Prevention of Venous Thromboembolism. part 5

1.3 Risk factor stratification

There are two general approaches to making thromboprophylaxis decisions. One approach considers the risk of VTE in each patient, based on their individual predisposing factors and the risk associated with their current illness or procedure. Prophylaxis is then individually prescribed based on the composite risk estimate. Formal risk assessment models for DVT have been proposed to assist with this process. Because the approach of individual prophylaxis prescribing, based on formal risk-assessment models, has not been adequately validated and is cumbersome without the use of computer technology, it is unlikely to be used routinely by most clinicians. Furthermore, there is little formal understanding of how the various risk factors interact to determine the position of each patient along a continuous spectrum of thromboembolic risk. One simplification of this process for surgical patients involves assigning them to one of four VTE risk levels based on the type of operation (eg, minor or major), age (eg, < 40 years, 40 to 60 years, and > 60 years), and the presence of additional risk factors (eg, cancer or previous VTE) [Table 5]. Despite its limitations, this classification system, which was derived using prospective study data, provides both an estimate of VTE risk and related prophylaxis recommendations.

The second approach involves the implementation of group-specific prophylaxis routinely for all patients who belong to each of the major target groups. We support the latter for several reasons. First, we are unable to confidently identify individual patients who do not require prophylaxis. Second, an individualized approach to prophylaxis has not been subjected to rigorous clinical evaluation. Third, individualizing prophylaxis is logistically complex and is likely associated with suboptimal compliance.

After discussing several important issues related to the interpretation of thromboprophylaxis evidence, the remainder of this article categorizes patients according to the type of hospital service that is providing care for their primary surgical or medical disorder. Within each patient category, the risks of VTE and the effective methods of prophylaxis are discussed, if they are known. For most patient groups, sufficient numbers of randomized clinical trials are available to allow strong recommendations (ie, Grade 1A or Grade 1B) to be made with regard to the benefits and risks of specific thromboprophylaxis options.

VTE is an important health-care problem, resulting in significant mortality, morbidity, and resource expenditure. Despite the continuing need for additional data, we believe that there is sufficient evidence to recommend routine thromboprophylaxis for many hospitalized patient groups.

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