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Yngve Falck-Ytter, MD; Clive Kearon, MD; Elie Akl, MD; Charles Francis, MD
Author and Funding Information

From the Case Western Reserve University (Dr Falck-Ytter), School of Medicine, Department of Medicine, Case and VA Medical Center; Departments of Medicine and Clinical Epidemiology and Biostatistics (Dr Kearon), Michael De Groote School of Medicine, McMaster University; State University of New York at Buffalo (Dr Akl); Department of Internal Medicine, (Dr Akl), American University of Beirut; and University of Rochester Medical Center (Dr Francis), Hematology/Oncology Unit.

Correspondence to: Yngve Falck-Ytter, MD, Case Western Reserve University School of Medicine, Department of Medicine, Case and VA Medical Center, 10701 E Blvd, Cleveland, OH, 44106; e-mail: yngve.falck-ytter@case.edu


Financial/nonfinancial disclosures: The authors of this guideline provided detailed conflict of interest information related to each individual recommendation made in this article. A grid of these disclosures is available online at http://chestjournal.chestpubs.org/content/141/2_suppl/e278S/suppl/DC1. Dr Kearon is a con­sultant to Boehringer Ingelheim and has received peer-reviewed funding for studies in the treatment of VTE. Dr Akl is a member of and prominent contributor to the GRADE Working Group. Dr Francis received research grant support from the National Heart, Lung, and Blood Institute and Eisai Co, Ltd, and served as a steering committee member for a clinical trial sponsored by Eisai Co, Ltd. Dr Falck-Ytter has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(3):874-875. doi:10.1378/chest.12-2717
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To the Editor:

We thank Drs Llinas and Cardenas for the opportunity to clarify the distinction between the methodologic issue of using asymptomatic VTE to estimate relative effects and the clinical issue of considering asymptomatic VTE as a patient condition requiring management. From the methodologic perspective, the three prevention chapters of the ninth edition of the American College of Chest Physicians Antithrombotic Guidelines (AT9) did not “exclude from consideration asymptomatic DVT.”1-3 We considered both symptomatic and asymptomatic venous thrombotic events reported in trials to estimate relative effects of interventions. However, asymptomatic VTE was viewed as a surrogate for symptomatic VTE and we extensively evaluated different strategies on how to conceptually link such surrogate measures to clinically relevant outcomes.4

In short, when a meaningful number of symptomatic VTEs were available, we based our estimate of effect of an intervention on those patient-important outcomes. When only asymptomatic events from venography were reported, we used the relative effect estimates from those asymptomatic events, but applied this relative effect measure to our best estimate of baseline risk for symptomatic thrombotic events postoperatively. We rated down the quality of the evidence for those outcomes due to indirectness (surrogate outcome).

From the clinical perspective, we recommended strongly against screening asymptomatic patients for VTE with Doppler ultrasound after any orthopedic surgery to avoid detecting incidental DVTs, as moderate-quality evidence showed that harm of subsequent treatment outweighed any potential benefit.3 Consistent with this recommendation, the chapter by Kearon and colleagues5 on treatment of VTE does not comment on treatment of asymptomatic DVT detected by screening venography after surgery. That chapter does, however, provide recommendations for treatment of asymptomatic DVT and pulmonary embolism incidentally detected by imaging studies performed for other reasons (eg, CT scanning for staging of cancer).5 When these are DVTs, they are usually large intraabdominal thrombi, and not small thrombi that are confined to the distal deep veins of the leg.5

References

Kahn SR, Lim W, Dunn AS, et al. Prevention of VTE in nonsurgical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e195S-e226S. [CrossRef] [PubMed]
 
Gould MK, Garcia DA, Wren SM, et al. Prevention of VTE in nonorthopedic surgical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e227S-e277S. [CrossRef] [PubMed]
 
Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e278S-e325S. [CrossRef] [PubMed]
 
Guyatt GH, Eikelboom JW, Gould MK, et al. Approach to outcome measurement in the prevention of thrombosis in surgical and medical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e185S-e194S. [CrossRef] [PubMed]
 
Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e419S-e494S. [CrossRef] [PubMed]
 

Figures

Tables

References

Kahn SR, Lim W, Dunn AS, et al. Prevention of VTE in nonsurgical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e195S-e226S. [CrossRef] [PubMed]
 
Gould MK, Garcia DA, Wren SM, et al. Prevention of VTE in nonorthopedic surgical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e227S-e277S. [CrossRef] [PubMed]
 
Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e278S-e325S. [CrossRef] [PubMed]
 
Guyatt GH, Eikelboom JW, Gould MK, et al. Approach to outcome measurement in the prevention of thrombosis in surgical and medical patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e185S-e194S. [CrossRef] [PubMed]
 
Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):e419S-e494S. [CrossRef] [PubMed]
 
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