Venous Thromboembolism Prophylaxis in Elective Spine Surgery

Machine learning approach to predict venous thromboembolism among patients undergoing multi-level spinal posterior instrumented fusion

Background

The absence of consensus for prophylaxis of venous thromboembolism (VTE) in spine surgery underscores the importance of identifying patients at risk. This study incorporated machine learning (ML) models to assess key risk factors of VTE in patients who underwent posterior spinal instrumented fusion.

Methods

Data was collected from the IBM MarketScan Database [2009-2021] for patients ≥18 years old who underwent spinal posterior instrumentation (3-6 levels), excluding traumas, malignancies, and infections. VTE incidence (deep vein thrombosis and pulmonary embolism) was recorded 90-day post-surgery. Risk factors for VTE were investigated and compared through several ML models including logistic regression, linear support vector machine (LSVM), random forest, XGBoost, and neural networks.

Results

Among the 141,697 patients who underwent spinal fusion with posterior instrumentation (3-6 levels), the overall 90-day VTE rate was 3.81%. The LSVM model demonstrated the best prediction with an area under the curve (AUC) of 0.68. The most important features for prediction of VTE included remote history of VTE, diagnosis of chronic hypercoagulability, metastatic cancer, hemiplegia, and chronic renal disease. Patients who did not have these five key risk factors had a 90-day VTE rate of 2.95%. Patients who had an increasing number of key risk factors had subsequently higher risks of postoperative VTE.

Conclusions

The analysis of the data with different ML models identified 5 key variables that are most closely associated with VTE. Using these variables, we have developed a simple risk model with additive odds ratio ranging from 2.80 (1 risk factor) to 46.92 (4 risk factors) over 90 days after posterior spinal fusion surgery. These findings can help surgeons risk-stratify their patients for VTE risk, and potentially guide subsequent chemoprophylaxis.

Cervical Spine Surgery Following COVID-19 Infection: When is it Safe to Proceed?

STUDY DESIGN

Retrospective.

OBJECTIVE

We utilized the NIH National COVID Cohort Collaborative (N3C) database to characterize the risk profile of patients undergoing spine surgery during multiple time windows following the COVID-19 infection.

SUMMARY OF BACKGROUND DATA

While the impact of COVID-19 on various organ systems is well documented, there is limited knowledge regarding its effect on perioperative complications following spine surgery or the optimal timing of surgery after an infection.

METHODS

We asked the National COVID Cohort Collaborative for patients who underwent cervical spine surgery. Patients were stratified into those with an initial documented COVID-19 infection within 3 time periods: 0-2 weeks, 2-6 weeks, or 6-12 weeks before surgery.

RESULTS

A total of 29,449 patients who underwent anterior approach cervical spine surgery and 46,379 patients who underwent posterior approach cervical spine surgery were included. Patients who underwent surgery within 2 weeks of their COVID-19 diagnosis had a significantly increased risk for venous thromboembolic events, sepsis, 30-day mortality, and 1-year mortality, irrespective of the anterior or posterior approach. Among patients undergoing surgery between 2 and 6 weeks after COVID-19 infection, the 30-day mortality risk remained elevated in patients undergoing a posterior approach only. Patients undergoing surgery between 6 and 12 weeks from the date of the COVID-19 infection did not show significantly elevated rates of any complications analyzed.

CONCLUSIONS

Patients undergoing either anterior or posterior cervical spine surgery within 2 weeks from the initial COVID-19 diagnosis are at increased risk for perioperative venous thromboembolic events, sepsis, and mortality. Elevated perioperative complication risk does not persist beyond 2 weeks, except for 30-day mortality in posterior approach surgeries. On the basis of these results, it may be warranted to postpone nonurgent spine surgeries for at least 2 weeks following a COVID-19 infection and advise patients of the increased perioperative complication risk when urgent surgery is required.

Chemoprophylactic Anticoagulation After Spine Surgery Does Not Increase Epidural Hematoma Risk: A Propensity-matched Analysis

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To calculate the magnitude of any increased risk of epidural hematoma (EDH) associated with chemoprophylactic anticoagulation (chemoprophylaxis), if any.

SUMMARY OF BACKGROUND DATA

Chemoprophylaxis for the prevention of venous thromboembolic events may be associated with an increased risk of EDH after spine surgery.

MATERIALS AND METHODS

A total of 6869 consecutive spine surgeries performed at our institution were identified, and clinical and demographic data were collected. We identified cases in which symptomatic EDHs were evacuated within 30 days postoperatively. Patients receiving chemoprophylaxis and controls were matched using K-nearest neighbor propensity score matching to calculate the effect of anticoagulation on the rate of postoperative EDH.

RESULTS

After propensity score matching, 1071 patients who received chemoprophylaxis were matched to 1585 controls. Propensity scores were well balanced between populations (Rubin B=20.6, Rubin R=1.05), and an 89.6% reduction in bias was achieved, with a remaining mean bias of 3.2%. The effect of chemoprophylaxis on EDH was insignificant ( P =0.294). Symptomatic EDH was independently associated with having a transfusion [odds ratio (OR)=7.30 (1.15, 46.20), P =0.035], having thoracic-level surgery [OR=41.19 (3.75, 452.4), P =0.002], and increasing body mass index [OR=1.44 (1.04, 1.98), P =0.028] but was not associated with chemoprophylaxis. Five out of 13 patients who developed EDH (38.5%) were receiving some form of anticoagulation, including 1 patient on therapeutic anticoagulation, 1 concurrently on aspirin and chemoprophylaxis, and 2 who were also found to have developed thrombocytopenia postoperatively. The median time on anticoagulation before EDH was 8.1 days. A higher proportion of patients who developed EDH also developed venous thromboembolic events than the general population [38.5% vs. 2.4%, OR=25.34 (9.226, 79.68), P <0.0001], and 1 EDH patient died from pulmonary embolism while off chemoprophylaxis.

CONCLUSIONS

Chemoprophylactic anticoagulation did not cause an increase in the rate of spinal EDH in our patient population.

The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) levels following erector spinae plane block (ESPB) in posterior lumbar decompression: a randomized, controlled trial

PURPOSE

Neutrophile-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are the inflammatory biomarkers of the stress response. In this study, we aimed to evaluate the effects of erector spinae plane block (ESPB) on posterior lumbar decompression and stabilization by comparing NLR, PLR, postoperative pain, opioid consumption, and functional recovery between sham block and ESPB.

METHODS

This was a prospective, double-blinded, randomized controlled trial in a tertiary referral hospital. Sixty patients were randomized into two equal groups, each receiving either a sham block or ESPB. The primary outcome was the NLR and PLR 12 h and 24 h after lumbar posterior decompression and stabilization. The secondary outcomes were total opioid consumption and pain score 24 h postoperatively. Also, functional recovery determined by getting out of bed, verticalization, and walking by the balcony were reviewed as secondary outcomes.

RESULTS

Significant differences existed between the sham block and ESPB group in NLR (29.08 ± 12.29 vs. 16.97 ± 10.38; p < 0.0001) and PLR (556.77 ± 110.32 vs. 346.43 ± 117.34; p < 0.0001) 12 h after surgery. Also, there was a significant difference in NLR (p = 0.0466) and PLR (p < 0.0001) 24 h after surgery. In addition, there was a substantial difference in pain score, total opioid consumption, and functional recovery.

CONCLUSION

ESPB performance during spinal surgery lowers NRL and PLR ratios 12 h and 24 h after surgery. In addition, ESPB provides better analgesia and improves functional recovery compared to sham block following posterior lumbar decompression and stabilization.

Thromboembolic prophylaxis in spine surgery: an analysis of ChatGPT recommendations

BACKGROUND CONTEXT

Venous thromboembolism is a negative outcome of elective spine surgery. However, the use of thromboembolic chemoprophylaxis in this patient population is controversial due to the possible increased risk of epidural hematoma. ChatGPT is an artificial intelligence model which may be able to generate recommendations for thromboembolic prophylaxis in spine surgery.

PURPOSE

To evaluate the accuracy of ChatGPT recommendations for thromboembolic prophylaxis in spine surgery.

STUDY DESIGN/SETTING

Comparative analysis.

PATIENT SAMPLE

None.

OUTCOME MEASURES

Accuracy, over-conclusiveness, supplemental, and incompleteness of ChatGPT responses compared to the North American Spine Society (NASS) clinical guidelines.

METHODS

ChatGPT was prompted with questions from the 2009 NASS clinical guidelines for antithrombotic therapies and evaluated for concordance with the clinical guidelines. ChatGPT-3.5 responses were obtained on March 5, 2023, and ChatGPT-4.0 responses were obtained on April 7, 2023. A ChatGPT response was classified as accurate if it did not contradict the clinical guideline. Three additional categories were created to further evaluate the ChatGPT responses in comparison to the NASS guidelines: over-conclusiveness, supplementary, and incompleteness. ChatGPT was classified as over-conclusive if it made a recommendation where the NASS guideline did not provide one. ChatGPT was classified as supplementary if it included additional relevant information not specified by the NASS guideline. ChatGPT was classified as incomplete if it failed to provide relevant information included in the NASS guideline.

RESULTS

Twelve clinical guidelines were evaluated in total. Compared to the NASS clinical guidelines, ChatGPT-3.5 was accurate in 4 (33%) of its responses while ChatGPT-4.0 was accurate in 11 (92%) responses. ChatGPT-3.5 was over-conclusive in 6 (50%) of its responses while ChatGPT-4.0 was over-conclusive in 1 (8%) response. ChatGPT-3.5 provided supplemental information in 8 (67%) of its responses, and ChatGPT-4.0 provided supplemental information in 11 (92%) responses. Four (33%) responses from ChatGPT-3.5 were incomplete, and 4 (33%) responses from ChatGPT-4.0 were incomplete.

CONCLUSIONS

ChatGPT was able to provide recommendations for thromboembolic prophylaxis with reasonable accuracy. ChatGPT-3.5 tended to cite nonexistent sources and was more likely to give specific recommendations while ChatGPT-4.0 was more conservative in its answers. As ChatGPT is continuously updated, further validation is needed before it can be used as a guideline for clinical practice.

Severe Symptomatic Epidural Hematoma Following Percutaneous Endoscopic Unilateral Laminectomy for Bilateral Decompression (Endo-ULBD)-Series Report and Management Strategies

OBJECTIVES

Severe symptomatic epidural hematoma (SSEH) is one of the most severe complications following percutaneous endoscopic unilateral laminectomy for bilateral decompression (Endo-ULBD). Considering that this technique has been performed for a short time, no detailed reports have been recently published. Thus, it is critical to gain a better understanding of SSEH occurring in its postoperative period with regard to its incidence, possible causes, outcome, etc., in order to identify relevant management strategies.

METHODS

Patients with spinal stenosis who had undergone Endo-ULBD in our department from May 2019 to May 2022 were retrospectively analyzed. Of which, patients with postoperative epidural hematoma were followed-up. The preoperative and postoperative physical conditions of each patient were recorded, and the information related to hematoma removal surgery was recorded in detail. Clinical outcomes were assessed using the visual analogue scale (VAS) and Oswestry disability index (ODI), and the results were classified into "excellent," "good," "fair," or "poor" based on the modified MacNab criteria. The incidence of hematoma with different factors was calculated, and a bar graph was used to compare the difference of the indexes related to hematoma removal between cases, and a line graph was used to reflect the trend of the outcome of each patient within 6 months to evaluate the effect of the treatment.

RESULTS

A total of 461 patients with spinal stenosis who underwent Endo-ULBD were enrolled in the study. SSEH occurred in four cases, with an incidence rate of 0.87% (4/461). All these four patients underwent decompression of multiple segments, and three of them had a history of hypertension comorbid with diabetes. Notably, one patient had a past history of hypertension and coronary artery disease and was on postoperative low molecular heparin due to lower extremity venous thrombosis. According to the conditions of the four patients, three types of treatment were used. And with timely treatment, all patients recovered well.

CONCLUSION

Despite being a minimally invasive technique, postoperative epidural hematoma remains a severe complication of Endo-ULBD. Therefore, during percutaneous endoscopic surgery, it is essential to enhance the comprehensive perioperative management of patients with Endo-ULBD. Signs related to postoperative hematoma must be recognized and promptly managed. If necessary, satisfactory results can be achieved by using percutaneous endoscopy along the original surgical channel to remove the hematoma.

Is it safe for the spinal metastasis patients with preoperative deep vein thrombosis to use low-molecular-weight heparin before surgery? A prospective study

Spine surgeons should weigh the risks of anticoagulants against their benefits in preventing deep venous thrombosis (DVT), as they may increase the risk of bleeding. Spinal metastasis patients undergoing decompression with fixation are at a high risk for DVT, which may occur preoperatively. Therefore, anticoagulants should be administered preoperatively. This study aimed to evaluate the safety of the administration of anticoagulants in treating spinal metastasis patients with preoperative DVT. Therefore, we prospectively investigated the prevalence of DVT in these patients. Patients who were diagnosed with preoperative DVT were included in an anticoagulant group. Subcutaneous low-molecular-weight heparin (LMWH) was administered. Patients without DVT were included in a non-anticoagulant group. Data on patient information, clinical parameters, blood test results, and bleeding complications were also collected. Moreover, the safety of anticoagulants was analyzed. The prevalence of preoperative DVT was 8.0%. None of the patients developed pulmonary thromboembolism. Furthermore, no significant differences in blood loss, drainage volume, hemoglobin levels, number of transfusions, or preoperative trans-catheter arterial embolization were observed between the two groups. None of the patients developed major bleeding. However, two patients experienced wound hematoma and one experienced incisional bleeding in the non-anticoagulant group. Therefore, LMWH is safe for spinal metastasis patients. Future randomized controlled trials should be conducted to evaluate the validity of perioperative prophylactic anticoagulation therapy in these patients.

Venous Thromboembolism Rates Have Not Decreased in Elective Lumbar Fusion Surgery from 2011 to 2020

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to (1) evaluate for any temporal trends in the rates of VTE, deep venous thrombosis (DVT), pulmonary embolism (PE), and mortality from 2011 to 2020 and (2) identify the predictors of VTE following lumbar fusion surgery.

METHODS

Annual incidences of 30-day VTE, DVT, PE, and mortality were calculated for each of the operation year groups from 2011 to 2020. Multivariable Poisson regression was utilized to test the association between operation year and primary outcomes, as well as to identify significant predictors of VTE.

RESULTS

A total of 121,205 patients were included. There were no statistically significant differences in VTE, DVT, PE, or mortality rates among the operation year groups. Multivariable regression analysis revealed that compared to 2011, operation year 2019 was associated with significantly lower rates of DVT. Age, BMI, prolonged operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking status, functional dependence, and chronic steroid use were identified as independent predictors of VTE following lumbar fusion. Female sex, Hispanic ethnicity, and outpatient surgery setting were identified as protective factors from VTE in this cohort.

CONCLUSIONS

Rates of VTE after lumbar fusion have remained mostly unchanged between 2011 and 2020. Older age, higher BMI, longer operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking, functional dependence, and steroid use were independent predictors of VTE after lumbar fusion, while female sex, Hispanic ethnicity, and outpatient surgery were the protective factors.

Chemoprophylactic Anticoagulation Following Lumbar Surgery Significantly Reduces Thromboembolic Events After Instrumented Fusions, Not Decompressions

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To quantify any reduction in venous thromboembolic events (VTEs) caused by chemoprophylaxis among lumbar surgery patients.

SUMMARY OF BACKGROUND DATA

Chemoprophylactic anticoagulation (chemoprophylaxis) is used to prevent VTE after lumbar surgery. However, the treatment effect of chemoprophylaxis has not been reported among spine surgery patients, as conventional statistical methods preclude such inferences.

MATERIALS AND METHODS

A total of 1243 consecutive lumbar fusions and 1433 noninstrumented lumbar decompressions performed at our institution over a six-year period were identified, and clinical and demographic data were collected, including on VTE events within 30 days postoperatively. Instrumented lumbar fusions and noninstrumented lumbar surgeries were analyzed separately. Patients who were given chemoprophylaxis (treatment) and controls were matched according to known VTE risk factors, including age, body mass index, sex, diabetes, chronic kidney disease, history of VTE, estimated blood loss, length of surgery, transfusion, whether surgery was staged, and whether surgery used an anterior approach. K-nearest neighbor propensity score matching was performed, and the treatment effect of chemoprophylaxis was calculated.

RESULTS

Unadjusted, there was no difference in the rate of VTE between treatment and controls in either population. Baseline clinical and demographic characteristics differed significantly between treatment and control groups. In all, 575 lumbar fusion patients and 435 noninstrumented lumbar decompression patients were successfully propensity score matched, yielding balanced models (Rubin B <25, 0.5<Rubin R <2.0) and >60% reduction in known bias for both populations. The treatment effect of chemoprophylaxis after lumbar fusion in our patient population was a reduction in VTE incidence from 9.4% to 4.2% ( P <0.05), and propensity score adjusted regression confirmed a reduced odds of VTE with chemoprophylaxis (odds ratio=0.37, P =0.035). The treatment effect was not significant for noninstrumented lumbar decompression patients.

CONCLUSION

Among patients undergoing instrumented lumbar fusions, chemoprophylactic anticoagulation causes a significant reduction in VTE, but causes no significant reduction among patients undergoing noninstrumented lumbar decompression.

Cauda Equina Syndrome

Cauda equina syndrome (CES) involves compression of some or all of the lumbar and sacral peripheral nerve roots. However, there is a lack of consensus in the literature regarding the exact diagnosis criteria in this patient population. Much of the pathophysiology has been studied regarding the onset of this condition; however, the long-term effects are not able to be accurately predicted at this time. Recent literature has associated timing to surgical decompression, severity of symptoms at time of onset, and involvement of bladder dysfunction as prognostic indicators of CES.

Complication Avoidance in Surgical Management of Vertebral Column Tumors

The surgical management of spinal tumors has grown increasingly complex as treatment algorithms for both primary bone tumors of the spine and metastatic spinal disease have evolved in response to novel surgical techniques, rising complication rates, and additional data concerning adjunct therapies. In this review, we discuss actionable interventions for improved patient safety in the operative care for spinal tumors. Strategies for complication avoidance in the preoperative, intraoperative, and postoperative settings are discussed for approach-related morbidities, intraoperative hemorrhage, wound healing complications, cerebrospinal fluid (CSF) leak, thromboembolism, and failure of instrumentation and fusion. These strategies center on themes such as pre-operative imaging review and medical optimization, surgical dissection informed by meticulous attention to anatomic boundaries, and fastidious wound closure followed by thorough post-operative care.

Safety of Venous Thromboembolism Prophylaxis Protocol Using a Novel Leg Exercise Apparatus in Bedridden Patients due to Spinal Diseases

Purpose: Venous thromboembolism (VTE) is a complication in patients with a spinal disease requiring bedfast for conservative therapies. We previously developed a novel leg exercise apparatus (LEX) to encourage patients to exercise their lower extremities during bed rest. The purpose of this study was to evaluate the feasibility and safety of the LEX for the prevention of VTE in patients on bed rest due to spinal disease.

Methods: Patients with spinal diseases requiring bed rest were included in the study. Exercise using the LEX was performed for ≥5 minutes. The exercises were performed three or more times per day during the bed rest period. In addition, we evaluated adverse events, such as symptomatic VTE and changes in vital signs, using venous ultrasonography, blood tests, and measurement of vital signs.

Results: In total, 31 patients were enrolled (11 men, 20 women), with mean age, height, weight, and body mass index of 72.4 years, 155.2 cm, 55.0 kg, and 22.6 kg/m², respectively. Twenty-four subjects had spinal fractures. Twenty-nine patients continued exercising until they could leave their beds. No symptomatic VTE was observed in any patient, and no other severe adverse events were observed. There were no significant changes in vital signs. The average number of exercise days with LEX and length of hospitalization were 11 and 31 days, respectively.

Conclusions: This is the first study regarding mechanical thromboprophylaxis through in-bed exercise for patients with bedridden spinal disease. The LEX exercise protocol, in addition to mechanical prophylaxis with graduated compression stockings and intermittent pneumatic compression devices, for the prevention of symptomatic VTE may be feasible and safe for patients with bedridden spinal disease.