Why are objective tests needed to diagnose venous thromboembolism (VTE)?
Which tests can be used to diagnose a first DVT?
Which tests can be used to diagnose recurrent DVT?
Which tests can be used to diagnose PE?
In 800 bc, Susruta, an Indian healer wrote about a patient with “a swollen and painful leg, which was difficult to treat.” Centuries later, Virchow, a Prussian physician, coined the term “embolism” after discovering the relationship between a blood clot that formed within a blood vessel (thrombus), and a blood clot that breaks loose from the original and travels through the bloodstream to occlude the pulmonary vessels (embolus). The concept of venous thromboembolism was born from these early descriptions and today it remains one of the most important health problems in Europe and North America and is the third leading cause of vascular death after myocardial infarction and stroke.
The risk of VTE increases by approximately twofold per decade of age, rising from an annual incidence of 30/100,000 at 40 years of age, to 90/100,000 at 60 years, and 260/100,000 at 80 years. Approximately half of patients with untreated, symptomatic proximal DVT will develop symptomatic PE, and about 10% of symptomatic PE incidents are fatal within an hour of onset. Left untreated, one-third of patients with initially nonfatal PE will have a fatal recurrence, generally within a few weeks or months of the original event. Even with optimal treatment, 0.4% of patients with DVT and 5% of patients with PE will die from fatal PE, and about 25% with proximal DVT will develop postthrombotic syndrome, a chronic condition that is debilitating for patients.
VTE is now recognized as the leading cause of preventable death in hospitalized patients. Almost all hospitalized patients have one or more risk factors for VTE and 40% will have three or more risk factors. Since screening these patients for asymptomatic VTE is neither efficacious nor cost-effective, VTE prophylaxis (addressed in chapters 58, 59, and 60) forms the cornerstone for preventing these deaths. In addition, although 75% of venous thromboembolic events are diagnosed in the outpatient setting, about half of all episodes of VTE are associated with recent surgery or hospitalization. These findings stress the importance of having a low threshold to perform diagnostic testing in patients who present with signs and symptoms compatible with VTE within three months of hospitalization.
Therefore, VTE is both an acute and a chronic disease that causes substantial patient morbidity and mortality, and it is a major burden on the health care system. Costs for VTE include not only the expense of initial diagnosis and treatment, but also the cost of the complications of VTE (ie, postthrombotic syndrome, venous ulceration, chronic thromboembolic pulmonary hypertension, recurrent VTE) and its treatment (ie, bleeding). It is currently estimated that VTE costs the U.S. health care system $1.5 billion/year.