This is the last part of the interview with Professor Peter Dettmar.
In the last three parts, we already covered the following topics:
Part #1: The role of the stomach enzyme pepsin in LPR
Part #2: Advanced questions about the symptoms
Professor Dettmar and his team developed a test for silent reflux that is available directly to patients, as well as health practitioners. It is called “Peptest”.
The test in its current form is rather new to the market, so I had a few questions about it:
Part #4 – Peptest
Let’s get to the last part of the interview. I already used Peptest myself twice. How did you get the idea to develop a test for pepsin and LPR?
I went to work with Jamie Koufman, an international specialist for LPR, in Wake Forest Medical School, the Voice Center, in North Carolina.
And because we were working in a Voice Center we were getting a lot of patients with LPR. In fact, we’d see maybe 5,000 new patients with LPR each year.
It was at that time that we developed a first test that was able to detect whether pepsin has been refluxed by patients.
We started doing some clinical trials and started to see that in the patients who were presenting with LPR, we could detect pepsin in the region of the larynx and pharynx. We also tested a control group without LPR and did not find pepsin there.
However, those tests were invasive and time consuming. We had to collect samples through biopsies. So we realized that it would help a lot if we would have an easy to administer test for pepsin to identify the patients with reflux.
So it was probably in the late nineties when we did all that ground work. And I stayed with the Voice Center up until about 2004-2005. When I came back to the UK I and my research team developed a new and more accurate version of the pepsin detection test.
What is the advantage of Peptest over other tests that exist so far?
We wanted to develop an easy, fast and non-invasive test for reflux.
Until Peptest, all diagnostic tests for reflux were very invasive or took a lot of time.
They usually entail having a tube inserted either nasally or gastrically, often left in place for 24 hours. Typical tests for reflux are endoscopy, 24-hour pH test & impedance testing.
Yes, when I did a manometry and a 24h pH test that was way more annoying than I expected.
Exactly. So we wanted to find something which was completely non-invasive and rapid.
With Peptest you take a normal saliva sample.
How does Peptest work?
We use unique monoclonal human pepsin antibodies to detect the presence of pepsin in a patients saliva sample.
To analyze one sample takes us about 20 minutes. For the patients, it is completely non-invasive. All they have to do is to provide a salvia sample.
Pepsin should only be in the stomach. So if we are finding pepsin in the salvia, it means that you’ve had a reflux event.
Obviously, it also does depend on the concentration of pepsin found.
Many of us reflux low amounts every day, but not enough to cause significant damage. So what we’re doing is looking at is the concentration of pepsin found by the Peptest.
The good thing about being able to measure the concentration of pepsin is that we can then repeat that test after treatment, advice & lifestyle changes. We can also do it pre- and post-surgery.
We are involved with LINX, and over here in the UK the LINX surgeons do use Peptest to indicate when a patient does have reflux. Then the patients are tested again maybe two months, six months, 12 months after they’ve had the surgery.
How long after a reflux event can Peptest actually detect pepsin? So how long is pepsin in the saliva?
What we normally say is: if you’re having periodic symptoms like heartburn, cough or asthma-attacks, then just take the saliva sample within about 15 minutes after those events.
However, many reflux patients will have continuous symptoms, so for those we have to take a different approach. What we would normally do with those patients is that we would do a very early morning sample – to look for any nocturnal-type reflux. And we do another sample one hour after the midday meal and another sample one hour after the evening meal.
You are offering people to collect the samples themselves at home and send them to you via mail. Does this time-lag affect the test somehow?
Time matters.
However, we send people the tubes that they have to collect the samples with.
In those tubes is a small amount of liquid which will protect pepsin from degrading itself. Pepsin is a very aggressive enzyme, and it will digest itself unless you have this protective material in there.
We like to analyze the samples within five to seven days after taking the samples. Those are still pretty fresh samples then. You have to be careful that they don’t freeze for any reason. You must not freeze pepsin.
Patients could be anywhere in the world, really. We have a system where we can deliver the collection tubes to you by FedEx. You take your samples and FedEx will pick up the tubes from you and send them back to our lab in the UK. In some other countries, there are central labs which have facilities for testing the pepsin samples themselves.
On the website of Peptest you use the terms specificity and sensitivity to rate the effectiveness of Peptest in detecting reflux. Could you explain what those terms express exactly?
Tests like endoscopy, impedance, 24-hour pH tests and also Peptest are rated by how specific and sensitive they are.
The sensitivity is defined as to how sensitive is the test at being able to detect the presence of what you’re looking for.
For example, an endoscopy is only 30 percent sensitive for detecting reflux. It’s not really a reflux diagnostic test. If you had a 24-hour pH test for reflux disease, it’s quite good at detecting acid reflux, probably about 50 to 60 percent sensitive. However, it is very poor at detecting weak acid reflux such as pepsin reflux.
If you’re looking at something like Peptest, then depending on the concentration of pepsin found, it got a very high sensitivity. The sensitivity we quote for Peptest is 87-90 percent.
Specificity, on the other hand, means: how often is a test correct? In this case: how often are you correct in saying that someone has reflux or not? If you are right in half the cases, then the specificity is 50. A test that is always right would have a score of 100 – however that does not happen in medicine. For Peptest the specificity is about 90 %.
So when someone has reflux, could it be that the pepsin is just not reaching the mouth and the saliva, but you still have problems in your throat?
We use the Peptest in classical gastroesophageal reflux disease where you might consider the pepsin is only getting into the esophagus. What we’ve found is that we can still detect it in saliva, as it still gets up to there. So the test is used in gastroesophageal and laryngopharyngeal as well as airway and respiratory reflux disease.
There are other ways to collect samples as well. Sometimes they use a lung lavage where they wash out the lungs. So we can actually test for pepsin in quite a few different types of materials. It’s just that saliva is the easiest one to use for most patients, because everyone can produce saliva.
How many people are out there suffering from LPR without actually knowing it?
A lot of people. Especially older people. Their voice might get a bit gruffer, a bit rougher, and it might be due to reflux disease. But they just think: I’m getting older – it has nothing to do with reflux.
We did some studies in patients presenting at GP clinics here in the UK. We gave questionnaires out to see how many of those patients actually did have reflux-type symptoms.
We found it’s about 26 percent of people who have reflux like symptoms – mostly without realizing it.
So if your question is: are there people walking around with reflux and not knowing about it? The answer is yes. Absolutely yes. It’s really hard to put a figure on it, but you could probably say 10-20 percent of the population aren’t aware that they have reflux disease.
Often in some countries where it doesn’t seem to be so prevalent, it’s because it hasn’t been really recognized properly yet but the awareness of reflux is growing. We’re all built the same. So anyone can be prone to reflux disease.
However, some doctors also tend to over-diagnose LPR.
Peptest can help to make sure those patients with reflux symptoms really have LPR.
End of Part #4 of the Interview with Prof. Dettmar
This was the last part of the interview with Professor Peter Dettmar.
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