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Travel and DVT: brief update

New meta-analysis
Comment

Bandolier keeps being asked about DVTs by intrepid holidaymakers, for whom a week at Barry Island is no longer enough. A holiday is not a holiday without many hours spent scrunched up in a jet, or coach, or car. There is some more evidence from a new systematic review [1], but nothing much has changed.

Bandolier 110 reported on the incidence of deep vein thrombosis (DVT) in the population generally, and in travellers in particular. The consensus seems to be that symptomatic DVT occurs in about 50 in every 100,000 individuals in the general population. The incidence increases with age and with a number of established risk factors, and about 60% have a known cause (usually cancer or previous hospital admission).

New meta-analysis

A new meta-analysis has returned to the question of an association between air travel and DVT [1]. It found that symptomatic DVT amongst air travellers is rare, and while the incidence of asymptomatic DVT is higher, the clinical significance of this diagnosis is uncertain.

There was no evidence of an increased risk of symptomatic DVT associated with air travel (three hours or more) (OR 1.1; 95% CI 0.6 to 1.9), nor with all forms of long-distance travel (OR 1.7; 0.9 to 3.2). In one study, air travel for more than 8 hours was associated with an increased risk if there were one or more additional risk factors (OR 3.0; 1.1 to 8.2).

Comment

Given the low incidence of DVT, the analysis is limited by the small number of studies and participants. The authors suggest that we may never know if travelling, by any mode, increases the risk of DVT because studies large enough to detect significantly an increased risk would involve tens or hundreds of thousands of travellers and non-travellers, and are unlikely to be sponsored.

If there is an increased risk of DVT associated with any mode of long distance travel, it seems that it is small for the majority of us. If you have a history of DVT or embolism, it might be sensible to consult your doctor before travelling long distances.

If you have one or more other risk factors, such as heart failure, obesity, old age, it is worth considering compression stockings. All of us should be heeding the advice to avoid too much alcohol, keep hydrated, perform simple exercises, and break the journey if possible.

Reference:

  1. YY Adi et al. The association between air travel and deep vein thrombosis: systematic review and meta-analysis. BMC Cardiovascular Disorders 2004, 4: 7.

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