Air Travel and Venous Thrombosis: How Much Help Might Aspirin Be?

Yoon K Loke, MBBS; Sheena Derry, MA

In This Article


The results of applying a 29% risk reduction to different risk levels of DVT are shown in the Table 1 . For example, if the overall incidence of DVT due to long-distance travel is 20 per 100,000 travelers, then 17,000 patients will need to be treated with aspirin to prevent 1 extra DVT. The figures in the Table 1 can also be used to roughly estimate the effects of aspirin in the 3 case scenarios presented earlier.

The effect on the average individual, such as the woman in case 3, would be to lower the baseline risk of 0.02% (20 per 100,000 long-distance journeys) by 0.0058%, to give a risk level of 0.014% with aspirin therapy, and an NNT of 17,000. In contrast, her 60-year-old smoker husband (case 2) may be at twice as much risk, with a baseline incidence of greater than 40 per 100,000, and an NNT of 8600. We would expect the 23-year-old medical student in case 1 to have a below-average risk (say 10 per 100,000), and a NNT of about 34,000.


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