Year : 2012 | Volume
: 5 | Issue : 2 | Page : 118--119
Risk-benefit decision making in traumatic brain injury: Ratios, realities, results
Chee M Chan1, Marya D Zilberberg2,
1 Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington Hospital Center, Washington, DC, USA
2 School of Public Health and Health Sciences, University of Massachusetts, Amherst and EviMed Research Group, LLC, Goshen, MA, USA
Chee M Chan
Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington Hospital Center, Washington, DC
|How to cite this article:|
Chan CM, Zilberberg MD. Risk-benefit decision making in traumatic brain injury: Ratios, realities, results.J Emerg Trauma Shock 2012;5:118-119
|How to cite this URL:|
Chan CM, Zilberberg MD. Risk-benefit decision making in traumatic brain injury: Ratios, realities, results. J Emerg Trauma Shock [serial online] 2012 [cited 2020 Jul 15 ];5:118-119
Available from: http://www.onlinejets.org/text.asp?2012/5/2/118/96478
Traumatic brain injury (TBI) often results in devastating neurologic consequences while simultaneously increasing the risk for multiple, severe complications. Among all these potential adverse sequelae, venous thromboembolism (VTE) represents one of the most dreaded complications. , Fortunately, multiple preventive options exist for VTE and range from injectable anticoagulants to compression devices.  However, physicians must consider both the choice of and initiation of thrombophylaxis in TBI patients carefully. The use of an anticoagulant in this patient population may precipitate intracranial bleeding, while failure to initiate appropriate VTE prophylaxis may result in either a fatal pulmonary embolus (PE) or some other VTE that requires full strength anticoagulation and its attendant risks. Few clinical trials exist to guide clinicians in deciding timing, appropriate dosage, and duration of VTE prophylaxis in TBI patients. Thus, physicians are left with weighing the risk:benefit ratio of chemical VTE prophylaxis in the setting of potentiating intracranial bleeding vs. allowing a deadly PE to develop. Therefore, there is an urgent need for data that elucidate the true incidence of VTE and the safety and efficacy of thromboprophylaxis in the isolated TBI.
In this issue of the Journal of Emergencies, Trauma, and Shock, Mohseni and colleagues  attempt to address these issues and demonstrate the difficulty in answering these questions for this unique population. In a retrospective matched case control study, the authors conclude that VTE rates are higher in those who do not receive anticoagulation and that VTE prophylaxis appears safe to administer. They also found that both hospital and intensive care unit length of stay are similar between groups. Hence, the authors conclude that prophylactic anticoagulation decreases the overall risk for clinically significant VTE in patients who have suffered severe isolated TBI.
While the authors make a good faith effort at grappling with these issues, there are several flaws in their methodology and their interpretation of the data. From an epidemiologic standpoint, a case control study cannot determine the true incidence of disease. Since selected cases are matched with controls, the relative risk can only be estimated from a calculated odds ratio. Thus, the current study design is inappropriate for their primary question. Further, there is substantial confounding by indication. Patients with TBI were initiated on VTE prophylaxis at the discretion and recommendation of the neurosurgical team. As such, the prescription of thromboprophylaxis may simply reflect the better overall prognosis of these patients because the surgeons felt that the patients would survive long enough to be at risk for a VTE. This possibility is also illustrated in the mortality rates and in Table 3 of their manuscript where causes of death are enumerated. The majority of patients who died and did not receive thromboprophylaxis had care withdrawn compared to those who received VTE prophylaxis (where these individuals died from progressive organ failure). This finding may actually represent the aggressiveness of end of life discussions in patients with poorer predicted outcomes. Also, although more patients were noted to die in the group that did not receive anticoagulants, many factors potentially affect mortality rates. Not only can the development of VTE alter mortality, but so can comorbid conditions, family and patient wishes regarding end of life care, and health care acquired infections. Mohseni et al. fail to consider any of these potential confounders. The fact that mortality rates were different between the treated and untreated cohorts may only further demonstrate the disparities in prognosis between the two groups. To combat the possibility of confounding by indication, propensity scoring was used matching for age, gender, and severity of illness. However, it is impossible to match every possible variable that could affect outcome, particularly with such a small sample size.
Prior evidence has demonstrated that earlier use of VTE prophylaxis may be effective and safe in TBI subjects. In another retrospective cohort study consisting of 699 hemodynamically stable TBI patients, the rate of bleeding was compared between those who received thromboprophylaxis within the first 72 hours vs those who received it late (>72 hours).  These authors found that the rate of bleeding was similar between groups (1.49 vs. 1.54, P>0.90). Therefore, one must wonder if the administration of VTE prophylaxis so late in this study (mean: 10 days) is actually protective. Contrarily, those who developed VTE may have done so for other reasons (e.g., central line placement and malignancy). Finally, the extremely small sample size of this study makes it difficult to compare clinically significant VTE and bleeding rates between the two groups. Although it is well documented that trauma patients are at higher risk of developing VTE, many of these VTEs are clinically silent. For example, Geerts et al. found that screening ultrasonography will diagnose a deep venous thrombus in approximately 60% of trauma patients; however, of these, only 1.5% are actually symptomatic.  A much larger sample size would therefore be necessary to determine whether VTE prophylaxis is safe and efficacious.
The questions posed in this article are extremely important. Given the heightened potential risk for morbidity and mortality on both sides of this equation, research must be prioritized to help clinicians safely administer thromboprophylaxis while maximizing efficacy. At the very least, this study increases awareness of the paucity of data surrounding this topic and is a first step toward designing the next study.
This commentary was written on the article:
Venous thromboembolic events in isolated severe traumatic brain injury: A matched case control study.
Mohseni S, Talving P, Lam L, Chan LS, Ives C, Demetriades D. Venous thromboembolic events in isolated severe traumatic brain injury. J Emerg Trauma Shock 2012;5:11-5.
|1||Nathens AB, McMurray MK, Cuschieri J, Durr EA, Moore EE, Bankey PE, et al. The practice of venous thromboembolism prophylaxis in the major trauma patient. J Trauma 2007;62:557-63.|
|2||Rogers FB, Cipolle MD, Velmahos G, Rozycki G, Luchette FA. Practice management guidelines for the prevention of venous thromboembolism in trauma patients: The EAST practice management guidelines work group. J Trauma 2002;53:142-64.|
|3||Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, et al. Prevention of venous thromboembolism: American College of chest physicians evidence-based clinical practice guidelines (8 th Edition). Chest 2008;133 (6 Suppl):381S-453S.|
|4||Mohseni S, Talving P, Lam L, Chan LS, Ives C, Demetriades D. Venous thromboembolic events in isolated severe traumatic brain injury: A matched case control study. J Emerg Trauma Shock 2012;5:11-5.|
|5||Koehler DM, Shipman J, Davidson MA, Guillamondegui O. Is early venous thromboembolism prophylaxis safe in trauma patients with intracranial hemorrhage. J Trauma 2011;70:324-9.|
|6||Geerts WH, Code KI, Jay RM, Chen E, Szalai JP. A prospective study of venous thromboembolism after major trauma. N Engl J Med 1994;331:1601-6.|