Applied Evidence

Primary prevention of VTE spans a spectrum

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References

Primary prevention of VTE in the clinic

There is no single, overarching preventive strategy for VTE in an ambulatory patient (although statins, discussed in a moment, offer some benefit, broadly). There are, however, distinct behavioral characteristics and medical circumstances for which opportunities exist to reduce VTE risk—for example, when a person engages in long-distance travel, receives hormonal therapy, is pregnant, or has cancer. In each scenario, recognizing and mitigating risk are important.

Statins offer a (slight) benefit

There is evidence that statins reduce the risk of VTE—slightly20-23:

  • A large randomized, controlled trial showed that rosuvastatin, 20 mg/d, reduced the rate of VTE, compared to placebo; however, the 2-year number needed to treat (NNT) was 349.20 The VTE benefit is minimal, however, compared to primary prevention of cardiovascular disease with statins (5-year NNT = 56).21 The sole significant adverse event associated with statins was new-onset type 2 diabetes (5-year number needed to harm = 235).21
  • A subsequent meta-analysis confirmed a small reduction in VTE risk with statins.22 In its 2012 guidelines, ACCP declined to issue a recommendation on the use of statins for VTE prevention.23 When considering statins for primary cardiovascular disease prevention, take the additional VTE prevention into account.

Simple strategies can help prevent travel-related VTE

Travel is a common inciting factor for VTE. A systematic review showed that VTE risk triples after travel of ≥ 4 hours, increasing by 20% with each additional 2 hours.24 Most VTE occurs in travelers who have other VTE risk factors.25 Based on case–control studies,23 guidelines recommend these preventive measures:

  • frequent calf exercises
  • sitting in an aisle seat during air travel
  • keeping hydrated.

A Cochrane review showed that graded compression stockings reduce asymptomatic DVT in travelers by a factor of 10, in high- and low-risk patients.26

VTE risk varies with type of hormonal contraception

Most contraceptives increase VTE risk (TABLE 227,28). Risk with combined oral contraceptives varies with the amount of estrogen and progesterone. To reduce VTE risk with oral contraceptives, patients can use an agent that contains a lower dose of estrogen or one in which levonorgestrel replaces other progesterones.27

Contraceptive-related risk of venous thromboembolism

Continue to: Studies suggest that the levonorgestrel-releasing...

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