The new study found that 34 per cent of patients admitted to hospital with blood clots had been seated at work for long periods, its leader, Richard Beasley of New Zealand's privately funded Medical Research Institute, said. Deep-vein thrombosis, or DVT, is a condition in which a blood clot forms in the deep veins of the legs.

The condition can be fatal if part of the clot breaks off and blocks a blood vessel in the lungs.

The condition has been linked to long-haul flights and dubbed “economy class syndrome,” because passengers traveling coach often do not have the space or opportunity to stretch enough to reduce the risk of blood clotting.

“Being seated for long periods of time ... the risk is certainly there” of blood clots developing in the veins of the legs.

“There are considerably more people who are seated for long periods at work as part of their normal day than there are traveling,” he said, adding the main groups affected are workers in the information technology industry and in call centers.

The study covered 62 patients aged under 65 who were admitted to hospital with blood clots.

Professor Beasley said a surprise finding of the study was that “people are working for so long. We had people not uncommonly working up to 12-14 hours a day and being seated for that time”.

The 34 per cent finding is far higher than the 1.4 per cent of blood-clot patients who recently traveled on long-haul flights, and the study showed a clear link between travel and work-related thrombosis.

“It's the same thing occurring in a similar circumstance as travelers' thrombosis,” he noted.

Some reported being seated on the job for three to four hours at a stretch, “reflecting the very sedentary nature of our work at the moment,” he said.

A second study of seated immobility at work had results “very consistent with what we've found” in the first, Professor Beasley said without elaborating.

The study will be published next month in the New Zealand Medical Journal.