Abstract
Background: Venous thromboembolism is a major cause of morbidity and mortality. Although activated protein C resistance (APC-R) is the most commonly recognized inherited risk factor for venous thromboembolism, little is known about its long-term implications on health.
Methods: MEDLINE was searched from January 1989 through August 1999 using the key words "thromboembolism," "thrombosis," "activated protein C resistance," and "factor V Leiden."
Results: One in 1000 people in the United States is affected by venous thromboembolism annually. APC-R is now understood to be responsible for up to 64% of these cases. APC-R, which occurs widely in some ethnic groups and is nearly absent in others, is due to a single point mutation in the gene for clotting factor V. As a result, inactivation of factor V by activated protein C is impaired, leading to a hypercoagulable state. This condition creates a lifelong increased risk of thrombosis and, possibly, anticoagulant therapy.
Conclusion: Family physicians have a new tool for assessing risks for venous thromboembolism. Recognizing that up to 64% of patients with venous thromboembolism can have APC-R and treating this disorder with prophylactic and therapeutic anticoagulation might reduce patient morbidity and mortality from venous thromboembolism. Screening high-risk patients might now be indicated.
Introduction
Venous thromboembolism, a serious health problem and an important cause of morbidity, affects about 1 in 1000 persons annually. It can prolong a hospital stay, it can expose patients to medications and increase their risk of developing an adverse reaction, and it is sometimes fatal. Patients who have spontaneous or recurrent venous thromboembolism could have an underlying inherited or acquired hypercoagulable state. Although patients with venous thromboembolism frequently have family histories of thrombosis, well-defined defects, such as inherited deficiencies of anticoagulant proteins, were found only in a minority (5% to 10%) of cases.