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Office workers glued to their computer screens have an increased risk of potentially fatal blood clots, a world-leading New Zealand study has found.
The study, by Professor Richard Beasley of the Medical Research Institute in Wellington found that 34 per cent of patients admitted to hospital with blood clots had been seated at work for long periods.
Painful blood clots can develop in deep veins of the legs of those who are immobile for long periods.
The clots can break off and travel to the heart, lungs or brain, causing chest pain, breathlessness or even death from a heart attack or stroke. Treatment with blood-thinning drugs can take months.
Many risk factors for clots, including smoking, pregnancy and old age, have been known. But after the death seven years ago of a 28-year-old woman thought to have developed a blood clot during a flight from Australia to Britain, "economy class syndrome" became the fear of long-distance air travellers.
It was named because of the cramped immobility imposed in aircraft economy seating, but the more-spacious business class was later implicated too.
Studies found clots had formed in 10 per cent of air travellers at high risk of the condition, and 1 per cent of all passengers.
In 2003, Professor Beasley's research group reported the first known case of life-threatening clots associated with prolonged computer use.
The man often sat at his computer, at work and at home, for 12 hours a day and sometimes up to 18 hours. He would stay at his screen for up to two hours at a time and sometimes up to six hours.
The new study will be presented at the Thoracic Society of Australia and New Zealand scientific meeting in Auckland this month and published in the New Zealand Medical Journal.
Professor Beasley said yesterday that some office workers who developed clots were seated for 14 hours a day.
"Some of them were going three to four hours at a time without getting up. These were people in the IT industry, call-centre people whose jobs really related to them and their computer.
"The major weakness of the study is that we didn't have a control group to look at the background prevalence of seated immobility at work in the general population.
"We've addressed that in a second study we've just completed. The results would be very consistent with what we've found at the moment.
"And we've just started a third, funded by the Accident Compensation Corporation, looking at the work environment in more detail.
"I think ACC's interest is really important because it is obviously recognising it as an important workplace hazard."
He agreed that deskbound computer users should take frequent "micro-pauses" from their work to stand up and stretch arms and legs.
ACC spokesman Laurie Edwards had no figures last night on claims arising from blood clots, but said such claims were not usually covered.
"The fact we've put some money into the study suggests there's enough suspicion of a connection for us to want to promote the research."
* An earlier version of this story wrongly stated that office workers were at greater risk than long-distance air travellers. The study found that 34 per cent of people presenting at Wellington Hospital with blood clots reported sitting for long hours in the office whereas only 21 per cent had recently been on a flight of more than four hours. However, the report did not take into account the fact that the former group would have been drawn from a far greater number of people than the latter.
