Professor Gordon Guyatt on Bleeding in Hospitals


Professor Gordon Guyatt, MD, MSc, FRCP, OC is a Distinguished University Professor in the Department of Health Research Methods, Evidence and Impact and Medicine at McMaster University. He is a Fellow of the Canadian Academy of Health Sciences.

The British Medical Journal or BMJ had a list of 117 nominees in 2010 for the Lifetime Achievement Award. Guyatt was short-listed and came in second-place in the end. He earned the title of an Officer of the Order of Canada based on contributions from evidence-based medicine and its teaching.

He was elected a Fellow of the Royal Society of Canada in 2012 and a Member of the Canadian Medical Hall of Fame in 2015. He lectured on public vs. private healthcare funding in March of 2017, which seemed a valuable conversation to publish in order to have this in the internet’s digital repository with one of Canada’s foremost academics.

For those with an interest in standardized metrics or academic rankings, he is the 14th most cited academic in the world in terms of H-Index at 240 and has a total citation count of more than 247,000. That is, he probably has among the highest H-Indexes, of any Canadian academic living or dead.

Scott Douglas Jacobsen: When it comes to some of the issues with regards to bleeding in hospitals, what are the forms of being in hospitals that you have looked into?

Distinguished Professor Gordon Guyatt: The main areas that we have explored have been two major ones. One is bleeding related to surgery and the other is bleeding in the intensive care units. So, those are the major ones. The bleeding, the bleeding in surgery, has been the reason we have been interested in it because it is related to prevention of thrombosis.

There are two major forms of thrombosis. One is in the venous system. So, the veins that bring blood back to the heart. Clots in the veins in the legs is a common problem. It is a problem when people sit around and do not move. So, it is a post-surgical problem. As a result, it has been now routine in many forms of surgery. Any surgery that involves prolonged mobilization of any sort to give anticoagulants or anti-platelet agents.

Anticoagulants, the clotting system platelets are a little thing circulating in the blood that get the clotting process started and drugs like aspirin inhibit the platelets. Then we have anticoagulants that inhibit the clotting system.

So, we give these to people around surgery to prevent clots, but, unfortunately, anything that prevents clots causes bleeding. We also are worried about clots on the arterial side, so the most awful consequences of clots in the arterial side are strokes.

So, lots of people, lots and lots of people, around the world are using medication to prevent clots on the arterial side. People prevent it. People with heart attacks are, sometimes, using three medications to prevent clots. People who have strokes are using anti-platelet agents to prevent further strokes.

So, there are lots of people walking around taking these things. All of them increase bleeding. In the peri-operative setting, when people come into hospital, they are taking these medications to reduce thrombosis clots on the arterial side. The question is, “Should they continue through surgery or should they not continue through surgery?”

So, I have been involved in work around this tradeoff between bleeding and clotting in patients undergoing surgery.

Jacobsen: Canada has an older population than many places in the world. How does this factor into that as a consideration? People as they get older are more likely to get surgery.

Gordon Guyatt: Yes, a couple of things. First, Canada has an older population than developed countries, but they are compared to what are called developing countries or low income countries. However, it has a younger population than, for instance, Japan and Europe.

So, we are far from the oldest of the oldest. However, our populations have been getting older. People are living longer. Lifespan is increasing. Not only older people need more surgery, but we are doing surgery on older people than twenty years ago.

We would not have been doing surgery on them, simply because we would have said, “Sorry, you are too old. We almost, almost can do it.” It is rare that we say, “You are too old to anybody now.”

We are certainly doing surgery on people in their 90s. We would not have been doing that before. So, we do not turn down people who need surgery because of age much anymore. So, and clearly, the older you are, the more you are at risk of bad things happening, be they clots or bleeding.

Jacobsen: So, when it comes to the types of medications, what are some of the standard medications? What are some of the risks associated with that?

Gordon Guyatt: Commonly, aspirin is a good agent for decreasing clotting, but it is also a good agent for increasing bleeding. So, that is one. Then there is another class of drugs. Another class of anti-platelet agents, of which examples are Lipitor.

These are even more potent anti-platelet agents than is the aspirin. Then there are anticoagulants for many years’ including Warfarin or Coumadin. It was the only anticoagulant around. But in the last decade, we now have a whole army of new anticoagulants that have a major advantage from warfarin.

You needed to check the level of anti-coagulation in the blood all the time, regularly. With these new anticoagulants, you do not have to do it. You can check it. So, they have these convenience antigens.

So, these are the major drugs we are using in terms of preventing clots but causing bleeding.

Jacobsen: What is the statistical difference when someone does use an anticoagulant as opposed to when they do not – or at least when you use different ones over another or none? What are the comparative statistics in terms of the bleeding rates that would be a concern?

Gordon Guyatt: So, typically, anti-platelet agents increase or individually increase bleeding less than the anticoagulants. However, if you are taking two of them together, you are getting to a bleeding risk that might be similar to the anticoagulants.

Jacobsen: Okay, where you are going to be taking this research at present or in the future?

Gordon Guyatt: Oh! It is interesting. All sorts of things are interesting to us. It might not be interesting to other people. But one thing, there has been a huge evolution in the way people have been treating patients around surgery.

We are mobilizing much less quickly. So, this has been most dramatic in the case of hip and knee replacements, where people usually sit around. They gave them plenty of time to develop nice clots that would kill them, when the clots develop in the leg. Then they break off into the heart, into the lungs.

But the mobilized surgical technique is getting better. Now, we are getting more people out of bed right after their surgery getting them to walk around as soon as possible. It has markedly decreased the risk of clotting after surgery.

So, this question, “Do we need any of this?” So, for instance, the standard is to give an anticoagulant for up to a month after a hip replacement. However, it is not at all clear that this is necessary anymore. As a matter of fact, I am getting a hip replacement. I am going to walk.

I expect to be getting out of bed and walking around on day one. If I am lucky, I want to use an anticoagulant, aspirin, which is less effective against clotting but also causes less bleeding.

I am going to talk to my surgeon, but I am going to be using aspirin. So, because I am going to get myself up, it hurts, but I am going to walk. I am going to decrease my risk of clotting. So, that is the evolution of what is happened around surgery.

So, it is changing the way we think about things.

Jacobsen: I want to give a decades long perspective or even half century perspective to people reading this.

Gordon Guyatt: 50 years ago, people would die of their clocks. Maybe, it was same after heart attacks. Maybe, going back 60 or 70 years, we used to think it was all you. I had a heart attack. You better rest, you better stay in bed for a while. Anyway, the result was people developing all these clots and dying on their Venous Thromboembolism (VTE).

Then we decided that is not such a good idea. Now, we are getting people up. We can even be more aggressive in getting people up than we have it now. We do not have people sit around. Then maybe 40 years ago, people were still sitting around longer than we would think reasonable now.

People said, “Okay, we are the people developing all these clots. We better prevent them.” Then all of the prevention strategies came in. Now, we are saying, “Okay, got people out and maybe, we do not have to be so aggressive about preventing the clots as mobilizing. They will decrease.”

Jacobsen: Now, you gave a side comment there. You would be more aggressive. Ideally, what would be moving your most aggressive stance in terms of getting people out?

Gordon Guyatt: I am not sure. I am not sure that we cannot have people walking around the wards on the same day; they are having their heart attack, but, maybe, that is being too, maybe, aggressive.

Jacobsen: What would be a response from someone within the field to that recommendation?

Gordon Guyatt: Oh my goodness, you are having a heart attack. Please give the person a day’s rest anyway.

Jacobsen: Let’s project this project this 10 year forward, it is with things that you would know better than most of people, in terms of whether it is a new set of drugs or new evidence in terms of practice. For example, we can take on board: same day getting up, for instance, after a heart attack. What would things look in 10 years from now? Approximately.

Gordon Guyatt: It is difficult. We get surprised. So, I do not know what is going to happen in terms of drug development. I am no expert on what is the latest, even now, in what is going on in drug development.

So, a small thing that we are thinking now. One of the trials we would first is asking the question, “Do you need any anticoagulants at all?” However, if you are going to give it the traditional methodology, you would give it right after surgery.

However, the big bleeding risk is in the 48 hours after surgery, maybe 72 hours, the first day. The most in the second day, after that, the bleeding risk falls off. But the thrombosis risk goes on for a month.

So, if you are going to give anti-thrombic agents, maybe, you should wait for a couple of days before you start. On the other hand, maybe, those days are crucial in terms of setting the stage for clots that happen later.

We do not know. So, that is one of the things that I would want to sort out if you are going to use anticoagulants in surgical situations that are higher risk. When should they start? So, perhaps, one way is to view it as a trivial question, but, potentially important, in terms of minimizing bleeding risk while still getting the benefits of clot reduction.

Jacobsen: Thank you for the opportunity and your time, Professor Guyatt.

We conducted an extensive interview for In-Sight: Independent Interview-Based Journal before: hereherehereherehere, and here. We have other interviews in Canadian Atheist (here and here), Canadian Science (here), Canadian Students for Sensible Drug PolicyConatus NewsHumanist VoicesNews Intervention, and The Good Men Project (herehereherehereherehereherehereherehere, and here).

Photo by Chris Mai on Unsplash


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