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How can we address these limitations?

Helen Pardoe and Marie Parsons have a discussion about addressing the limitations of PCT.
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Hi, there. We’re going to have a discussion today about the costs, limitations. What is it that limits people’s use of procalcitonin? And I’m here today with Dr. Marie Parsons. Hi. I’m Marie Parsons. I’m a Consultant Clinical biochemist, and we have recently introduced procalcitonin here into our laboratory and into our hospital. So in some hospitals, there’s concerns about the cost of procalcitonin. How have you addressed it? And what would your recommendations be? Right, so procalcitonin is, in the grand scheme of laboratory tests cost, it’s not that great. It’s about 14, 15 pounds, but that very much depends on the analytical provider that you use. Now, most immunoassay tests are more expensive.
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And, for an example, a TSH would cost about 10 or 11 pounds, so we’re looking at a cost difference of about 3 pounds. And I personally think that that’s not too much of a difference for a test that could potentially save someone’s life. Right, and what about the availability of procalcitonin? Have you had any problems? No. Not at all. Procalcitonin is available on all the major analytical platforms and laboratories. Obviously, there are different assays. There are also numerous points of care tests available. So availability is not really an issue. There are plenty of good validated assays out there, and there’s also plenty point of care equipment as well. Yes.
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Certainly, as a clinician, I’ve never had a problem with requesting procalcitonin, finding points of care testing availability, so certainly, I don’t see procalcitonin availability as a blocker to us using it routinely in clinical practice. Not at all. It’s something really it’s about a culture change within hospitals really that’s going to encourage its usage further, in my opinion. So why do you think that there is some resistance to using procalcitonin? Because if we look as a clinician, we use c-reactive protein routinely, on a daily basis in many patients, and that is a common problem throughout many hospitals. We use it in accident and emergency. We know its limitations. Yeah. And don’t get me wrong, there are limitations to PCT as well.
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Things like it can be falsely raised in pregnancy, in surgical trauma, in people with autoimmune diseases. But all tests can have false positives and false negatives. And if we know what they are, we can manage them. It’s just like with drugs, with contraindications. If you know what they are, you manage the patient group that you give them to, and you deal with it. But it doesn’t preclude its use. Yeah. Do you think there’s any sort of reason why we shouldn’t be using it to help guide antimicrobial therapy? What about in accident and emergency? I think people are very worried. They wouldn’t want to stop antibiotics in accident emergency, would they? No.
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And I would never, never want that because I don’t think that would be right. But what it can be used for quite effectively is knowing when to stop. Or if antibiotics are started and then it becomes apparent that this is not a bacterial infection, it gives a good solid indicator at the point and gives you reassurance that you can effectively stop. Because procalcitonin does have a good profile of sensitivity and specificity for bacterial infection, doesn’t it? Yes. It does. It does. The thing with it and that can cause an issue is that there’s a lag phase with it. So if you measure the PCT too early on in the infection, it may actually be negative.
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So we would always recommend that there’s a repeat procalcitonin done 24 to 48 hours later. Well, but isn’t there a lag phase with c-reactive protein as well? There is, but it’s not quite as long. Right. Yeah, and the lag phase almost becomes a moot point with CRP because everybody overuses it. Right. So nobody really pays attention to the lag phase because once they’ve identified that CRP is raised, it gets measured and measured and measured and measured. So for most patients, you could draw a beautiful profile of what’s happening. Is that what you see as a clinical biochemist?
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That’s what I see as a clinical biochemist to the extent that we actually have a rule written into our computer system that you cannot have a repeat CRP on consecutive days. Right. OK. It will be rejected if that happens. So with PCT, obviously, we actively encourage that second one to the extent that there is a comment put on every PCT that goes out that states what the lag phase is and states that there should be a repeat done. And do you think there’s benefit for continuing PCT measurements outside of ITU, or do you really think just those first two? No.
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Obviously, if a patient is on antibiotics and you’re unsure as to how well they’re responding clinically, PCT can also give you a very good indicator of what might be happening with them.
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So do you think we’ve got a good level of knowledge within our prescribing community on how to use procalcitonin, or do you think we could be better? I think we could definitely be better. Because as a medical community, we’re quite slow sometimes to adopt new practices. And there’s a fear that if you’re asked to follow numbers for anything, there’s a fear that the numbers can be wrong. But nobody’s asking anyone to follow numbers in isolation. Right. You know, that’s the same with all tests. You shouldn’t be treating the number. You should be treating the patient. Yes. And the patient is more than that number. And unfortunately, sometimes, in my practice I see that patients aren’t being treated that way.
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Sometimes they’re being treated as the number on the page. Right. So with a high CRP, people are continuing intravenous antibiotics. Yes. Even in the presence of two levels, that would be on the BRAHMS criteria, very much not a bacterial infection. Yes. Very much so. And this is the thing. That premise applies to everything we do with patients, every test that we run. Every test should be looked at in combination with what you’re doing, what your patient is showing you, and you have to make a decision about how you move forward on the basis of all of those things, not just the number that’s being presented to you. I understand the fear. I really, really do.
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But it’s about having that change in culture. That it’s OK to bring all of those things together, and clinical acumen will always be at the top of the list. Yes. Always. But these tests are here, and the criteria and the guidance are here to support that clinical acumen. But the clinical decision will always be that of the doctor in the end. Do you we have any other biomarkers that are as good as PCT at identifying bacterial? Not at the moment. So for the current practice- For the current practise, PCT is the best on the market. Yeah. Otherwise, I wouldn’t have introduced it.
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Essentially, I wouldn’t have agreed to introduce it if it wasn’t the best available on the market at the time. And if something else that’s better comes forward from the literature or whatever in the future, then we can review it, and we’ll review our practices. But for the moment, PCT is really the best where it’s at for doing this kind of work, in my opinion. So let’s not underestimate as clinicians, your clinical biochemist is the person who has control of these biomarkers. You may want them. So maybe that’s the first person you should be looking at if you want procalcitonin in your organisation. But certainly the evidence is there. You certainly always need the lab support. Absolutely. Definitely.
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It’s part of the team. It’s a key part of the team. And we love nothing more than to work with our clinicians. We don’t get asked often enough, really. So we can help, and we can add value if we’re given the opportunity to. So, the answer to success would be the test may be slightly more costly. It’s not significantly more than other tests. And the benefits can be reaped by a reduction in your antimicrobial prescribing. Yes. And your length of stay. Yes. Length of stay. What can you do? You can work closely with the laboratories. And it certainly is a new biomarker that’s a great benefit. Can I just say thank you, Marie? No problem at all.
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Any final words because I believe that you’ve got personal experience with sepsis. Yeah. So I have a seven-year-old son who has had sepsis twice. And in both cases, he was treated at a laboratory who was an early adopter of PCT. And in both cases, it was used to help manage him and his antibiotics. And he is, as Helen will attest to, he is a very cheeky, very healthy seven-year-old now. And the treatment and the management of his sepsis, which included PCT, very much is responsible for that. And I couldn’t be more grateful. Thank you, Marie.

In this video, Dr Marie Parsons and Helen Pardoe have a conversation about the limitations of PCT use.

One limitation of the use of PCT may be the cost for hospitals. It is relatively expensive in regards to laboratory tests but most immunoassay tests are more expensive. Falsely-raised levels of PCT may also be a limitation. This can occur in situations such as pregnancy, surgical trauma and autoimmune disease patients.

There is a lag phase in PCT which may give false readings if the measurement is taken too early on in the infection but this can be combated by taking a second reading 24-48 hours later, which is actively encouraged.

Dr Parsons also discusses how PCT should not be used in isolation. Its use in patient care should always be supplementary to the clinical judgement of the healthcare professional.

The video concludes with an interesting discussion of Dr Parson’s personal experience with the use of PCT.

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Procalcitonin: PCT as a Biomarker for Antimicrobial Stewardship

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