Why Thrombosis Prophylaxis Fails
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author affiliations:
From the Division of Vascular Surgery, NorthShore University Health System, Evanston, Illinois, Northwestern University Feinberg School of Medicine, Chicago, Illinois, and the Robert R. McCormick School of Bioengineering Northwestern University, Evanston, Illinois.
The author discloses no conflicts of interest regarding the content herein.
Manuscript submitted November 11, 2008, provisional acceptance given January 12, 2009, final version accepted January 30, 2009.
Address for correspondence: Joseph A. Caprini, MD, MS, FACS, Louis Biegler Professor of Surgery, Division of Vascular Surgery, NorthShore University Health System, Coventry Road, Northfield, IL 60093. E-mail: jcaprini2@aol.com
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Abstract
Thrombosis prophylaxis methods have been widely tested and found to be extremely effective for the prevention of serious or fatal events known to be common in patients undergoing surgery or who are medically ill. A common reason for failure occurs when physicians apply inadequate measures due to a lack of awareness of the problem. Failure to perform individual risk assessment is another common reason for failure, since individuals may undergo a low-risk operation but have multiple risk factors dictating a much more robust approach to prophylaxis than group recommendations dictate. The presence of ongoing risk such as cancer or history of past venous thromboembolism (VTE) may dictate the use of prophylaxis following hospital discharge. Failure to provide this coverage often leads to serious or fatal events days or even weeks later. The use of aspirin for prophylaxis after orthopedic surgery is a weak, relatively ineffective approach to preventing the many faces of VTE, including clinical and asymptomatic VTE, pulmonary hypertension, paradoxical stroke and the post-thrombotic syndrome. Finally, failure to use combination physical and pharmacologic methods together in the highest-risk patients may lead to the development of VTE, which could be avoided with an appropriate combination approach.
Background
Venous thromboembolism (VTE) is a serious and often fatal disease affecting approximately 900,000 individuals in the United States each year, according to Heit et al.1 They estimate that 296,000 deaths from pulmonary embolism (PE) occur, including 34% who present as sudden death. The inability of the clinician to help patients who die without warning is a frustrating problem. Many of these hospitalized patients had serious disease, and without an autopsy, often the true cause of death was never determined. One-third of these fatalities occurred following hospital discharge, which presents a difficult problem since resources are generally lacking for careful followup after discharge. It is uncommon to have autopsies performed in these individuals due to cost and other issues. Unfortunately, without accurate necropsy data, the true incidence of fatal PE or paradoxical stroke is difficult to determine. Heit et al developed an incidence-based model that included both hospital- and community-acquired VTE events, as well as death from recognized and unrecognized VTE.
A similar analysis of inpatients, using VTE criteria established by the American College of Chest Physicians (ACCP) estimated that more than 12 million patients are at risk for VTE.2 A total of 7.7 million medical in-patients and 4.3 million surgical patients met ACCP guideline criteria for VTE risk, with VTE prophylaxis recommended.2 Although the risk of deep vein thrombosis (DVT) is thought to be most commonly associated with surgical patients, 50–70% of symptomatic thromboembolic events and 70–80% of fatal PE occur in nonsurgical patients.3 Approximately 10% of all hospital deaths are due to PE. Patients in the medical intensive care unit (ICU) are at particularly high risk for DVT. During an 8-month screening study, DVT was detected by ultrasound in 33% of 100 patients admitted to the medical ICU with an anticipated minimum stay of 48 hours.4 It is unfortunate that these facts are not common knowledge among both physicians and the public.
Inadequate prophylaxis due to lack of awareness
Lack of awareness is a major reason for inappropriate or weak thromboprophylaxis use in many hospitalized patients. Failure of an inadequate thromboprophylaxis measure such as aspirin is one example and is not recommended by Chest or the International Consensus Guidelines.5,6 The American Academy of Orthopedic Surgeons created a position statement that endorses the use of aspirin in some orthopedic patients, but these changes lack robust evidence-based guidelines documents.7
Failure to perform individual risk assessment
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