By Jennifer Berube
A day at the office is becoming risky business.
Researchers believe people who sit at their desks for prolonged periods of time could be risking their lives. The seemingly cushy office job is actually associated with a high risk of developing blood clots in the legs, and if left untreated, these blood clots can be fatal.
In a recent series of studies, the Medical Research Institute of New Zealand proved that prolonged seated immobility at work is a common risk factor for venous thromboembolism (VTE), a condition where blood clots occur and travel through the veins. When a blood clot forms in the deep veins of the legs, thighs or pelvis, it is known as deep vein thrombosis (DVT). When this blood clot breaks off from its original location and travels through the venous system, it can become lodged in the arteries leading from the heart to the lungs. This blockage is a serious condition called pulmonary embolism (PE). So basically, DVT + PE = VTE.
Now that we’ve got the math out of the way, let’s move on to history. In 1940, Prof. Keith Simpson reported that VTE was first recognized in World War II, during the London Blitz. He said the incidence of fatal pulmonary embolism increased six-fold in people who sat for prolonged periods in air raid shelters. This was thought to be caused by sitting in the deck chairs in cramped conditions. In 1954, Dr. John Homans published evidence that VTE may be associated with air travel. In the decades since, this theory has become a mainstream argument and has been dubbed ‘Economy Class Syndrome.’
“We know that if you sit for prolonged periods on a single air flight, that you increase your risk of getting a blood clot,” says Prof. Richard Beasley, study leader at Wellington Hospital in New Zealand. “So it’s not surprising whatsoever, that if you sit for prolonged periods at work that you’re also at risk.”
Prof. Beasley and his team conducted the first case-control study investigating the potential role of seated immobility at work and risk of venous thromboembolism. The results show the maximum number of hours seated at work is significantly associated with VTE, with the risk increasing by 10 percent per hour longer seated. Similarly, the maximum time seated without getting up is also associated with VTE, with the risk increasing by 20 percent per hour longer seated.
“One of the things that amazed me is just how long people sit without getting up”
“It’s an interesting observation and when I first heard about it, I thought that’s silly, but in fact it makes some sense,” says Dr. Mark Crowther, Chair of the Division of Hematology within the Department of Medicine and Professor of Medicine at McMaster University, about Prof. Beasley’s study. “We’ve known for a very long time that, for example, immobilization after surgery increases your risk of developing blood clots and airline travel is a weak risk factor for blood clots and I’ve actually seen cases of people who have suffered blood clotting complications in whom the only real explanation was periods of prolonged immobilization sitting. I think it’s certainly a very valid observation.”
But, as much as he agrees that there may be a risk factor involved with seated immobility at work, Dr. Crowther points out it is a minor one. “My concern would be that people would suddenly think that there’s an epidemic of blood clots associated with this because there aren’t.” He says one way to figure out whether things cause blood clots is to look at the factors and assign them risks. “The risk ranges from mild additional risk factors and sort of in the mild additional risk factors would be things like airline travel and probably the birth control pill. Then we have moderate risk factors, which are probably most forms of surgery. Then we have high risk stakes, which are some of the more aggressive surgeries and things like cancer, so this would fall into the mild risk factor category I would suspect.”
While prolonged seated immobility may be a mild risk factor for this under-recognized condition, venous thromboembolism is fast becoming a major health concern. Statistics published by The American Heart Association estimated that more than 250,000 patients are hospitalized annually with VTE. The same report stated that death occurs in about 12 percent of PE cases and about six percent of DVT cases within one month of diagnosis.
“One of the problems is that DVT is a disease that has a very subtle presentation and you often think you just strained your calf muscle or you just got a bit of discomfort in your calf, or a little bit of swelling,” says Prof. Beasley. It may come and go a bit, or it may progress without the patient even knowing it. DVT and PE may also occur over a period of days or weeks and since they can be so subtle, it can be difficult for a doctor to make a diagnosis.
“The two most common clinical manifestations of a blood clot are leg pain and swelling that you can’t explain,” states Dr. Crowther. “In particular, pain and swelling which is unusual for you and which doesn’t go down overnight. The classic story is the person has two legs that look the same on Tuesday and by Thursday morning one leg is twice as big as the other one and red and tender. There are a number of things that can cause that, but one of the important ones would be a blood clot. If they move to the lungs, which they can sometimes do without causing symptoms in the leg, they can cause unexplained, but persistent, shortness of breath or chest pain that feels like being stabbed by a knife.”
So, the best way to avoid getting a blood clot is to stay mobile. Get up more often at work, go for a walk.
“The strategy of getting up and walking around is probably a wise one for lots of different reasons, again the likelihood that you, on an individual day, are going to develop a blood clot is pretty doggone low, but remaining immobilized for long periods of time is probably not good for you for lots of different reasons, least of which you’re not getting any exercise,” says Dr. Crowther. “The blood clots that are of the worrisome sort, those are the deep vein thrombosis that we’re talking about, don’t go away on their own so the natural history of them is that they develop and you develop symptoms from them and if they’re untreated, the general thought is that they continue to get worse until they cause a major medical problem, most frequently pulmonary embolism.”
Prof. Beasley agrees. “I think that what we’re hoping is there be a change in terms of the work practices, where people don’t sit for such long periods in front of their computer. One of the things that amazed me is just how long people sit without getting up. That was a real surprise to me was that how many people sit for three or four hours at a time without getting up at all, and that clearly is not healthy, and not just in terms of the circulation, but also in terms of your mental concentration and your general physical well-being.”
Since many offices revolve around computers, there has been an unhealthy shift in the evolution of work habits. With everything available at our fingertips, there is less and less reason to move around the office, making it common practice to remain seated at a desk all day. This static position is not only a risk factor for venous thromboembolism, but a frontrunner for causing circulatory problems and muscle fatigue, as well as hindering mental concentration and productivity. So, don’t just settle into the routine of a day at the office. Get up, stand up against prolonged immobility.