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Prevention of Venous Thromboembolism in Nonorthopedic Surgical Patients ----- Copyright: American College of Chest Physicians 2012 © Antithrombotic Therapy.

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Presentation on theme: "Prevention of Venous Thromboembolism in Nonorthopedic Surgical Patients ----- Copyright: American College of Chest Physicians 2012 © Antithrombotic Therapy."— Presentation transcript:

1 Prevention of Venous Thromboembolism in Nonorthopedic Surgical Patients ----- Copyright: American College of Chest Physicians 2012 © Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

2 Learning Objectives Describe a formal methodology for the evidence- based development of clinical practice guidelines Review select studies of venous thromboembolism (VTE) prevention in surgical patients, as well as the limitations of the studies Summarize recommendations for VTE prevention in specific surgical populations

3 VTE Thrombosis: the formation or presence of a blood clot within a blood vessel Merriam-Webster’s Medical Dictionary Embolism: obstruction or occlusion of a vessel by a transported clot or vegetation, a mass of bacteria, or other … material Stedman’s Medical Dictionary

4 Deep Vein Thrombosis (DVT)

5 Pulmonary Embolism (PE) Goldhaber SZ. N Engl J Med. 1998;339(2):93-104.

6 Pulmonary Angiography Bliss et al. N Engl J Med. 2002;347(23):1876-1881.

7 CT Pulmonary Angiography Goldhaber SZ. N Engl J Med. 1998;339(2):93-104. Kearon SF. CMAJ. 2003;168:183-194.

8 Risk Factors: Virchow’s Triad Stasis –Immobility –Congestive heart failure Injury –Surgery (especially major orthopedic and pelvic) –Trauma Thrombophilia –Cancer –Oral contraceptives –Hereditary states (factor V Leiden, PT mutations)

9 VTE Epidemiology Most common cause of preventable death in hospitalized patients Risk of fatal perioperative PE ~0.8% International Multicentre Trial. Lancet. 1975 150,000 to 200,000 deaths per year; ~1/3 in perioperative patients Horlander et al. Arch Intern Med. 2003;163:1711-1717. AHRQ: VTE prevention is number 1 priority to improve safety in hospitals

10 Many Surgical Patients At-Risk 2003 Nationwide Inpatient Sample Adult surgical patients, LOS ≥2 days 7.8 million surgical discharges 44% low risk 15% moderate risk 24% high risk 17% very high risk 4.4 million at risk for VTE Anderson et al. Am J Hematol. 2007;82:777-782.

11 Million Women Study Population-based, prospective cohort study 947,454 middle-aged women in U.K. enrolled between 1996-2001 Mean follow-up 6.2 years 239,614 underwent surgery –5,419 readmitted for VTE within 12 weeks of inpatient surgery –270 deaths from fatal PE Sweetland et al. BMJ. 2009;339:b4583.

12

13 VTE Consequences Leg swelling, discomfort (DVT) Dyspnea, chest pain, hemoptysis, hypoxemia (PE) Extended hospital LOS Fatal PE (RV failure) ≥3 months of anticoagulant treatment Postphlebitic syndrome Chronic thromboembolic pulmonary HTN (~4%) Pengo et al. N Engl J Med. 2004;350:2257-2264.

14 VTE Prevention Targets one or two legs of Virchow’s triad: –Mechanical prophylaxis (stasis) Elastic compression stockings Intermittent pneumatic compression devices

15 VTE Prevention Targets one or two legs of Virchow’s triad: –Mechanical prophylaxis (stasis) Elastic compression stockings Intermittent pneumatic compression devices –Pharmacological prophylaxis (hypercoagulability) Unfractionated heparin Low-molecular-weight heparins Fondaparinux Aspirin (?)

16 Guidelines Defined “Systematically developed statements to assist practitioners and patient decisions about appropriate health care for specific circumstances.” Field MJ, Lohr KN (eds). Clinical Practice Guidelines: Directions for a New Program. Institute of Medicine, Washington, DC: National Academy Press, 1990.

17 Guidelines and Performance Measures Public reporting –Cardiac surgery outcomes in New York State Pay for performance –Reward “good” behavior –CMS: several VTE prevention P4P measures Registries –Accreditation –Facilitate quality improvement

18 Case Scenario 50 year-old woman scheduled to undergo elective laparoscopic cholecystectomy –PMH notable for moderate emphysema –No personal or family history of VTE –Medications: Spiriva®, albuterol –Stopped smoking 1 year ago What should we recommend for perioperative VTE prophylaxis in this patient?

19 BMJ. 1999;318:593-596.

20 Conceptual Framework VTE pharmacoprophylaxis involves a tradeoff between preventing thrombosis and causing bleeding When making tradeoffs, need to compare absolute risks of thrombosis and bleeding In order to determine absolute risks (eg, number of symptomatic DVTs prevented), need to know the following: –Baseline risk in control/comparison group –Relative risk for intervention vs control When making tradeoffs, also need to assign values to events being compared

21 ScenarioBaseline Risk of sVTE (%) Baseline Risk of Major Bleeding (%) RR VTE (UFH vs no Prophy) RR Bleed (UFH vs no Prophy) Number of VTEs Prevented (per 1000) Number of Bleeds Caused (per 1000) Any surgical patient ??0.502.0?? Calculating Absolute Effects

22 ScenarioBaseline Risk of sVTE (%) Baseline Risk of Major Bleeding (%) RR VTE (UFH vs no Prophy) RR Bleed (UFH vs no Prophy) Number of VTEs Prevented (per 1000) Number of Bleeds Caused (per 1000) Moderate VTE/ Average Bleed 21 0.502.0 10 Moderate VTE/ High bleed 221020 High VTE/ average bleed 412010 High VTE/ high bleed 4220 Calculating Absolute Effects

23 PICO Question Among patients undergoing elective abdominal surgery, should LDUH vs no prophylaxis be used for VTE prevention? Are we confident that the benefits of reducing fatal and nonfatal VTE exceed the harms of increasing fatal and nonfatal major bleeding?

24 Evidence Synthesis Systematic Review for each PICO! –Literature search –Assessment for eligibility –Assessment of study quality –Data abstraction and synthesis Expensive, time-consuming, and labor-intensive –AHRQ Evidence-Based Practice Centers

25 Assessment of Baseline Risk Ideal study Large, population-based Prospective (?) Few exclusions or losses to follow-up Well-defined endpoints –Important to patients –Objectively confirmed Sufficiently long time horizon No prophylaxis or controlled for prophylaxis Most studies Single center Referral center bias Prospective Employ surveillance methods to identify asymptomatic DVT Short time horizon No description or adjustment for prophylaxis

26 Ann Surg. 2010;251:344-350. Estimating Baseline Risk

27 Retrospective, observational study Large sample (n=8,216) of consecutively admitted “general” surgical inpatients Tertiary center Measured clinically suspected, objectively confirmed VTE over 30 days Risk stratification according to patient-specific and procedure-specific characteristics Prophylaxis nonuniform but reported

28 Baseline Risk of VTE

29 Case Scenario 50-year-old woman scheduled to undergo elective laparoscopic cholecystectomy –PMH notable for moderate COPD –No personal or family history of VTE –Medications: Spiriva®, albuterol –Stopped smoking 1 year ago What should we recommend for perioperative VTE prophylaxis in this patient?

30 Baseline Risk of VTE 4

31 Bahl et al. Ann Surg. 2010;251:344-350.

32 Baseline Risk of VTE Bahl et al. Ann Surg. 2010;251:344-350. 0.1%10%37% 52%

33 Prophylaxis Received Risk Category % Receiving Prophylaxis PharmMechanicalBothNeither Very low 00.550.080.37 Low 0.020.660.130.19 Moderate 0.050.550.210.2 High 0.050.520.270.16 All 0.050.550.230.18

34 VTE Risk Patient Population Risk categories from AT7 Patients undergoing general surgery, including gastrointestinal, urological, vascular, breast and thyroid procedures Estimated risk (%) Proximal DVT PECaprini score Observed risk of sVTE (%) Adjusted risk of sVTE (%) Very low 0.40.2000 Low2-41-2 0.71.7 Mod4-82-43-41.02.6 High>104-10≥51.95.7

35 Estimated Baseline Risk Caprini score = 4 Unadjusted risk = 1.0% Crude adjusted risk = 2.6% Observed, unadjusted risk in observational study of 2,274 discharges following lap chole in California, 1992-1996 was 0.9% White RH et al. Thromb Haemost. 2003;90:446-455.

36 ScenarioBaseline Risk of sVTE (%) Baseline Risk of Major Bleeding (%) RR VTE (UFH vs no Prophy) RR Bleed (UFH vs no Prophy) Number of VTEs Prevented (per 1000) Number of Bleeds Caused (per 1000) Moderate VTE- risk patient 2.61.2???? Calculating Absolute Effects

37 Assessment of Safety/Effectiveness Ideal study Large, multicenter RCT Blinding of patients, treating physicians, adjudicators Well-defined endpoints –Important to patients –Objectively confirmed Few exclusions or losses to follow-up Sufficiently long time horizon Most studies Small, single center Referral center bias Incomplete blinding Surrogate outcome, asymptomatic DVT Large percent excluded from efficacy evaluation Short time horizon

38 Effectiveness of LDUH: IMT

39 IMT Design Unblinded, randomized, controlled trial Patients: adults age > 40 years undergoing major elective surgery (GA, >30 min, LOS ≥ 7 days) at 28 centers in Europe, Australia and South Africa Intervention: UFH 5,000 units tid for 7 days, 1st dose 2 hours pre-op Comparator: no prophylaxis Outcomes: fatal PE, fatal bleed, nonfatal PE, nonfatal bleed, clinical DVT, DVT by FUT

40 IMT Outcomes PE: clinically suspected with confirmatory evidence recorded (chest radioraph and ECG) Fatal PE: confirmed by autopsy DVT: –Clinically suspected and confirmed by venography –Continuous surveillance by fibrinogen uptake test (10 centers) Excessive operative bleeding (surgeon’s judgment) Wound hematoma, transfusion, fall in Hgb

41 IMT Results: VTE OutcomeLDUH N=2045 No Prophylaxis N=2076 RR Death any cause801000.81 (0.61 to 1.1) Fatal PE2160.13 (0.02 to 0.55) Death with PE360.51 (0.13 to 2.0) Suspected DVT39810.49 (0.33 to 0.71) Confirmed DVT11320.35 (0.18 to 0.69) DVT by FUT48/625164/6670.31 (0.23 to 0.42) Proximal DVT5/62549/6670.11 (0.04 to 0.27)

42 IMT Results: Bleeding OutcomeLDUH N=2045 No Prophylaxis N=2076 RR Fatal bleed450.81 (0.21 to 3.0) Excessive intra-op1821261.47 (1.18 to 1.82) Wound hematoma1581171.37 (1.09 to 1.73) Transfusion202/731202/7441.02 (0.86 to 1.20)

43 Collins Meta-analysis N Engl J Med. 1988;318:1162-1173.

44 Collins Meta-analysis 69 studies of LDUH prophylaxis –General surgery (45) –Urology (7) –Elective orthopedic (12) –Trauma (7) About half open label Most measured surrogate outcome for VTE Many used suboptimal test (FUT) Bleeding outcome: excessive intraoperative bleeding or need from transfusion

45 Results: Meta-analysis OutcomeStudies With at Least 1 Event Baseline Risk in Control Groups Pooled OR (REM) Death from any cause323.5%0.82 (0.69 to 0.99) Fatal PE200.8%0.53 (0.31 to 0.91) Nonfatal PE322.1%0.59 (0.41 to 0.84) Fatal bleeding70.1%1.14 (0.41 to 3.15) Nonfatal bleeding443.8%1.57 (1.32 to 1.87)

46 Sensitivity Analysis Frequency –Q8h  72 +/- 5 –Q12h  63 +/-5

47 ScenarioBaseline Risk of sVTE (%) Baseline Risk of Major Bleeding (%) RR VTE (UFH vs no Prophy) RR Bleed (UFH vs no Prophy) Number of VTEs Prevented (per 1000) Number of Bleeds Caused (per 1000) Moderate VTE-Risk Patient 2.61.20.591.57117 Calculating Absolute Effects

48 Evidence Synthesis: Tradeoffs between desirable and undesirable outcomes

49 Summary of Findings Importance Absolute RisksEffect LDUHNo Prophylaxis Relative (95% CI) Absolute Nonfatal symptomatic VTE, inferred from no-fatal PE (clinical diagnosis) 118/8216 (1.4%) 1.7% OR 0.59 (0.41 to 0.84) 7 fewer per 1000 CRITICAL 2.6%11 fewer per 1000 5.7%23 fewer per 1000 Non-fatal major bleeding, inferred from excessive intraoperative bleeding or need for transfusion (clinical diagnosis) 388/6524 (5.9%) 1.2% OR 1.57 (1.32 to 1.87) 7 more per 1000 CRITICAL 2.2%12 more per 1000

50 Summary of Findings Importance Absolute RisksEffect LDUHNo Prophylaxis Relative (95% CI) Absolute Fatal PE (autopsy) 19/6809 (0.3%) 0.3% OR 0.53 (0.31 to 0.91) 1 fewer per 1000 CRITICAL 0.5%2 fewer per 1000 1.1%5 fewer per 1000 Fatal bleeding (autopsy) 7/6703 (0.1%) 0.09% OR 1.14 (0.41 to 3.15) 0 more per 1000 CRITICAL 0.17%0 more per 1000

51 GRADE: Quality of Evidence LimitationsInconsistencyIndirectnessImprecisionOther Threats to validity, risk of bias: concealment of allocation sequence, blinding, losses to follow-up, selective reporting, early stopping Unexplained heterogeneity in results across studies Indirect evidence from different population, intervention, comparator or outcome OR Indirect comparison: Use studies of A vs B and B vs C to compare A vs C Confidence interval around effect includes both no effect and either important benefit or important harm (or both) Potential for publication bias

52 Quality Assessment No. of StudiesDesignLimitationsInconsistencyIndirectnessImprecisionQuality Fatal PE 20 randomised trials no serious limitations +/- no serious indirectness no serious imprecision Moderate to High Fatal bleeding 7 randomised trials no serious limitations no serious inconsistency no serious indirectness seriousModerate No-fatal symptomatic VTE, inferred from nonfatal PE 32 randomised trials seriousmild no serious indirectness no serious imprecision Moderate Nonfatal major bleeding, inferred from excessive intraoperative bleeding or need for transfusion 44randomised trials seriousno serious inconsistency no serious indirectness no serious imprecision Moderate

53 Guyatt et al. BMJ. 2008;336:1049-1051.

54 GRADE: Strength of Recommendation BMJ. 2008;336:1049-1051.

55 Recommendation For general surgical patients at moderate risk for venous thromboembolism who are not at high risk for perioperative bleeding, we suggest low-dose unfractionated heparin (Grade 2B) over no prophylaxis.

56 Recommendation For general surgical patients at high risk for venous thromboembolism who are not at high risk for perioperative bleeding, we recommend use of low-dose unfractionated heparin (Grade 1B) over no prophylaxis.

57 Major Challenges Multiple sources of heterogeneity Indirectness –When should one apply indirect evidence from studies performed in a mixed (surgical) or different patient population? Surrogate outcome: asymptomatic DVT Poorly standardized outcome: major bleeding Limited information about baseline risk of VTE in absence of prophylaxis

58 Biases Introduced by Surveillance for Asymptomatic DVT Downward: identification and treatment of asymptomatic DVT prevents unknown number of events that would have become symptomatic Upward: more likely to label a finding (eg, leg swelling) as a symptomatic if event is detected by surveillance Difficult to estimate the ratio of asymptomatic to symptomatic events

59 Additional Challenges Numerous comparisons –LDUH, LMWH, fondaparinux, low-dose ASA, high-dose ASA, ES and IPC vs no prophy –Mechanical vs pharmacologic –Add mechanical to pharmacologic –16 unique evidence profiles and still counting! Numerous surgical populations –Abdomen and pelvis (vascular, bariatric) –Neurosurgery (craniotomy, spine) –Trauma (TBI, SCI, other major trauma) –Cardiac, thoracic, other…

60 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at very low risk for VTE (< 0.5%; Rogers score, < 7; Caprini score, 0), we recommend that no specific pharmacologic (Grade 1B) or mechanical (Grade 2C) prophylaxis be used other than early ambulation.

61 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at low risk for VTE (~ 1.5%; Rogers score, 7-10; Caprini score, 1-2), we suggest mechanical prophylaxis, preferably with intermittent pneumatic compression (IPC), over no prophylaxis (Grade 2C).

62 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at moderate risk for VTE (~ 3.0%; Rogers score, > 10; Caprini score, 3-4) who are not at high risk for major bleeding complications, we suggest LMWH (Grade 2B), LDUH (Grade 2B), or mechanical prophylaxis, preferably with IPC (Grade 2C), over no prophylaxis. Remarks: Three of the seven authors favored a strong (Grade 1B) recommendation in favor of LMWH or LDUH over no prophylaxis in this group.

63 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at moderate risk for VTE (3.0%; Rogers score, > 10; Caprini score, 3-4) who are at high risk for major bleeding complications or those in whom the consequences of bleeding are thought to be particularly severe, we suggest mechanical prophylaxis, preferably with IPC, over no prophylaxis (Grade 2C).

64 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at high risk for VTE (~ 6.0%; Caprini score, ≥ 5) who are not at high risk for major bleeding complications, we recommend pharmacologic prophylaxis with LMWH (Grade 1B) or LDUH (Grade 1B) over no prophylaxis. We suggest that mechanical prophylaxis with elastic stockings or IPC should be added to pharmacologic prophylaxis (Grade 2C).

65 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For high-VTE-risk patients undergoing abdominal or pelvic surgery for cancer who are not otherwise at high risk for major bleeding complications, we recommend extended-duration pharmacologic prophylaxis (4 weeks) with LMWH over limited-duration prophylaxis (Grade 1B). Remarks: Patients who place a high value on minimizing out-of- pocket health-care costs might prefer limited-duration over extended-duration prophylaxis in settings where the cost of extended-duration prophylaxis is borne by the patient.

66 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For high-VTE-risk general and abdominal-pelvic surgery patients who are at high risk for major bleeding complications or those in whom the consequences of bleeding are thought to be particularly severe, we suggest use of mechanical prophylaxis, preferably with IPC, over no prophylaxis until the risk of bleeding diminishes and pharmacologic prophylaxis may be initiated (Grade 2C).

67 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients at high risk for VTE (6%; Caprini score, ≥ 5) in whom both LMWH and unfractionated heparin are contraindicated or unavailable and who are not at high risk for major bleeding complications, we suggest low-dose aspirin (Grade 2C), fondaparinux (Grade 2C), or mechanical prophylaxis, preferably with IPC (Grade 2C), over no prophylaxis.

68 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients, we suggest that an inferior vena cava (IVC) filter should not be used for primary VTE prevention (Grade 2C).

69 Patients Undergoing General, GI, Urologic, Gynecologic, Bariatric, Vascular, Plastic, or Reconstructive Surgery For general and abdominal-pelvic surgery patients, we suggest that periodic surveillance with venous compression ultrasound (VCU) should not be performed (Grade 2C).

70 Patients Undergoing Cardiac Surgery For cardiac surgery patients with an uncomplicated postoperative course, we suggest use of mechanical prophylaxis, preferably with optimally applied IPC, over either no prophylaxis (Grade 2C) or pharmacologic prophylaxis (Grade 2C).

71 Patients Undergoing Cardiac Surgery For cardiac surgery patients whose hospital course is prolonged by one or more nonhemorrhagic surgical complications, we suggest adding pharmacologic prophylaxis with LDUH or LMWH to mechanical prophylaxis (Grade 2C).

72 Patients Undergoing Thoracic Surgery For thoracic surgery patients at moderate risk for VTE who are not at high risk for perioperative bleeding, we suggest LDUH (Grade 2B), LMWH (Grade 2B), or mechanical prophylaxis with optimally applied IPC (Grade 2C) over no prophylaxis. Remarks: Three of the seven authors favored a strong (Grade 1B) recommendation in favor of LMWH or LDUH over no prophylaxis in this group.

73 Patients Undergoing Thoracic Surgery For thoracic surgery patients at high risk for VTE who are not at high risk for perioperative bleeding, we suggest LDUH (Grade 1B) or LMWH (Grade 1B) over no prophylaxis. In addition, we suggest that mechanical prophylaxis with ES or IPC should be added to pharmacologic prophylaxis (Grade 2C).

74 Patients Undergoing Thoracic Surgery For thoracic surgery patients who are at high risk for major bleeding, we suggest use of mechanical prophylaxis, preferably with optimally applied IPC, over no prophylaxis until the risk of bleeding diminishes and pharmacologic prophylaxis may be initiated (Grade 2C).

75 Patients Undergoing Craniotomy For craniotomy patients, we suggest that mechanical prophylaxis, preferably with IPC, be used over no prophylaxis (Grade 2C) or pharmacologic prophylaxis (Grade 2C).

76 Patients Undergoing Craniotomy For craniotomy patients at very high risk for VTE (eg, those undergoing craniotomy for malignant disease), we suggest adding pharmacologic prophylaxis to mechanical prophylaxis once adequate hemostasis is established and the risk of bleeding decreases (Grade 2C).

77 Patients Undergoing Spinal Surgery For patients undergoing spinal surgery, we suggest mechanical prophylaxis, preferably with IPC, over no prophylaxis (Grade 2C), unfractionated heparin (Grade 2C), or LMWH (Grade 2C).

78 Patients Undergoing Spinal Surgery For patients undergoing spinal surgery at high risk for VTE (including those with malignant disease or those undergoing surgery with a combined anterior-posterior approach), we suggest adding pharmacologic prophylaxis to mechanical prophylaxis once adequate hemostasis is established and the risk of bleeding decreases (Grade 2C).

79 Major Trauma For major trauma patients, we suggest use of LDUH (Grade 2C), LMWH (Grade 2C), or mechanical prophylaxis, preferably with IPC (Grade 2C), over no prophylaxis.

80 Major Trauma For major trauma patients in whom LMWH and LDUH are contraindicated, we suggest mechanical prophylaxis, preferably with IPC, over no prophylaxis (Grade 2C) when not contraindicated by lower-extremity injury. We suggest adding pharmacologic prophylaxis with either LMWH or LDUH when the risk of bleeding diminishes or the contraindication to heparin resolves (Grade 2C).

81 Major Trauma For major trauma patients, we suggest that an IVC filter should not be used for primary VTE prevention (Grade 2C).

82 Patients With Major Trauma: Traumatic Brain Injury, Acute Spinal Injury, and Traumatic Spine Injury For major trauma patients at high risk for VTE (including those with acute spinal cord injury, traumatic brain injury, and spinal surgery for trauma), we suggest adding mechanical prophylaxis to pharmacologic prophylaxis (Grade 2C) when not contraindicated by lower extremity injury.

83 Patients With Major Trauma: Traumatic Brain Injury, Acute Spinal Injury, and Traumatic Spine Injury For major trauma patients, we suggest that periodic surveillance with VCU should not be performed (Grade 2C).

84 Endorsing Organizations This guideline has received the endorsement of the following organizations: American Association for Clinical Chemistry American College of Clinical Pharmacy American Society of Health-System Pharmacists American Society of Hematology International Society of Thrombosis and Hemostasis

85 Acknowledgement of Support The ACCP appreciates the support of the following organizations for some part of the guideline development process: Bayer Schering Pharma AG National Heart, Lung, and Blood Institute ( Grant No.R13 HL104758) With educational grants from Bristol-Myers Squibb and Pfizer, Inc. Canyon Pharmaceuticals, and sanofi-aventis U.S. Although these organizations supported some portion of the development of the guidelines, they did not participate in any manner with the scope, panel selection, evidence review, development, manuscript writing, recommendation drafting or grading, voting, or review. Supporters did not see the guidelines until they were published.


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