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#4 Probiotics for the Prevention of Antibiotic-Associated Diarrhea
50 Plays2 years ago
In this episode, the What's the Proof team is shocked by the practice-changing evidence surrounding the use of probiotics in preventing antibiotic-associated diarrhea.
Also, in "Residents Ask the Darnedest Things," Dr. Caviness shares what she learned when a medical student asked about co-testing for influenza along with COVID-19 in symptomatic patients.
Most Studied Probiotics:
In adults: Saccharomyces boulardii, Lactobacillus acidophilus, Lactobacillus casei
- Dose: 10 to 50 billion CFUs per day
In children: Lactobacillus rhamnosus, Saccharomyces boulardii
- "High-dose": >5 billion CFUs per day
Episode Outline:
- Intro/background 02:00
- Evidence for use in adults 08:20
- Potential harms 15:29
- Which probiotics are recommended? 16:29
- Evidence for use in children 20:08
- "Residents Ask The Darnedest Things" 28:09
Links from this episode:
- 2017 Cochrane review "Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children" https://pubmed.ncbi.nlm.nih.gov/29257353/
- 2010 RCT on use of probiotics for AAD and CDAD in hospitalized adults https://pubmed.ncbi.nlm.nih.gov/29257353/
- 2019 Cochrane Review "Probiotics for the prevention of pediatric antibiotic-associated diarrhea" https://pubmed.ncbi.nlm.nih.gov/31039287/
If you liked the episode, please leave a positive review and subscribe! Tell your colleagues and friends!
Comments/Questions/Suggestions? Email us at whatstheproofpodcast@gmail.com or find us on Twitter @theproofpodcast!
Credits:
- Hosts: Bobby Scott, MD, FAAFP; Sandy Robertson, PharmD; Dawn Caviness, MD, BSN
- Production & Cover Art: Bobby Scott, MD, FAAFP
- Music: Twisterium, MondayHopes, Muzaproduction, and SergeQuadrado from Pixabay
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Transcript
Introduction to 'What's the Proof'
00:00:00
Speaker
You are listening to the What's the Proof podcast, where we seek to help doctors and other clinicians incorporate the best available evidence into their everyday clinical decision making. The content of this podcast is meant for educational purposes only and should not be construed as personalized medical advice. The views and opinions expressed are those of the host and guest, and no content on this podcast has been approved or sanctioned by Atrium Health.
Meet the Hosts and Episode Topic
00:00:36
Speaker
Welcome to today's episode of What's The Proof. I'm Bobby Scott and with me today is Sandy Robertson and Don Kavaness. I gotta start off by apologizing about the length of time since our last episode was published and what can I say, we got busy.
00:00:52
Speaker
This thing called life gets in the way, doesn't it, Dr. Scott? It does, yeah. But hopefully this episode is worth the wait. We'll be talking about probiotics and some of the uses for it. And I know that a lot of people probably have questions being asked of them by patients about whether they should take antibiotics. I think so. Hopefully we can help answer that a little bit today. I thought it was going to be an easy subject.
00:01:18
Speaker
We don't pick the easy ones. We really do not. And I did not anticipate how many studies and how much controversy or non-controversy it was going to be with probiotics. That might be one reason why I kept delaying the deadline. I got a little overwhelmed with the data, Bobby.
00:01:33
Speaker
Yeah, I get it.
Engaging with the Audience
00:01:36
Speaker
I do want to mention that we now have a Twitter account. You can find us at the Proof podcast. If you have comments about the show, you have thoughts, questions, please tweet us and we'd love to hear from you.
00:01:53
Speaker
We really would. We take feedback pretty well, I think. In general, we do. In general, we do. Yeah. Anyway, so Sandy, this is an interesting topic. Why did we choose this one? Why don't you share
Choosing Probiotics as a Topic
00:02:06
Speaker
a little bit about that? It is an interesting topic. And I will admit that when we don't know something, I think we're fairly good at admitting that we do not know. In this particular case, I was reviewing the in-training questions that are residents from their last exam.
00:02:22
Speaker
and specifically looking at the questions that more than 50% of our residents missed, and then I would copy those, and then we're doing that as part of our training for our conference series. One of the questions was in regard to probiotics, and what really caught my eye was they used the word, you know, what is the evidence, evidence-informed decision, and I wasn't entirely sure of the answer.
00:02:47
Speaker
So, Bobby, do you want to kind of review what that question is? Maybe we can ask the audience, our prestigious faculty, if they would get the answer correct.
00:02:55
Speaker
Yeah, I was in that session and having to review this with residents and I was surprised about it too, particularly about the strength of the evidence that the answer gave. It caught me completely off guard. Me too, me too. And I felt like as a pharmacist, I really should have known. Yeah. If there's strong evidence, why did I not know about this is kind of what I do.
00:03:17
Speaker
Absolutely. So here's the question.
Inquiring about Probiotics Use
00:03:20
Speaker
So it's a 43 year old female who comes to your clinic for a routine health maintenance examination. She has a past medical history of diarrhea predominant irritable bowel syndrome, recurrent urinary tract infections, and bacterial vaginosis. She has no new health concerns today. She does not take any medications on a regular basis and states that she prefers natural supplements to prescription medications.
00:03:45
Speaker
She says that she has heard that oral probiotics are beneficial and asks if they might be the right choice for her. Which one of the following is the best evidence-based approach to counseling about oral probiotics?
00:04:00
Speaker
A, there is no evidence that they will improve her IBS. B, there is no evidence that they will decrease the risk of C. difficile diarrhea when she is treated for a UTI. C, there is strong evidence that they will decrease the risk of antibiotic associated diarrhea when she is treated for a UTI. D, there is strong evidence that they will decrease the risk of UTI recurrence
00:04:26
Speaker
E, there is strong evidence that they will decrease the risk of bacterial vaginosis recurrence. And when I looked at this question, I was like, it could be any of them. Strong evidence. That's such a strong word. It's like either strong evidence or no evidence. All of them were extreme. So it was anxiety provoking for me. Um, so why don't you tell us about what the correct answer was?
00:04:53
Speaker
Okay, so the correct answer, and correct me if I'm wrong, I believe it's C. Yes. So repeat C for me for everyone.
Evidence for Probiotics and Diarrhea
00:05:03
Speaker
So there is strong evidence that they will decrease the risk of antibiotic associated diarrhea when she is treated for a UTI.
00:05:12
Speaker
Correct. So, answer C is based on a Cochrane review that specifically looked at probiotic use for reducing the risk of antibiotic-associated diarrhea. However, the primary outcome of this was C. diff-associated diarrhea, and we are going to review that because I had not reviewed that yet.
00:05:30
Speaker
For the purposes of the podcast today, quite honestly, Bobby, we don't have time to go over the reasons why the other options were incorrect. The data with probiotics can be quite overwhelming for lots of different chronic conditions and specific diseases. So we are going to focus on C. diff-associated diarrhea when you're taking antibiotics, and then in general antibiotic-associated diarrhea only. Is that okay?
00:05:57
Speaker
Sounds good. Don, I'm going to ask you, what exactly are probiotics? Yeah, great question. So what exactly are probiotics? They're live organisms, bacteria or yeast, thought to improve the balance of organisms that populate the gut and to potentially counteract the imbalance of pathogenic bacteria when antibiotics are taken. These organisms are thought to be needed to maintain barrier qualities of the gut epithelium.
00:06:26
Speaker
inhibit pathogens' ability to bind to epithelial cells and to help regulate the gut's immune system. According to a National Health Interview Survey in 2012, 4 million adults get this, 1.6% and 300,000 children, 0.5% in the United States.
00:06:45
Speaker
said they had taken a probiotic within the past 30 days making it the third most popular dietary supplement consumed. So this is certainly something we need to know about as clinicians. Yeah, I mean a lot of people are taking them and I would be shocked if any more than a few percentage points of those people were actually told to take one by their doctor because I think in general me included
00:07:15
Speaker
Doctors don't really feel comfortable with the evidence behind probiotics and whether to recommend them or not. Maybe I'm just not very well educated and I'm an outlier, but I feel like I'm probably not alone there in just not having a whole lot of confidence in saying, yeah, you should or should not be taking a probiotic.
00:07:34
Speaker
I agree. I agree. That's exactly my stance where I've seen some limited data, but nothing that's really changed my clinical practice. So more times than not, the patients come to me saying, Oh, I've started this. Is this good or bad? Or, and so we have to navigate that conversation. So Sandy, do you want to tell us what's the proof?
00:07:54
Speaker
I will be happy to answer, what's the proof, Dawn? Not really. This was very, very difficult for me. I don't know how many of you enjoy reading Cochrane reviews. I am one of the nerds that do, but it's quite overwhelming. When you start looking at every study and you really get interested in the details of the study,
00:08:12
Speaker
Then at about page 78, you feel like you have to just close it out and take a break and then go back to it. So I am going to try to do a quick and dirty summary for you guys on the first Cochrane review that was specifically referred to in the in-training answer.
Cochrane Review Findings
00:08:28
Speaker
This is a 2017 review, specifically looking at C. diff-associated diarrhea. There were 31 randomized control trials, 31.
00:08:37
Speaker
Okay, how did I not know this? First of all, over 8,600 participants, and these were adults and children. The majority of them were adults, however, and the vast majority of them were outpatient. Some of them were inpatient. You have to really go through the weeds to try to decide how many.
00:08:53
Speaker
So I'm not even going to give you the numbers on that, but 8,600 total. And in general, while they were all taking lots of different probiotics at lots of different doses, in general, it was somewhere between 14 to 17 days of taking the probiotic. And in general, the antibiotic was lasting about 7 to 10 days. So we think about your typical antibiotic for a week, and then you continue the probiotic for another week is how most of these trials were designed.
00:09:24
Speaker
So here's the number. The incidence of C. diff-associated diarrhea when you took a probiotic while you were taking the antibiotic in the 8,600 participants was 1.5% in the probiotic group compared to 4% in the placebo or the no-treatment control group.
00:09:42
Speaker
That is a relative risk reduction of 60%, and that was found to be statistically significant, very tight confidence intervals. The authors gave this a moderate grade of evidence, though, because the data relied heavily on five trials out of the 31, five trials where the baseline risk of C. diff-associated diarrhea was greater than 15%.
00:10:05
Speaker
So these were your sicker, hospitalized, older patients. It makes sense that those are the patients that had a greater risk of 15% baseline. Now, when you stratify it out, of course as Cochrane's do, they do subgroup analyses, a lot of them, okay?
00:10:22
Speaker
Whenever you stratify this out, they considered if your baseline risk was greater than 5%, that's a high-risk group. When they stratified those out, the incidence of C. diff-associated diarrhea in the probiotic group was 3.1% compared to 11.6% in the placebo group, and that
00:10:41
Speaker
was a 70% relative risk reduction. Again, with very tight confidence intervals. The confidence interval went from .21 to .42. And I know I'm one of the nerds that looks at these numbers, but that is extremely tight.
00:10:57
Speaker
So, in general, you would say, in a high-risk person, there's a 70% relative risk reduction of C. diff associated diarrhea. We all know that C. diff is bad, right? None of us want to treat it. We know that it has to be treated aggressively. So, this is something that was really impressive to me, and quite honestly, I was disappointed in myself that I didn't know that the data was this strong.
00:11:19
Speaker
Let me keep going. Again, they gave that a moderate grade because some of these trials do have a high risk of bias. It is very difficult in these supplement trials. And of course, there were so many different probiotics used in different routes and in different doses. So that's what makes it some of this very difficult. But for people that don't like relative risk, let me kind of put it in another way. For all patients taking probiotics while also taking antibiotics,
00:11:46
Speaker
42 patients would need to take the probiotic to prevent one case of C. diff-associated diarrhea. That's in general. For patients at higher risk of C. diff-associated diarrhea, only 12 patients would need to take the probiotic to prevent one case of C. diff-associated diarrhea.
Hosts' Reactions to Probiotic Findings
00:12:05
Speaker
So now, is that as impressive to you guys as it is to me?
00:12:09
Speaker
Yeah, for sure. I had no clue that there was that level of evidence for something that I feel like I probably could have been doing all of this time. I agree. Because we all have these terrible cases that we remember in the hospital of C. diff. This is not one day of watery stools that we're dealing with here. Yeah, I agree.
00:12:31
Speaker
Yeah, and certainly C. diff is probably the most important outcome here, but it also, the question, the in-training exam focused on antibiotic-associated diarrhea, and it didn't seem the cock review really focused too much on that. Not that one. It did not.
00:12:47
Speaker
Yeah, so there is one pretty good randomized controlled trial that I found specifically looking at antibiotic associated dietary and the probiotics they use were Lactobacillus acidophilus, also along with Lactobacillus casei, so two probiotics in one.
00:13:07
Speaker
And this study had 255 adults aged 50 to 70 years old. And they were also hospitalized and had been in the hospital for at least five days and received either penicillin, ocephalus boron, or clindamycin.
00:13:23
Speaker
And they looked at two capsules versus placebo. So two capsules I think twice a day. And looking at the outcome of antibiotic associated diarrhea. So just not just C. diff, just did they have diarrhea related to the antibiotics. And compared to placebo, the group that received the two capsules of the probiotic had 15.5%
00:13:49
Speaker
risk of having antibiotic associated diarrhea compared to 44% in the placebo group. So that's a number needed treat of three and a half. So all of your patients that you're bringing in with
00:14:01
Speaker
pneumonia or whatever else that need antibiotics, and they're going to be there longer than five days, every three and a half of those patients you are preventing antibiotic-associated diarrhea, which I'm sure, you know, lengthens hospital stays, increases the cost of the hospital stay, they end up maybe getting tested for C. diff. So there's a lot of things that downstream could potentially be prevented by something relatively simple. Right, right. Hence why, you know, answer C was correct, because this lady
00:14:30
Speaker
The reference was that she had UTIs frequently, which means antibiotics. And, you know, in our organization, cephalosporins have kind of become the gold standard for UTIs now. Right. So you really think about that. That really is consistent with what this data is showing, that there is a dramatic improvement in the amount of antibiotic associated diarrhea. Right. And you're on a cephalosporin. Right. And also in terms of the duration of the diarrhea, it was 2.8 days in the probiotic group versus 6.4 days in the placebo group.
00:15:00
Speaker
Yeah, that to me is clinically significant as a patient. Yeah, pretty solid. Yeah, when you review this with a patient, I think again, I'm a numbers gal, but if I were to hear this and I were getting ready to take a week of a selfless warrant for my UTI, that would be something that I would want to know. And again, I really feel badly that I have kind of let this go until now. So kudos to the in-training question. Yeah, learn something. Exactly.
00:15:26
Speaker
So, Don, what would you say then are the potential downsides? Because we always got to consider that when we look at any potential intervention.
00:15:37
Speaker
Yeah, that's a great question. We certainly always have to ask ourselves, this is great, this is interesting information, probably should do this. And then we have to go, wait a minute, is there any harm in this? Is there any downsides? So most of the studies instruct the patients to take probiotic for two weeks, which was usually seven days after the antibiotic was completed.
00:15:57
Speaker
So certainly taking more pills can be a hassle for some patients. That's a downside. Common adverse reactions in the trials were abdominal cramping, nausea, fever, soft stools, flatulence, and taste disturbance. But you know honestly comparing that to many medications that we use that seems pretty minimal. So I guess that leads us to the question of
00:16:20
Speaker
If I want to prescribe this, I need a pharmacist to tell me which probiotic I should be recommending. So Sandy, tell me which probiotic should I use?
00:16:32
Speaker
Oh, Dawn, that
Probiotic Recommendations
00:16:33
Speaker
is such an easy question, isn't it? Which one do I recommend? Yeah, try Googling that. There are thousands of probiotics available, and it is overwhelming, whether it's refrigerated, unrefrigerated, in yogurt form, in fermented drink form. I mean, it is really, really overwhelming. And if you think that I'm going to give you a brand name of something to recommend,
00:16:57
Speaker
You are sorely mistaken. I just I can't do it because I feel like they're just I don't want to promote one particular one over the other I want to go with what the data shows as best we have it So here's what I feel pretty confident in okay
00:17:14
Speaker
In the one Cochrane review, they specifically looked at the amount of live cells or CFUs per day that were consumed, and they did find a statistically superior outcome for C. diff antibiotic diarrhea.
00:17:30
Speaker
when 10 to 50 CFUs were used per day. And most of the time, when you look on the bottle, you can see per capsule how many CFUs it's going to be. And usually it's somewhere between 5 and 10. So within that realm, taking two twice a day, three twice a day, I don't really know. They usually have on the bottle what their recommendation is. But if you can at least hit 10 CFUs, I feel good about that.
00:17:56
Speaker
Specifically, what type of bacteria are you going to recommend? And again, most of the data, they included all comers, but in general, the most popular and the ones showing the best data was either the S. boulardii or a combination of Lactobacillus acidophilus or the Lactobacillus casei. So again, just going with the data that I have, I can't really say
00:18:21
Speaker
negative things about all the other ingredients that are in the different capsules. But they have specifically looked at these three and recommend that in the Cochrane Review. So for me, whatever form you want to use, I feel like you should be fairly confident as long as it is in a high enough CFUs and contains these particular strains.
00:18:44
Speaker
that's what I'm going to go for. I know you just want me to cut to the chase and give you one name and I'm just not your gal for that. Yeah, I think what I'm going to do is go to the pharmacy and take this list of three names here and just go look at bottles and pick
00:19:02
Speaker
You know, a couple that are each, you know, type, really. Just kind of like I do with birth control pills or all the different topical steroids. And I tell the residents, do you want to just pick one in each class? What is your local standard? This is when you can go to your specialist. You know, does your GI have a specific one? I do think you also need to look at cost. If you go on Amazon, you can find
00:19:24
Speaker
a $10 probiotic or a $100 probiotic. It's very, very difficult. Do I think that you have to get the most, is the most expensive the best? I know. Let's don't do that. But is the middle of the road? I mean, I don't know. Sometimes it gets very, very difficult to know which one to pick. I will confess that in the past when patients have asked me which one to pick,
00:19:47
Speaker
I would hedge a little bit and say, you know, you usually kind of get what you pay for thing. And probably misled patients unintentionally into buying more expensive probiotics than they needed. But hopefully now I'll be more informed and our listeners will be too and nobody will have to do that. I agree. I think that's smart.
00:20:08
Speaker
Okay, so as family doctors, we don't take care just of adults. We also take care of kids. Yes, we do. And kids need antibiotics quite a lot. So is there any evidence about use of this in children to prevent antibiotic-associated diarrhea?
00:20:25
Speaker
Yes, there is. And so this is going, you know, outside of what the in-training question was asking about the 43-year-old adult female. But I did find a 2019 Cochrane review that specifically looked at antibiotic-associated diarrhea in children.
Probiotics for Children
00:20:40
Speaker
Again, a lot of trials, 33 studies, over 6,000 children between the ages of three days and 17 years.
00:20:48
Speaker
The majority of these children were treated outpatient, and just like in your study, Bobby, it was amoxicillin, cephalosporins, and then clendamycin kind of in that order with the beta-lactams being the big majority of the antibiotics. There were some kids that were hospitalized, but the majority of them were outpatient.
00:21:07
Speaker
The majority of them were also otherwise healthy children. And they were reporting diarrhea between five days and 12 weeks after a course of antibiotics. And honestly, the 12 weeks to me is a stretch. It's hard for me to say, okay, 12 weeks later, now you have a day of watery stools.
00:21:24
Speaker
Can I really blame the amoxicillin three months prior? But that is how the studies, that was the standard for the studies, was to go out to that. The way they defined moderate diarrhea was three or more watery stools in 24 hours, and then mild was one to two watery stools in 24 hours. So they really were looking at a good amount of diarrhea. So the probiotics used in this Cochrane Review, again,
00:21:51
Speaker
the Lactobacillus species, the Streptococcus species, the Saccharomyces species. I mean, all kinds of species were allowed in the probiotic group. So again, when you're going to ask me what specifically should I recommend to children, I'm going to say there are a lot of studies that include a lot of different species. So here's the overall numbers. Because again, it's pretty impressive. Antibiotic-associated diarrhea was 8 percent
00:22:20
Speaker
compared to 19% in those children that took the probiotic for the time that they were on the antibiotic and then for at least a week after. Okay, so that number needed to treat is just nine. So nine kids would have to take a probiotic.
00:22:35
Speaker
for a couple of weeks in order to prevent one case of at least moderate or mild diarrhea. So that's pretty significant when you're talking to a parent, in my opinion. Yeah, I mean, I wonder how long it'd take me in clinic to get to nine kids that I prescribe antibiotics to.
00:22:51
Speaker
Right. It's not going to take very long. Now, I will tell you that, you know, there are a lot of studies that were at high risk of losing them to follow up. There were some biases and the Cochrane Review does a fantastic job of adjusting for all of these biases. And they did still find a significant improvement. But when they took out 19 studies,
00:23:10
Speaker
that had any significant loss to follow up, there was still a statistically significant improvement in the rates of diarrhea, but it wasn't as robust. That went from 12% in the probiotic group versus 19% in the placebo group. Now, when they further delineated high-dose versus low-dose probiotic,
00:23:32
Speaker
And they defined high dose in children to be greater than five billion CFUs per day. So slightly lower dose than the C. diff. So we're talking five billion CFUs per day. When they compared specifically those studies, the data was again very robust. 8% incidence of diarrhea in the probiotic group versus 23% in placebo. Wow.
00:23:57
Speaker
I know, it's impressive. Excuse me, the ADRs that are associated with the probiotics, very similar to what Dawn has already reviewed, some nausea, gas, flatulence, a little bit of abdominal bloating. It was defined as infrequent. You know, how much of this is related to the antibiotic. There's so many, the disease process, it's very difficult sometimes to assess ADRs. But in general, I don't feel like we're
00:24:22
Speaker
being harmful to the child whenever we are giving a probiotic because diarrhea can be very problematic. We all know they can't go to school. We can't go to daycare. There's so many things that come with with diarrhea. Yeah, and it's always fun to be able to tell people to take five billion of something. I know. Like five million billion, whatever, whatever. It's a lot. Just look on the bottle. It's a lot. It's a big number.
00:24:44
Speaker
Now I will have to say, and I'm going to admit to you that I did not specifically look up these observational studies, but in this Cochrane Review, they wanted to make sure that there have been some serious side effects reported in observational studies in severely debilitated and immunocompromised children with underlying risk factors such as
00:25:05
Speaker
those with central venous catheters in long-term, disorders that are associated with already bacterial and fungal translocation. So I would not recommend it at this time in a very, very sick immunocompromised child. These are in your otherwise relatively healthy children that you're treating with otitis media, respiratory infections, et cetera, et cetera, with broad spectral antibiotics. That is what I can feel confident with at this point. Yeah, that makes sense. Yeah.
00:25:32
Speaker
So, the big question at the end of the day, and I'm going to ask it, and then I'm going to answer it myself, and then I'm going to turn it over to Bobby, and then we're going to go to Dom. How likely, based on this data, are you to recommend a probiotic to either a child or an adult who is also taking antibiotic?
Final Recommendations on Probiotics Use
00:25:48
Speaker
And I have to admit to you that I feel like at the very least it is a discussion that needs to be had with the patient or the parent or whoever has that child there. C. diff is a big deal to me. And if I myself now were sick and needed to take an antibiotic, it is something that I would consider in general. I feel like it is safe. I feel that it is relatively affordable.
00:26:18
Speaker
And we're not talking about long-term probiotic use. I'm talking about taking something for two weeks. So for me, the recommendation is going to be yes, to at least suggest it and to try to remember some of these numbers to suggest to the patient or the parent. And I feel pretty good about that.
00:26:35
Speaker
Yeah, I gotta say, I am a lot more likely to prescribe it now compared to a couple weeks ago. I mean, look at these number needed treat numbers of 42 for adults, nine to probably 12 or so in kids. That's...
00:26:54
Speaker
Pretty good. I mean, that's better than statins for, uh, secondary prevention, right? Right. So, I mean that, and it's, there's some flaws in the study, but you know, when you consider that along with potential harms, which seem to be very low, potential benefits seem to be pretty great, especially when it comes to C. diff prevention. It's going to take a lot, I think, to make this not part of my routine standard practice at this point.
00:27:21
Speaker
Well, I'm glad that we forced ourselves to go through it then, right? Yeah. Yeah. And I'm going to try to be teaching all the residents about it too. So, Don, what do you think?
00:27:30
Speaker
Yeah, I agree. I really want to disagree just for conversation sake, but I do agree. Go ahead and disagree if you want to do it. I mean, it's hard to disagree with this data. And then, like you said, the number needed to treat. And I think the biggest thing to my bias, because I've seen children sick in the hospital with C. diff, I've seen adults sick, you know, certainly we bring that bias as well. But the data does support it. And I think I'm going to have to change my clinical practice. So thanks for
00:27:59
Speaker
going through all this with me. Yeah, and you all listening, if you have an opinion, tell us what you think. Shoot us a tweet on Twitter or send us an email. We'd love to hear from you. But we're going to shift gears now to residents ask the darndest things. Okay, Dawn, so you had a medical student actually, not a resident this time, ask you a question in clinic recently, correct?
00:28:27
Speaker
Yeah, so we were seeing patients together and I had an eight year old healthy female come in with a viral illness. We actually did a car visit. And before I saw the patient, my assistant that day who typically works with another provider had already done a COVID and a flu swab. And she had given me the results and the patient was positive for flu. And the medical student asked me,
00:28:53
Speaker
Oh, do you always swab all patients with viral symptoms for COVID and flu? And I said, that's a great question. Let me find the answer to that because, you know, what we did before COVID and what we do now after COVID, it looks different.
00:29:13
Speaker
So yes, I was not sure how to answer her question. I told her what I have done historically, and then I went to look for an answer, which was not easy to find. So I like it whenever they ask a question. I can show them exactly what point of care resource I used so that they can find it in the future, and then it's done. But this was not that kind of question, unfortunately.
00:29:38
Speaker
So I first went to our point of care resources that we use in clinic and really couldn't find an answer, kind of what's our standard? Is there any data to support co-testing? And then I went to Google and said CDC NIH guidelines, infectious disease guidelines, and I actually did find some information that I could share with my medical student so I wasn't empty handed. And I'll go through that with you if you'd like. Yeah, that'd be great.
00:30:07
Speaker
So what I found was lots of strong to moderate recommendations, but all based on expert opinion. And that's not surprising, right? Because that's kind of what we've been dealing with in COVID because of time and other restrictions. So basically the things that I went through with a medical student and things that the NIH and CDC had put in their documents was
00:30:34
Speaker
the signs and symptoms of uncomplicated, clinically mild influenza overlap with those of mild COVID. And even though I really didn't pay attention before, it's documented that loss of taste and smell can occur with flu. So you can't really rely on that. Even though it is more common with COVID, you can't really rely on that.
00:30:55
Speaker
So really, because we have limited data, the experts are saying, hey, just like before COVID, if you highly suspect if it's going to change your management, yes, co-test. Saying that, I think a lot of times, patience.
00:31:10
Speaker
really push us to test because their work or the daycare is asking, what is this? Is this COVID or not? Is this flu or not? So I think sometimes we test it, even though it's not gonna necessarily make our patients healthier or decrease hospitalization necessarily, we are pushed to do this right or wrong. There is a price tag to that though. I actually asked my lab, out of pocket, our test for just flu is $49.
00:31:39
Speaker
But a lot of patients would say it was worth it to them to know how to isolate their family, how to talk to their contacts. So I don't know. I guess the point in sharing this is to show that, yeah, sometimes medical students and residents are going to ask us things that there's just not a great answer for and we have to use our clinical judgment.
00:31:58
Speaker
And we have to look at each clinical scenario and each family and just do our best. And then, you know, I could show her this data and say, hey, here's expert opinion data. I don't have any studies. And that's, that's okay. Yeah, I think you're never going to have
00:32:14
Speaker
a whole lot of studies that are going to just tell you who to test and who not to. But I think there are some things that you can use in an evidence-based approach and how you go about testing. So you think about pretest probability. In general, when you do any test, you really shouldn't do it if the pretest probability is low, which is generally considered less than 10%.
00:32:38
Speaker
or if it's really high, greater than 90%, because the test isn't gonna help you in that situation. If it's positive but the pretest probability is low, then it's gonna be still doubtful whether it's a true positive or not. And likewise, if it's negative but your pretest probability is super high so that you have a patient that lives with two other people that have flu and they come in and they get tested and it's negative, you're just not gonna believe it if they have classic symptoms.
00:33:08
Speaker
I guess in the student situation, I would point out, we don't always use absolute terms like always and with all patients. So you need to consider that. But in general, that pretest probability is going to vary. So it's going to vary somewhat on the prevalence of what's going on. So like when you test for influenza in July,
00:33:32
Speaker
versus when you're going to test it in January or February, you know, it's probably a lot different because the pretest probability changes a lot over that time. So those are the things you got to think about. People generally aren't going to know sensitivity, specificity in terms of statistics, but you might know just ballpark figures. But the real question is positive predictive value, negative predictive value, which you're going to vary with prevalence too. But you're right. In general,
00:34:02
Speaker
you know that's just a judgment call. Yeah and the reason you know it's interesting this didn't come up until May this question right because really this kind of little uptick in flu and now COVID cases we've really been focused on COVID because the prevalence pre-test probability was so low but then it's kind of upticked a little bit and now that's back on our radar should we be now you know it's a pre-test probability higher so
00:34:27
Speaker
With this particular case, she did live with her grandmother. They were really happy to have the information. It was fine. They had insurance to cover the test always well, but it was still interesting to kind of walk through that with the medical student. Yeah, this is good exercise too. And that's what great thing about teaching is, is that they keep you sharp. They ask you these questions that you sometimes don't know the answer to and you have to look them up and you learn and you both of you get better because of it. Well, thank you, Dawn. Yeah.
00:34:56
Speaker
And that's going to wrap up our show today. Thank you very much for listening. If you enjoyed the podcast, please leave a review and hit that subscribe follow button in your podcast app of choice. For any questions or comments about today's episode, drop us an email at whatstheproofpodcast.gmail.com. We'll see you next time.