To the Editor:
Venous thromboembolism (VTE) is the third most common cause of vascular mortality worldwide and comprises deep-vein thrombosis and pulmonary embolism and is preventable.1-3 Implementation of VTE guidelines emerging from randomized trials is one of the most effective health-care interventions arising in the 20th century.1-3 Although mundane in approach, VTE prophylaxis has a huge influence on mortality. It is of utmost importance to all hospitalized patients, particularly those experiencing hemiparesis from neurological injury.
In the May 2020 issue of Neurosurgery, Dr Haine's4 “Commentary: What We Might or Might Not Know About Venous Thromboembolism Prophylaxis in Neurosurgery” reviewed and expanded on the methodology incorporated into the Neurocritical Care Society guidelines on VTE prophylaxis in patients with craniotomies. We authored the following recommendations from the section “Recommendations for Prevention of VTE in Elective Craniotomy” of the Neurocritical Care Society's guideline.5 We recommend using intermittent pneumatic compression with either low molecular weight heparin or unfrationated heparin within 24 h after a craniotomy (strong recommendation and moderate-quality evidence).
Dr Haines has completed a comprehensive and detailed review of the literature, significantly adding to, and expanding the understanding of the topic. He has made several important observations and outlines the dilemmas facing us when we constructed these guidelines. These include issues such as the fact that most studies were done in the almost distant past and incorporate study designs not meeting the current definition of Level 1 evidence. Most of the craniotomy associated literature are single-center extended case series often incorporating mixed craniotomy phenotypes. They combine endpoints such as traumatic brain injury with mixed tumor types, all with very different underlying risk for VTE. These observations make the case for the need for larger studies with more power and better design.
The Neurocritical Care Society set out to develop an evidence-based guideline using grading of recommendations, assessment, development, and evaluations (GRADE) to safely reduce VTE and its associated complications. When formulating the present guideline, it was our goal to act as a resource that would function as a synopsis of the best clinical data available as a starting point for future clinical trials. The GRADE system allows for the use of inference from clinical experts to develop guidelines in the absence of the highest quality clinical trials. This is required in the setting of rare neurological diseases in which no comprehensive recommendations on this topic exist prior to these guideline and studies meeting the modern standards of Level 1 evidence are rare.
Guidelines are only recommendations and the local physician operating in his specific clinical niche should not be required to view these recommendations as a specific statement on the standard of care in their institution. The present guidelines are meant to be the starting point from which we should design future trials to address the ascertainment of risk associated with VTE. Without Level 1 evidence in the form of modern randomized clinical trials, the clinical reasoning associated with the use or nonuse of VTE prophylaxis often falls into one of three common patterns of fallacious reasoning: (1) appeal to authority, (2) using the extreme to define the norm, and (3) using association to infer causation. A suitable sample size is needed to execute an appropriately powered and well-designed study examining the use of appropriate VTE prophylaxis in elective craniotomies. We as a community would need to recruit a high percentage of the desired postcraniotomy cases occurring annually in the United States and probably extend this study to centers outside the United States or conduct a study over a very long period.
In the 21st century, center for medicare and medical services (CMS) is becoming a major influencer of reimbursement and clinical practice in neurosurgery, determining what clinical care will be funded based on supporting Level 1 clinical evidence. Standard VTE is a focus of that influence and directly influenced through the reimbursement policies dictated by CMS. Without adequate Level 1 data, the present data could significantly compromise the number of effective therapies available to our patients. This situation demonstrates the need to develop clinical collaborations between the American Congress of Neurosurgeons and organizations such as the Neurocritical Care Society and Society of Critical Care Medicine to address this issue and complete studies meeting the standard of Level 1 evidence in VTE.
In 2012, the Congress of Neurological Surgeons, American Association of Neurological Surgeons (AANS), and Society of Neurological Surgeons identified 3689 practicing board certified neurosurgeons in the United States. Similarly, there were only 1280 certified neurocritical care physicians and 12,000 critical care physicians of all types.6 To complete such a study, the AANS does not have enough members to lead such an effort. To this end, I would strongly suggest the formation of a working group with members from all three societies above to develop a consensus statement addressing the next steps forward in the study of VTE and VTE prophylaxis of specialized neurological populations in the setting of critical care. They should define appropriate phenotypes, appropriate therapies, and a way forward to execute studies. We must strive to serve our specialized patients by banding together and leading the way to effective scientifically based care of VTE!
This study did not receive any funding or financial support.
The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.
1. Nicholson M, Chan N, Bhagirath V, Ginsberg J. Prevention of venous thromboembolism in 2020 and beyond. J Clin Med. 2020;9(8):2467.
2. Wendelboe AM, Raskob GE. Global burden of thrombosis: epidemiologic aspects. Circ Res. 2016;118(9):1340-1347.
3. Lilly CM, Liu X, Badawi O, Franey CS, Zuckerman IH. Thrombosis prophylaxis and mortality risk among critically ill adults. Chest. 2014;146(1):51-57.
4. Haines SJ. Commentary: what we might or might not know about venous thromboembolism prophylaxis in neurosurgery. Neurosurgery. 2020;86(5):E455-E468.
5. Nyquist P, Bautista C, Jichici D, et al. Prophylaxis of venous thrombosis in neurocritical care patients: an evidence-based guideline: a statement for healthcare professionals from the neurocritical care society. Neurocrit Care. 2016;24(1):47-60.
6. Halpern NA, Pastores SM, Oropello JM, Kvetan V. Critical care medicine in the United States: addressing the intensivist shortage and image of the specialty. Crit Care Med. 2013;41(12):2754-2761.