowered.
Guidance for Surgeons
- Prolonged surgical procedures may warrant greater consideration of chemoprophylaxis against VTE
- Considering the potential late onset of VTE, longer duration of anticoagulant use may be indicated
- Because there is a trend toward shorter hospitalizations after major orthopedic surgery, surgeons should monitor patients' compliance with outpatient anticoagulant prophylaxis
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