Volume 4. AAOS Clinical Guideline on Preventing Venous

18 Pages·2011·0.1 MB·English

by  Sluka, Patrick

Volume 4.
AAOS Clinical Guideline on Preventing Venous
Thromboembolic Disease in Patients Undergoing
Elective Hip and Knee Arthroplasty
Comparison with Other Guidelines
Disclaimer
This clinical guideline was developed by an AAOS physician volunteer Work Group and
experts in systematic reviews. It is provided as an educational tool based on an
assessment of the current scientific and clinical information and accepted approaches to
treatment. The recommendations in this guideline are not intended to be a fixed protocol
as some patients may require more or less treatment or different means of diagnosis.
Patients seen in clinical practice may not be the same as those found in a clinical trial.
Patient care and treatment should always be based on a clinician’s independent medical
judgment given the individual clinical circumstances.
Disclosure Requirement
In accordance with AAOS policy, all individuals whose names appear as authors or
contributors to this clinical practice guideline filed a disclosure statement as part of the
submission process. All panel members provided full disclosure of potential conflicts of
interest prior to beginning work on the recommendations contained within this clinical
practice guideline.
Funding Source
The American Academy of Orthopaedic Surgeons exclusively funded this clinical
practice guideline. The Academy received no funding from outside commercial sources
to support the development of this document.
FDA Clearance
Some drugs or medical devices referenced or described in this clinical practice guideline
may not have been cleared by the Food and Drug Administration (FDA) or may have
been cleared for a specific use only. The FDA has stated that it is the responsibility of the
physician to determine the FDA clearance status of each drug or device he or she wishes
to use in clinical practice.
Copyright
All rights reserved. No part of this clinical practice guideline may be reproduced, stored
in a retrieval system, or transmitted, in any form, or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without prior written permission
from the AAOS.
Published 2011 by the American Academy of Orthopaedic Surgeons
6300 North River Road
Rosemont, IL 60018
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Second Edition
Copyright 2011 by the American Academy of Orthopaedic Surgeons
COMPARISON WITH PRIOR GUIDELINES/AHRQ REVIEW
Several guidelines on this topic have previously been published, including the prior
AAOS guideline from 2007,1 the American College of Chest Physicians (ACCP)
guideline from 2008,2 and the National Institute for Health and Clinical Excellence
(NICE) guideline from 2010.3 In addition, the Agency for Healthcare Research and
Quality (AHRQ) has published a draft systematic review on this topic in 2011.4 The
following pages compare and contrast the current AAOS guideline with these prior
publications.
COMPARING REVIEW METHODS
INCLUSION CRITERIA
The major differences in inclusion criteria include the differences in the time period for
eligible studies, the minimum number of patients allowed in a study, the outcomes
considered for inclusion, and the patient populations considered. Another major
difference is that the prior AAOS guideline was mainly consensus-based; only the
recommendations for chemoprophylaxis were based on a systematic review of the
literature.
The time period of eligible studies for the current AAOS guidelines was 1966 – February
2011. This compares to 1980 – September 2010 for the AHRQ review, 1950 – December
2008 for the NICE guideline, 1966 – May 2006 (the 2008 guideline updated the search
from the prior edition of the guidelines) for the ACCP guideline, and 1996 – August 2006
for the prior AAOS guideline.
The minimum number of patients needed for a study to be included for the current AAOS
guideline was 100 patients enrolled per arm for the outcomes PE, DVT, and mortality,
and 10 patients per arm for other outcomes. The AHRQ review included controlled trials
of any size and controlled observational studies of at least 750 patients. The NICE
guideline appeared to include studies of any size, the ACCP guideline included studies of
at least 10 patients per arm, and the prior AAOS guideline included randomized trials of
at least 10 patients per arm and prospective studies of at least 100 patients.
For outcomes considered, a major difference is that the prior AAOS guideline did not
consider DVT, while the other guidelines and reviews did. Also, the current AAOS
guideline, while using DVT as an outcome, did not consider DVT to be a critical
outcome.
In terms of patient populations, all guidelines and reviews included elective hip and knee
arthroplasty patients. Only the AHRQ also considered hip fracture patients in the same
analyses with elective arthroplasty patients. ACCP and NICE analyzed hip and knee
patients separately. The current AAOS guideline analyzed hip and knee patients both
separately and together, as did AHRQ. For major bleeding only, the NICE analysis
pooled studies across all included populations of surgical and hospitalized medical
patients.
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The article inclusion criteria in these various sources are summarized in Table 1.
Table 1 Article Inclusion Criteria
Guideline/Review Dates Minimum N* Outcomes Patients
All reported
1966- 100/arm for PE, DVT, outcomes (but
Feb, and mortality; 10 for DVT not a Elective hip and knee
AAOS (Current) 2011 all other outcomes critical outcome) arthroplasty
Any size for
1980- controlled trials, 750 Elective hip and knee
Sept, patients for controlled All reported and hip fracture
AHRQ (2011) 2010 observational studies outcomes patients
Elective hip and knee
and, for major
1950- bleeding, also
Dec, All reported surgical and
NICE (2010) 2008 Any size outcomes hospitalized patients
1966-
May, All reported
ACCP (2008) 2006 10 patients per arm outcomes Elective hip and knee
All patient-
10 patients/arm for oriented
1996- RCTS, 100 patients outcomes (does
Aug, for all other not include Elective hip and knee
AAOS (2007) 2006 prospective trials DVT) arthroplasty
*Minimum N refers to the smallest number of patients in any included trial.
QUALITY ASSESSMENT
The AHRQ review evaluated individual study quality as good, fair, or poor, according to
a quality checklist specific to study design. The overall strength of evidence was graded
as high, moderate, low, or insufficient based on four domains: risk of bias, consistency,
directness, and precision. The applicability of each study and of the body of evidence was
also determined, with more applicable studies labeled as effectiveness studies and less
applicable studies labeled efficacy studies. The NICE guideline used the Scottish
Intercollegiate Guidelines Network (SIGN) system for ranking the evidence and included
studies of the highest available evidence. For example, if a high-quality systematic
review, meta-analysis, or randomized controlled trial was found, lower quality studies
were not included. The reviewers first determined the design of a study and then rated the
quality of each study using a quality checklist specific to the study design. The ACCP
guideline rated study quality by assessing randomization, allocation concealment,
blinding, completeness of follow-up, and intention-to-treat analysis. The quality of the
body of evidence was rated A, B, or C, based on the quality of the studies as well as the
consistency and precision of results, the directness of the evidence, and the probability of
reporting bias. The prior AAOS guideline rated individual studies in a manner similar to
that of the AHRQ review, while the body of evidence was rated based on a level of
evidence system largely based on study design.
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In each of these quality assessment systems, as well as that used for the current AAOS
guideline, arriving at a final score is subjective and arbitrary. However, only the current
AAOS system explicitly used a scoring system in which highly specific criteria
determined what answer would be given to any given quality-related question.
STATISTICAL METHODS
For questions addressed by sufficient data, AHRQ conducted traditional meta-analyses.
They did not performed network meta-analyses. The AHRQ review involved a series of
analyses, first grouping all pharmacologic agents together to compare to no prophylaxis
and grouping all mechanical devices together to compare to no prophylaxis. Then
interclass comparisons of agents were performed, followed by intraclass comparisons.
Like the current AAOS guideline, the NICE guideline performed network meta-analyses
of the thromboprophylaxis literature. NICE grouped all low-molecular-weight heparins
(LMWH) together in their analysis, while AAOS did not. Both guidelines grouped foot
pumps with intermittent pneumatic compression devices in these analyses. For major
bleeding, NICE grouped mechanical devices with no prophylaxis. ACCP relied on
previously published pooled estimated from high-quality systematic reviews or
conducted traditional meta-analysis to obtain pooled estimates for specific questions. The
prior AAOS guideline, due to the rarity of events, conducted meta-analyses to estimate
the incidence of each outcome according to treatment. These analyses were used to
indirectly compare event rates by treatment.
GRADING RECOMMENDATIONS
Being a systematic review, The AHRQ review did not make recommendations; it only
summarized the available evidence. The NICE guideline did not assign a grade to their
recommendation but tried to convey its strength through the wording and discussion of
the recommendation. ACCP used a grading system based on the Grading of
Recommendations Assessment, Development and Evaluation (GRADE) system. The
guideline used two levels of recommendation: grade 1 for strong recommendations (“we
recommend”) and grade 2 for weak recommendations (“we suggest”). This differs from
the current AAOS system which uses a third level for moderate recommendations, with
the corresponding language of “we suggest”, while “the practitioner might” is the phrase
used for weak recommendations. Each recommend is therefore labeled for strength of
recommendation (1 or 2) and quality of evidence (A, B, or C). The prior AAOS guideline
graded recommendations A, B, or C, based on good, fair, or poor evidence, respectively.
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COMPARING RECOMMENDATIONS
Here we compare the recommendations of other guidelines to those in the current
guideline. First, the current AAOS recommendation is stated, followed by a table
summarizing the corresponding recommendation from the prior AAOS guideline, the
ACCP guideline, and the NICE guideline. While the AHRQ review did not make
recommendations, we summarize its findings for each of the recommendations it
addressed. Following the table, we discuss any differences between the guidelines.
1. We recommend against routine post-operative duplex ultrasonography screening
of patients who undergo elective hip or knee arthroplasty. (Grade of
Recommendation: Strong)
Grade of
Other Guidelines Results Recommendation
Grade B; Consensus
Prior AAOS Guideline (2007) Agrees with recommendation recommendation
ACCP (2008) Agrees with recommendation Grade 1A
NICE (2010) Does not address n/a
AHRQ (2011) Does not address n/a

Comment: Among guidelines addressing routine screening, there are no differences.
NICE and AHRQ do not address this topic.

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2. Patients undergoing elective hip or knee arthroplasty are already at high risk for
venous thromboembolism. The practitioner might further assess the risk of venous
thromboembolism by determining whether these patients had a previous venous
thromboembolism. (Grade of Recommendation: Weak) Current evidence is not
clear about whether factors other than a history of previous venous
thromboembolism increase the risk of venous thromboembolism in patients
undergoing elective hip or knee arthroplasty and, therefore, we cannot
recommend for or against routinely assessing these patients for these factors.
(Grade of Recommendation: Inconclusive)
Other Grade of
Guidelines Results Recommendation
Prior AAOS Recommends risk-stratification for PE – gives examples Grade B;
Guideline but does not specify complete list of risk factors; Consensus
(2007) guideline does not address DVT recommendation
Does not explicitly make a recommendation; notes all
ACCP (2008) TKA and THA patients considered high risk for VTED n/a
Considers all TKA and THA patients as at elevated risk NICE does not
for VTED; Does not make a recommendation regarding formally assign
NICE (2010) further risk stratification grades
Notes limited data and lists characteristics that have been
associated with VTED in a study using multivariate
AHRQ (2011) regression analysis n/a

Comment: While the present AAOS guideline concurs with NICE and ACCP in that all
THA and TKA patients are at elevated risk for VTED, the current AAOS guideline
further suggests that patients with a previous history of VTE are of even more concern.
NICE and ACCP did not specifically address whether prior VTED or other factors further
increase the risk beyond the already high risk due to THA/TKA.

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3. Patients undergoing elective hip or knee arthroplasty are at risk for bleeding and
bleeding-associated complications. In the absence of reliable evidence, it is the
opinion of this work group that patients be assessed for known bleeding disorders
like hemophilia and for the presence of active liver disease which further increase
the risk for bleeding and bleeding-associated complications. (Grade of
Recommendation: Consensus) Current evidence is not clear about whether
factors other than the presence of a known bleeding disorder or active liver
disease increase the chance of bleeding in these patients and, therefore, we are
unable to recommend for or against using them to assess a patient’s risk of
bleeding. (Grade of Recommendation: Inconclusive)
Other Grade of
Guidelines Results Recommendation
Prior AAOS Grade C;
Guideline Recommends risk-stratification – gives examples but Consensus
(2007) does not specify complete list of risk factors recommendation
Does not make a specific recommendation regarding
risk-stratification for bleeding but alters recommended
ACCP (2008) thromboprophylaxis for patients at high risk of bleeding n/a
Recommends assessing bleeding risk; among patients
with a bleeding risk factor, recommends withholding NICE does not
pharmacological prophylaxis if bleeding risk outweighs formally assign
NICE (2010) VTED risk (consensus) grades
AHRQ (2011) Found no data n/a

Comment: The prior AAOS guideline and the NICE guideline made their
recommendations based on consensus. ACCP does not directly make a recommendation,
although its thromboprophylaxis recommendation does separate out patients at high risk
of bleeding. Like AHRQ, we found a lack of evidence addressing the topic, so we
refrained from making a recommendation except for the two factors for which there was
direct, albeit very low quality, evidence among elective hip or knee arthroplasty patients.

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4. We suggest that patients discontinue antiplatelet agents (e.g., aspirin, clopidogrel)
before undergoing elective hip or knee arthroplasty. (Grade of
Recommendation: Moderate)
Other Grade of
Guidelines Results Recommendation
Prior AAOS
Guideline (2007) Does not address n/a
Addresses in a separate publication:5 Does not make a
specific recommendation on whether to discontinue:
discusses risk- stratifying patients (if low risk for
cardiovascular event, can discontinue) For patients who
do requiring stopping antiplatelet therapy, recommends
ACCP (2008) stopping 7-10 days before surgery. n/a
Recommends assessing the risks and benefits of
stopping pre-existing established antiplatelet therapy 1 NICE does not
week before surgery. Also recommends considering formally assign
NICE (2010) involving the multidisciplinary team in the assessment. grades
AHRQ (2011) Does not address n/a

Comment: ACCP discusses the factors to consider when making the decision regarding
discontinuation of antiplatelet therapy but does not make a recommendation. Similarly,
NICE only recommends assessing the risks and benefits of discontinuing antiplatelet
therapy, rather than recommending discontinuation outright. Neither guideline’s
discussion of the issue is specific to elective hip or knee arthroplasty patients. AHRQ and
the prior AAOS guideline do not address this topic.

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5. We suggest the use of pharmacologic agents and/or mechanical compressive
devices for the prevention of venous thromboembolism in patients undergoing
elective hip or knee arthroplasty, and who are not at elevated risk beyond that of
the surgery itself for venous thromboembolism or bleeding. (Grade of
Recommendation: Moderate) Current evidence is unclear about which
prophylactic strategy (or strategies) is/are optimal or suboptimal. Therefore, we
are unable to recommend for or against specific prophylactics in these patients.
(Grade of Recommendation: Inconclusive) In the absence of reliable evidence
about how long to employ these prophylactic strategies, it is the opinion of this
work group that patients and physicians discuss the duration of prophylaxis.
(Grade of Recommendation: Consensus)
Other
Guidelines Results Grade of Recommendation
Grade B for choice of agent, Grade
Pharmacological prophylaxis: C for dosage and timing
Prior • For patients at standard risk of bleeding and PE,
AAOS recommends aspirin, LMWH, warfarin, or synthetic Mechanical prophylaxis (Consensus
Guideline pentasaccharides (recommended duration varies by agent) recommendation): Grade B for use,
(2007) Mechanical prophylaxis: recommends (consensus) Grade C for duration
Choice of agents: Grade 1A, except
IPC as alternative in knee patients is
Elective hip replacement recommendations: Grade 1B, not using foot pump as
• Use LMWH, fondaparinux, or adjusted-dose vitamin K sole method in knee patients is
antagonist (VKA) (dosage and timing specified for each Grade 1B
drug)
• Do not use aspirin, heparin, graduated compression Duration: Grade 1A for at least 10
stockings (GCS), or foot pump as sole prophylaxis method days; extended duration is 1A for
Elective knee replacement recommendations: hip and 2B for knee; each
• Same as hip except IPC is an alternative to anticoagulant recommended agent also has a
prophylaxis (also doesn’t recommend against GCS alone) separate grade for extended
Other major orthopedic surgery recommendations: duration:
• Timing (discussion is of tradeoff between efficacy and LMWH: Grade 1A – hip, 1C – knee
bleeding) VKA: Grade 1B – hip, 1C – knee
ACCP • Duration: at least 10 days; extend beyond 10 days and up Fondaparinux: Grade 1C – hip and
(2008) to 35 days (recommended for hip, suggested for knee) knee
Recommends combined mechanical and pharmacological methods:
• Mechanical: start at admission and continue until patient
no longer has reduced mobility; use GCS, foot impulse
devices, or IPC
• Pharmacological: start after surgery (specific timing given
separately for each drug) and continue for 28-35 days for
hip patients and 10-14 days for knee patients: Dabigatran,
NICE Fondaparinux, LMWH, Rivaroxaban, unfractionated NICE does not formally assign
(2010) heparin (UFH) (for patients with renal failure) grades
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Other
Guidelines Results Grade of Recommendation
Any prophylaxis vs. no prophylaxis
• Pharmacologic prophylaxis:
o reduces DVT and increases minor bleeding
(moderate evidence)
o no reduction in symptomatic DVT, major
bleeding, nonfatal PE, mortality, fatal PE, fatal
bleeding, major bleeding leading to reoperation
(low level evidence)
o no reduction in PE unless limit to trials not
allowing any background prophylaxis (stockings)
in either group
o no data for other outcomes, including PTS
• Mechanical prophylaxis:
o reduces overall DVT, no reduction in proximal or
distal DVT (low level evidence)
o no data for other outcomes
Comparing classes of agents
• LMWHs better than heparin for PE, major bleeding,
proximal DVT, and DVT (for THA; opposite result among
hip fracture surgery (HFS) for PE and DVT); heparin also
worse than direct thrombin inhibitors and mechanical
prophylaxis for DVT
• In base case (THA, TKA, HFS), not many interclass
differences for symptomatic outcomes
• In THA alone, LMWHs better than factor Xa inhibitors for
nonfatal PE and symptomatic DVT; but factor Xa
inhibitors better than LMWHs for DVT (and proximal
DVT for TKA and HFS) in each surgery
• LMWHs better than vitamin K antagonists for DVT
• Mechanical better than oral antiplatelets for DVT
• Major bleeding: LMWHs better than factor Xa inhibitors,
worse than vitamin K antagonists
• Observational studies: one found oral vitamin K antagonist
better than oral antiplatelets for fatal PE (only RCT had
same direction, but not significant)
Intraclass comparisons
• Not much data, especially for symptomatic outcomes
• Only significant difference: IPC better than GCS for DVT
Combined pharmacologic and mechanical vs. single modality
• Lack of data, except for DVT
• For DVT: moderate evidence that pharmacologic and
mechanical better than pharmacologic alone
Duration of prophylaxis
• Prolonged prophylaxis reduced PE, symptomatic DVT and
AHRQ DVT, andincreased minor bleeding
(2011) n/a
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