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Guideline Summary
Guideline Title
Antithrombotic therapies in spine surgery.
Bibliographic Source(s)
NASS Evidence-based Guideline Development Committee. Antithrombotic therapies in spine surgery. Burr Ridge (IL): North American Spine Society (NASS); 2009. 96 p. [97 references]
Guideline Status

This is the current release of the guideline.

FDA Warning/Regulatory Alert

Note from the National Guideline Clearinghouse: This guideline references a drug(s) for which important revised regulatory and/or warning information has been released.

  • November 6, 2013 – Low Molecular Weight Heparins External Web Site Policy: The U.S. Food and Drug Administration (FDA) is recommending that health care professionals carefully consider the timing of spinal catheter placement and removal in patients taking anticoagulant drugs, such as enoxaparin, and delay dosing of anticoagulant medications for some time interval after catheter removal to decrease the risk of spinal column bleeding and subsequent paralysis after spinal injections, including epidural procedures and lumbar punctures. These new timing recommendations, which can decrease the risk of epidural or spinal hematoma, will be added to the labels of anticoagulant drugs known as low molecular weight heparins, including Lovenox and generic enoxaparin products and similar products.

Scope

Disease/Condition(s)

  • Deep vein thrombosis (DVT)
  • Pulmonary embolism (PE)
  • Venous thromboembolism

Guideline Category
Prevention
Clinical Specialty
Neurological Surgery
Orthopedic Surgery
Preventive Medicine
Intended Users
Advanced Practice Nurses
Nurses
Physician Assistants
Physicians
Guideline Objective(s)

  • To provide evidence-based recommendations to address key clinical questions surrounding the use of antithrombotic therapies in spine surgery
  • To assist in delivering optimum, efficacious treatment with the goal of preventing thromboembolic events

Target Population

Adults (18 years or older) undergoing spine surgery

Interventions and Practices Considered

  1. Antithrombotic therapies
  2. Mechanical prophylaxis
    • Compression stockings
    • Mechanical sequential compression devices
  3. Chemoprophylaxis
    • Warfarin
    • Therapeutic heparin
    • Low molecular weight heparin (LMWH)
    • Clopidogrel
    • Acetylsalicylic acid (ASA) 
  4. Thrombosis embolic deterrent (TED) stockings in combination with ASA

Major Outcomes Considered

  • Incidence of thromboembolic complications of spine surgery
  • Side effects of antithrombotic therapy

Methodology

Methods Used to Collect/Select the Evidence
Searches of Electronic Databases
Description of Methods Used to Collect/Select the Evidence

Identification of Clinical Questions

Trained guideline participants were asked to submit a list of clinical questions that the guideline should address. The lists were compiled into a master list, which was then circulated to each member with a request that they independently rank the questions in order of importance for consideration in the guideline. The most highly ranked questions, as determined by the participants, served to focus the guideline.

Identification of Search Terms and Parameters

One of the most crucial elements of evidence analysis to support development of recommendations for appropriate clinical care is the comprehensive literature search. Thorough assessment of the literature is the basis for the review of existing evidence and the formulation of evidence-based recommendations. In order to ensure a thorough literature search, North American Spine Society (NASS) has instituted a Literature Search Protocol (Appendix C in the original guideline document) which has been followed to identify literature for evaluation in guideline development. In keeping with the Literature Search Protocol, work group members have identified appropriate search terms and parameters to direct the literature search.

Specific search strategies, including search terms, parameters and databases searched, are documented in the appendices (See Appendix D in the original guideline document).

Completion of the Literature Search

After each work group identified search terms/parameters, the literature search was implemented by a medical/research librarian, consistent with the Literature Search Protocol.

Following these protocols ensures that NASS recommendations (1) are based on a thorough review of relevant literature; (2) are truly based on a uniform, comprehensive search strategy; and (3) represent the current best research evidence available. NASS maintains a search history in EndNote,™ for future use or reference.

Review of Search Results/Identification of Literature to Review

Work group members reviewed all abstracts yielded from the literature search and identified the literature they would review in order to address the clinical questions, in accordance with the Literature Search Protocol. Members identified the best research evidence available to answer the targeted clinical questions. That is, if Level I, II and or III literature is available to answer specific questions, the work group was not required to review Level IV or V studies.

Number of Source Documents

Not stated

Methods Used to Assess the Quality and Strength of the Evidence
Expert Consensus (Committee)
Weighting According to a Rating Scheme (Scheme Given)
Rating Scheme for the Strength of the Evidence

Levels of Evidence for Primary Research Question1

  Types of Studies
  Therapeutic Studies — Investigating the results of treatment Prognostic Studies — Investigating the effect of a patient characteristic on the outcome of disease Diagnostic Studies — Investigating a diagnostic test Economic and Decision Analyses — Developing an economic or decision model
Level I
  • High quality randomized trial with statistically significant difference or no statistically significant difference but narrow confidence intervals
  • Systematic Review2 of Level I RCTs (and study results were homogenous3)
  • High quality prospective study4 (all patients were enrolled at the same point in their disease with >80% follow-up of enrolled patients)
  • Systematic review2 of Level I studies
  • Testing of previously developed diagnostic criteria on consecutive patients (with universally applied reference "gold" standard)
  • Systematic review2 of Level I studies
  • Sensible costs and alternatives; values obtained from many studies; with multiway sensitivity analyses
  • Systematic review2 of Level I studies
Level II
  • Lesser quality RCT (e.g., <80% follow-up, no blinding, or improper randomization)
  • Prospective4 comparative study5
  • Systematic review2 of Level II studies or Level I studies with inconsistent results
  • Retrospective6 study
  • Untreated controls from an RCT
  • Lesser quality prospective study (e.g., patients enrolled at different points in their disease or <80% follow-up)
  • Systematic review2 of Level II studies
  • Development of diagnostic criteria on consecutive patients (with universally applied reference "gold" standard)
  • Systematic review2 of Level II studies
  • Sensible costs and alternatives; values obtained from limited studies; with multiway sensitivity analyses
  • Systematic review2 of Level II studies
Level III
  • Case control study7
  • Retrospective6 comparative study5
  • Systematic review2 of Level III studies
  • Case control study7
  • Study of nonconsecutive patients; without consistently applied reference "gold" standard
  • Systematic review2 of Level III studies
  • Analyses based on limited alternatives and costs; and poor estimates
  • Systematic review2 of Level III studies
Level IV Case Series8 Case Series
  • Case-control study
  • Poor reference standard
  • Analyses with no sensitivity analyses
Level V Expert Opinion Expert Opinion Expert Opinion Expert Opinion

RCT = randomized controlled trial

1 A complete assessment of quality of individual studies requires critical appraisal of all aspects of the study design.

2 A combination of results from two or more prior studies.

3 Studies provided consistent results.

4 Study was started before the first patient enrolled.

5 Patients treated one way (e.g., cemented hip arthroplasty) compared with a group of patients treated in another way (e.g., uncemented hip arthroplasty) at the same institution.

6 The study was started after the first patient enrolled.

7 Patients identified for the study based on their outcome, called "cases"; e.g., failed total arthroplasty, are compared to those who did not have outcome, called "controls"; e.g., successful total hip arthroplasty.

8 Patients treated one way with no comparison group of patients treated in another way.

Methods Used to Analyze the Evidence
Systematic Review with Evidence Tables
Description of the Methods Used to Analyze the Evidence

Evidence Analysis

Members of the work group independently developed evidentiary tables summarizing study conclusions, identifying strengths and weaknesses and assigning levels of evidence. In order to systematically control for potential biases, at least two work group members reviewed each article selected and independently assigned levels of evidence to the literature using the North American Spine Society (NASS) levels of evidence. Any discrepancies in scoring have been addressed by two or more reviewers. The consensus level (the level upon which two thirds of reviewers were in agreement) was then assigned to the article.

As a final step in the evidence analysis process, members identified and documented gaps in the evidence to educate guideline readers about where evidence is lacking and help guide further needed research by NASS and other societies.

Methods Used to Formulate the Recommendations
Expert Consensus (Nominal Group Technique)
Description of Methods Used to Formulate the Recommendations

Identification of Work Groups

Multidisciplinary teams were assigned to work groups and assigned specific clinical questions to address. Because North American Spine Society (NASS) is comprised of surgical, medical and interventional specialists, it is imperative to the guideline development process that a cross section of NASS membership is represented on each group whenever feasible. This also helps to ensure that the potential for inadvertent biases in evaluating the literature and formulating recommendations is minimized.

Formulation of Evidence-Based Recommendations and Incorporation of Expert Consensus

Work groups held Web casts to discuss the evidence-based answers to the clinical questions, the grades of recommendations and the incorporation of expert consensus. Expert consensus has been incorporated only where Level I-IV evidence is insufficient and the work group has deemed that a recommendation is warranted. Transparency in the incorporation of consensus is crucial, and all consensus-based recommendations made in this guideline very clearly indicate that Level I-IV evidence is insufficient to support a recommendation and that the recommendation is based only on expert consensus.

Consensus Development Process

Voting on guideline recommendations was conducted using a modification of the nominal group technique in which each work group member independently and anonymously ranked a recommendation on a scale ranging from 1 ("extremely inappropriate") to 9 ("extremely appropriate").

Consensus was obtained when at least 80% of work group members ranked the recommendation as 7, 8 or 9. When the 80% threshold was not attained, up to three rounds of discussion and voting were held to resolve disagreements. If disagreements were not resolved after these rounds, no recommendation was adopted.

After the recommendations were established, work group members developed the guideline content, addressing the literature which supports the recommendations.

Rating Scheme for the Strength of the Recommendations

Grades of Recommendation for Summaries or Reviews of Studies

A. Good evidence (Level I studies with consistent finding) for or against recommending intervention.

B. Fair evidence (Level II or III studies with consistent findings) for or against recommending intervention.

C. Poor quality evidence (Level IV or V studies) for or against recommending intervention.

I. Insufficient or conflicting evidence not allowing a recommendation for or against intervention.

Cost Analysis

A formal cost analysis was not performed and published cost analyses were not reviewed.

Method of Guideline Validation
External Peer Review
Internal Peer Review
Description of Method of Guideline Validation

Submission of the Draft Guidelines for Review/Comment

Guidelines were submitted to the full Evidence- based Guideline Development Committee, the Research Council Director and the Advisory Panel for review and comment. The Advisory Panel is comprised of representatives from physical medicine and rehab, pain medicine/management, orthopedic surgery, neurosurgery, anesthesiology, rheumatology, psychology/psychiatry and family practice. Revisions to recommendations were considered for incorporation only when substantiated by a preponderance of appropriate level evidence.

Submission for Board Approval

Once any evidence-based revisions were incorporated, the drafts were prepared for North American Spine Society (NASS) Board review and approval. Edits and revisions to recommendations and any other content were considered for incorporation only when substantiated by a preponderance of appropriate level evidence.

Recommendations

Major Recommendations

The grades of recommendations (A-C, I) and levels of evidence (I-V) are defined at the end of the "Major Recommendations" field.

Recommendations for Appropriate Antithrombotic Therapies in Spine Surgeries

  1. Efficacy of Antithrombotic Therapies

    Do prophylactic antithrombotic measures, including compression stockings, mechanical sequential compression devices and chemoprophylaxis medications, decrease the rate of clinically symptomatic deep vein thrombosis (DVT) and/or pulmonary embolism (PE) (including fatal pulmonary embolism) following elective spinal surgery?

    Mechanical compression devices in the lower extremities are suggested in elective spinal surgery to decrease the incidence of thromboembolic complications.

    Grade of Recommendation: B

    Thrombosis embolic deterrent (TED) stockings in combination with acetylsalicylic acid (ASA) are an option in elective spinal surgery to decrease the incidence of thromboembolic complications.

    Grade of Recommendation: I (Insufficient Evidence)

    Most commonly-performed elective spine surgeries done through a posterior approach are associated with a very low risk of venous thromboembolism (VTE). In this setting, chemoprophylaxis may not be warranted as it is accompanied by a definable risk of serious wound and bleeding complications. Low molecular weight heparin (LMWH) or low-dose warfarin may be used postoperatively to lower the risk of thromboembolic complications following elective combined anterior-posterior (circumferential) spine surgery or in patients identified as having a high risk for thromboembolic disease, such as multiple trauma, malignancy or hypercoagulable state. These therapies should be considered carefully and on an individual case-by-case basis, as use may place patients at increased risk of bleeding complications.

    Grade of Recommendation: Work Group Consensus Statement

  1. Mechanical Prophylaxis

    When indicated, what is the ideal time to begin mechanical prophylaxis in relation to spinal surgery?

    When indicated, how long should mechanical prophylaxis continue following spinal surgery?

    Although evidence in the spine literature is limited regarding timing and duration of mechanical prophylaxis, initiation of mechanical compression just prior to or at the beginning of surgery and continuation until the patient is fully ambulatory is a reasonable practice. While several studies cited start and stop times consistent with this recommendation, no studies specifically assessed this issue in a comparative fashion.

    Grade of Recommendation: Work Group Consensus Statement

  1. Chemoprophylaxis

    The utility and safety of chemoprophylaxis following spinal surgery is controversial. Because of the hazardous risk of symptomatic epidural hematoma, the potential consequences may confound the benefits of these agents. Unfortunately, scientific scrutiny of chemoprophylaxis in elective spinal surgery has been limited to case series involving discectomy and decompression. Evidence is better established in higher risk patients undergoing spinal surgery for traumatic or neoplastic conditions, although safety and efficacy have not been thoroughly studied in these conditions either. Most commonly-performed elective spine surgeries done through a posterior approach are associated with a very low risk of venous thromboembolism. In this setting, chemoprophylaxis may not be warranted as it is accompanied by a definable risk of serious wound and bleeding complications. When chemoprophylaxis is utilized, neurological status should be closely monitored.

    Grade of Recommendation: Work Group Consensus Statement

    When indicated, what is the ideal time to begin chemoprophylaxis in relation to spinal surgery?

    Although the literature does not support an ideal time to begin chemoprophylaxis, initiating LMWH preoperatively can decrease the incidence of thromboembolic disease. However, this is associated with an increased risk of bleeding complications. There is Level IV evidence that LMWH can be started safely the day of elective spine surgery.  It is the work group's recommendation that LMWH be used cautiously prior to routine, elective spinal surgery, and withheld unless there are other risk factors for thromboembolism.

    Grade of Recommendation: Work Group Consensus Statement

    When indicated, how long should chemoprophylaxis be continued following spinal surgery?

    The available literature does not support an ideal duration for which chemoprophylaxis should be continued following spinal surgery. It is the work group's recommendation that this parameter be decided based upon the underlying pathological condition being treated, comorbidities (e.g., heart valve, previous deep vein thrombosis, stent restenosis prophylaxis), and other host factors, such as ambulatory and neurological status.

    Grade of Recommendation: Work Group Consensus Statement

    In patients who are being treated with chemical anticoagulants for a non-spine related disorder (e.g., valve replacement), what is the ideal "bridge" therapy between stopping and starting the usual agent before and after surgery?

    The literature reviewed does not support an ideal perioperative "bridge" therapy. Candidate agents, such as warfarin, therapeutic heparin, LMWH, clopidogrel or acetylsalicylic acid all increase bleeding risk in postoperative spinal surgery patients. It is the work group's recommendation that the magnitude of surgical insult and underlying thromboembolic risk be balanced against the risk for epidural bleeding and wound complications. Though not substantiated by evidence, the work group agreed that the use of intravenous heparin is a reasonable bridge therapy for those patients being indefinitely treated with warfarin for a non-spine condition. The rationale for this statement is that intravenous heparin is more controllable and more predictable than LMWH, though LMWH is a reasonable alternative bridge therapy. The ideal time to discontinue agents such as clopidogrel and acetylsalicylic acid is unique to the pharmacokinetics of the particular medication as it is influenced by the clearance half-life, however, an interval of approximately one week prior to surgery seems prudent.

    Grade of Recommendation: Work Group Consensus Statement

Definitions:

Grades of Recommendation

A. Good evidence (Level I studies with consistent finding) for or against recommending intervention.

B. Fair evidence (Level II or III studies with consistent findings) for or against recommending intervention.

C. Poor quality evidence (Level IV or V studies) for or against recommending intervention.

I. Insufficient or conflicting evidence not allowing a recommendation for or against intervention.

Levels of Evidence for Primary Research Question1

Types of Studies
Therapeutic Studies — Investigating the results of treatment Prognostic Studies — Investigating the effect of a patient characteristic on the outcome of disease Diagnostic Studies — Investigating a diagnostic test Economic and Decision Analyses — Developing an economic or decision model
Level I
  • High quality randomized trial with statistically significant difference or no statistically significant difference but narrow confidence intervals
  • Systematic Review2 of Level I RCTs (and study results were homogenous3)
  • High quality prospective study4 (all patients were enrolled at the same point in their disease with >80% follow-up of enrolled patients)
  • Systematic review2 of Level I studies
  • Testing of previously developed diagnostic criteria on consecutive patients (with universally applied reference "gold" standard)
  • Systematic review2 of Level I studies
  • Sensible costs and alternatives; values obtained from many studies; with multiway sensitivity analyses
  • Systematic review2 of Level I studies
Level II
  • Lesser quality RCT (e.g., <80% follow-up, no blinding, or improper randomization)
  • Prospective4 comparative study5
  • Systematic review2 of Level II studies or Level I studies with inconsistent results
  • Retrospective6 study
  • Untreated controls from an RCT
  • Lesser quality prospective study (e.g., patients enrolled at different points in their disease or <80% follow-up)
  • Systematic review2 of Level II studies
  • Development of diagnostic criteria on consecutive patients (with universally applied reference "gold" standard)
  • Systematic review2 of Level II studies
  • Sensible costs and alternatives; values obtained from limited studies; with multiway sensitivity analyses
  • Systematic review2 of Level II studies
Level III
  • Case control study7
  • Retrospective6 comparative study5
  • Systematic review2 of Level III studies
  • Case control study7
  • Study of nonconsecutive patients; without consistently applied reference "gold" standard
  • Systematic review2 of Level III studies
  • Analyses based on limited alternatives and costs; and poor estimates
  • Systematic review2 of Level III studies
Level IV Case Series8 Case Series
  • Case-control study
  • Poor reference standard
  • Analyses with no sensitivity analyses
Level V Expert Opinion Expert Opinion Expert Opinion Expert Opinion

RCT = randomized controlled trial

1 A complete assessment of quality of individual studies requires critical appraisal of all aspects of the study design.

2 A combination of results from two or more prior studies.

3 Studies provided consistent results.

4 Study was started before the first patient enrolled.

5 Patients treated one way (e.g., cemented hip arthroplasty) compared with a group of patients treated in another way (e.g., uncemented hip arthroplasty) at the same institution.

6 The study was started after the first patient enrolled.

7 Patients identified for the study based on their outcome, called "cases"; e.g., failed total arthroplasty, are compared to those who did not have outcome, called "controls"; e.g., successful total hip arthroplasty.

8 Patients treated one way with no comparison group of patients treated in another way.

Clinical Algorithm(s)

None provided

Evidence Supporting the Recommendations

Type of Evidence Supporting the Recommendations

The type of supporting evidence is identified and graded for the recommendations (see the "Major Recommendations" field).

Benefits/Harms of Implementing the Guideline Recommendations

Potential Benefits

  • Appropriate prophylaxis against thromboembolic complications of spine surgery
  • Reduction in the incidence of thromboembolic complications in spine surgery

Potential Harms

 

  • Elective spine surgeries done through a posterior approach are associated with a very low risk of venous thromboembolism (VTE). In this setting, chemoprophylaxis may not be warranted as it is accompanied by a definable risk of serious wound and bleeding complications.
  • Low molecular weight heparin (LMWH) or low-dose warfarin should be considered carefully and on an individual case-by-case basis, as use may place patients at increased risk of bleeding complications.
  • The utility and safety of chemoprophylaxis following spinal surgery is controversial. Because of the hazardous risk of symptomatic epidural hematoma, the potential consequences may confound the benefits of these agents.
  • Initiating LMWH preoperatively can decrease the incidence of thromboembolic disease. However, this is associated with an increased risk of bleeding complications.
  • Warfarin, therapeutic heparin, LMWH, clopidogrel or acetylsalicylic acid all increase bleeding risk in postoperative spinal surgery patients.

 

Qualifying Statements

Qualifying Statements

  • This guideline does not represent a "standard of care," nor is it intended as a fixed treatment protocol. It is anticipated that there will be patients who will require less or more extensive prophylaxis than the average. It is also acknowledged that in atypical cases, treatment falling outside this guideline will sometimes be necessary. This guideline should not be seen as prescribing the type, frequency or duration of intervention. Treatment should be based on the individual patient's need and doctor's professional judgment. This document is designed to function as a guideline and should not be used as the sole reason for denial of treatment and services. This guideline is not intended to expand or restrict a health care provider's scope of practice or to supersede applicable ethical standards or provisions of law.
  • The clinical guideline should not be construed as including all proper methods of care or excluding other acceptable methods of care reasonably directed to obtaining the same results. The ultimate judgment regarding any specific procedure or treatment is to be made by the physician and patient in light of all circumstances presented by the patient and the needs and resources particular to the locality or institution.
  • The North American Spine Society believes that deliberately withholding antithrombotic therapies, thereby exposing patients to increased risks of deep venous thrombosis (DVT) and pulmonary embolism (PE) in order to more thoroughly investigate the rate of DVT/PE in an unprophylaxed patient population undergoing nonelective spine surgery is unethical.

Implementation of the Guideline

Description of Implementation Strategy

The recommendations will be reviewed by a group experienced in performance measure development (e.g., the American Medical Association [AMA] Physician's Consortium for Performance Improvement) to identify those recommendations rigorous enough for measure development.

Institute of Medicine (IOM) National Healthcare Quality Report Categories

IOM Care Need
Staying Healthy
IOM Domain
Effectiveness
Safety

Identifying Information and Availability

Bibliographic Source(s)
NASS Evidence-based Guideline Development Committee. Antithrombotic therapies in spine surgery. Burr Ridge (IL): North American Spine Society (NASS); 2009. 96 p. [97 references]
Adaptation

Not applicable: The guideline was not adapted from another source.

Date Released
2009
Guideline Developer(s)
North American Spine Society - Medical Specialty Society
Source(s) of Funding

North American Spine Society (NASS)

Guideline Committee

North American Spine Society (NASS) Evidence-based Guideline Development Committee

Composition of Group That Authored the Guideline

Committee Members: Christopher M. Bono, MD, Committee Chair; William C. Watters III, MD, Committee Chair; Michael H. Heggeness, MD, PhD; Daniel K. Resnick, MD; William O. Shaffer, MD; Jamie Baisden, MD; Peleg Ben-Galim, MD; John E. Easa, MD; Robert Fernand, MD; Tim Lamer, MD; Paul G. Matz, MD; Richard C. Mendel, MD; Rajeev K. Patel, MD; Charles A. Reitman, MD; John F. Toton, MD

Financial Disclosures/Conflicts of Interest

All participating authors have submitted a disclosure form relative to potential conflicts of interest which is kept on file at North American Spine Society (NASS).

Guideline Status

This is the current release of the guideline.

Guideline Availability

Electronic copies: in Portable Document Format (PDF) from the North American Spine Society (NASS) Web site External Web Site Policy.

Print copies: Available from the North American Spine Society (NASS), 7075 Veterans Boulevard, Burr Ridge, IL 60527; Toll-free: (866) 960-6277. An order form is available from the North American Spine Society Web site External Web Site Policy.

Availability of Companion Documents

None available

Patient Resources

None available

NGC Status

This NGC summary was completed by ECRI Institute on November 24, 2009. The information was verified by the guideline developer on December 21, 2009. This summary was updated by ECRI Institute on May 17, 2010 following the U.S. Food and Drug Administration advisory on Plavix (clopidogrel). This summary was updated by ECRI Institute on July 27, 2010 following the FDA drug safety communication on Heparin. This summary was updated by ECRI Institute on March 7, 2014 following the U.S. Food and Drug Administration advisory on Low Molecular Weight Heparins.

Copyright Statement

Full-text guidelines can only be acquired through the North American Spine Society (NASS). Questions regarding use and reproduction should be directed to NASS, attention Belinda Duszynski, Research Manager.

Disclaimer

NGC Disclaimer

The National Guideline Clearinghouse™ (NGC) does not develop, produce, approve, or endorse the guidelines represented on this site.

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