Melanie Cole, MS(Host): Medical testing is done to detect potential health conditions, and we know that early detection can reduce the risk of some serious health disorders and help clinicians to treat diseases more effectively. However, there are some screening tests that can possibly cause harm in certain situations.

Welcome to Conversations with MIT Health. I'm Melanie Cole. And joining me today is Dr. Kamau Karanja. He's a family physician and primary care provider at MIT Health. Dr. Karanja, it's a pleasure to have you join us today. I'd like you to start by telling us about some of the factors that doctors consider when doing medical testing.

Dr. Kamau Karanja: Okay. Hello. Very nice to be with you. So, there are many factors that go into deciding what tests to do in a specific circumstance. Sometimes it's as simple as what tests are available at the practice location. Sometimes there's issues around transportation or cost. But I think for the purposes of this conversation, I think the things that are sometimes more interesting to think about are some of the risks and benefits of different tests and also the relative quality of the results of the different tests that actually can vary quite a bit.

Melanie Cole, MS: So then, let's talk about things like blood tests. Are they similar as far as accuracy and importance? What are some test results seemingly ignored? Why are some test results seemingly ignored while others seem to have more significance? I mean, we used to do homocysteine, now we don't anymore. CRP, do we do that? I mean, it seems like it varies from provider to provider. Speak about blood work for a minute.

Dr. Kamau Karanja: Sure. The questions that you just asked remind me of when I started in medical school. I remember being sort of puzzled by why it seemed as though there were certain situations where some tests would be ordered and other situations or similar situations where this different test would be ordered. Or there would be situations where sometimes it seemed as though certain test results would be ignored, whereas other test results would considered definitive as far as making diagnoses.

And there is a lot of difference between tests. I think the easiest way to think about it is that there's actually a bit of a science or sort of math that goes behind a lot of testing and it's what we think about when we're thinking about which test to order. No test is perfect. Every test has the possibility of returning a result that is not accurate. And different tests are more or less likely to return results that are accurate or inaccurate. So, obviously, you want to make sure that you're ordering a test that's going to give you information that's going to be accurate. You also want to make sure that you're ordering tests that are going to give you results that you can act upon. So, something that will provide information that then leads to being able to make a diagnosis or recommend a treatment. And surprisingly, sometimes those things aren't the same.

So, I had mentioned that there was some science behind tests. The mathematical tools that are used are two different qualities of tests. One is the sensitivity of a test, which tells you how likely it is that a test is going to show an abnormality when a problem exists. And then, the other issue is the specificity of a test. And that is if the test comes back and shows an abnormality, what is the likelihood that the patient actually has that condition? So, specificity and sensitivity are two things that every test has a value attached to it. And like I said, some tests are going to be more sensitive than others, and some tests are going to be more specific than others.

What's interesting is that oftentimes these two things are actually in opposition. So, sometimes tests will be very sensitive, but not specific. And sometimes the test will be very specific, but not very sensitive. And that's where the difference is in a lot of testing lies.

Melanie Cole, MS: Why are certain tests, Dr. Karanja, discouraged? Is this about saving money or is there a medical basis for not doing some tests? is it that sometimes there are incidental findings or that something could make other tests necessary that can lead to more anxiety. Can you tell us about that?

Dr. Kamau Karanja: Yeah. So, this gets back to the same issue of interpreting the results of the tests. So, there are many factors that go into deciding whether to do a test or deciding maybe not to do a test. It could be something as simple as exposure to radiation, that might be something you'd want to avoid or expense or inconvenience. You know, I think of colonoscopies as a test that, you know, is not something that you want to rush into unless somebody really needs it.

But I think for the purposes again of this conversation, the thing that sometimes is a problem with tests is you don't want to get false positives. False positives are a big problem. You don't want to order a test that suggests that a patient has a condition that they in fact do not have. You know, that can lead to a lot of emotional distress, fear, can lead to additional testing, which might actually result in radiation exposure. Or it could lead to something like a surgery or a biopsy, which obviously would have a lot of additional risks to it. So, yeah, that's a very important reason to sometimes not order a test. If you're concerned that the chances of getting a false positive is actually higher than the chances of it revealing the condition that you're concerned about.

Melanie Cole, MS: Well then, Dr. Karanja, how are we to know, as we'd like to be our own best health advocates and we absolutely want to have that shared decision-making with our clinicians. As a primary care provider, what would you like patients to know about making that decision with their provider and when we should just look to you and say, "Yep, you know what you're talking about," or as a patient and wanting to advocate for ourselves to say, "Well, maybe let's talk about that one"?

Dr. Kamau Karanja: Yeah, I think that that's a great point. I mean, obviously we want to empower patients to be as involved in their healthcare as possible. And certainly, there are situations where patients do need to advocate for themselves and to make sure that there's enough attention and concern being paid to the symptoms that they're having. What I would suggest is a good conversation with good questions. I think a very fair question might be what are the tests that are available to look for this condition that we're maybe considering and, you know, is it an imaging test? Is it a blood test? Is it a physical examination, which is something that's often overlooked, I should add, that physical examinations can also add a lot of information that many times can actually be more valuable than what you would get from a test.

But then, I think the followup question a patient might ask, is what will we do with this result? Or what are we expecting to see from this result? and if the answer doesn't make sense, if the answer is, "Well, we're just curious, and that's why we want to do the test," well, that wouldn't be a very good reason, right? But if the answer is, "Well, this test, if it's positive, would then indicate the need to do this other test." Or, I think, another question might be, if this test comes back positive or negative, how is that going to influence how much you are concerned about whether I have the condition that we're wondering about?

So, I think a good sort of communication and questioning is really helpful. And I think every provider is thinking about these things and should be able to provide a rationale for the testing that they're doing and for the testing that they're not doing.

Melanie Cole, MS: Are there differences with how we do tests here in the US compared with other countries?

Dr. Kamau Karanja: So yes, there are a lot of differences. And, you know, some of medicine is purely based on science and some of medicine is based a little bit on tradition and culture. And obviously, traditions and cultures can vary in different places. I think, again, for the purposes of this conversation, I think a good example of this would be that there are certain parts of the world where it's very common for people to have testing done on a regular basis. That's very, very comprehensive. So, maybe a whole battery of blood tests and x-rays and ultrasounds and maybe even CAT scans and things on an annual basis as sort of a package deal. You might have heard of things like the executive physical or something. And so, this is becoming pretty common in some other countries. And the approach is very different than what we generally use in medicine, where we base the testing on symptoms, risk factors, family history, you know, whether someone smokes or drinks. There's much that goes into deciding with testing rather than just doing a boiler plate battery of tests.

So in those situations, often what'll happen is a patient will get a whole number of tests, sometimes dozens or more tests done. And then often, there will be abnormalities in those tests. And then, the question is which of those abnormalities indicate true illness and which of them are false positives. And unfortunately, what I've seen is that often there isn't a lot of information given to patients once they get these results. Often, it's, "Here's your results and you may want to go see your doctor or have more tests done to follow up these abnormalities." And this is a real challenge because it is, like I said, very different than how we often approach testing. So, sometimes I'll have conversations with patients where they'll have had a test that I would never have thought of performing, and it comes back abnormal. And then, we have to decide, "Well, what do we do with that result?" And that can be a real challenge for sure.

Melanie Cole, MS: Well, thank you for such an interesting and important episode, Dr. Karanja. Wrap it up for us. What would you like listeners to know about advocating for ourselves, about medical testing, about what you would like them to ask their physician about these decisions and what tests that you perform?

Dr. Kamau Karanja: Yeah. What I would recommend is, again, to encourage patients and people to have open conversations with their providers about what their concerns are what the conditions may be that they're concerned about, and then to ask about what testing would reveal these tests or would confirm that they don't exist. And just to keep in mind that sometimes good healthcare is getting testing done. But sometimes good healthcare is not doing tests. And those two things are important to keep in mind. Sometimes more tests is not better. Sometimes more tests can lead to distress and radiation exposures and harms to patients that they may not necessarily be considering at the time that they're presenting to the doctor.

Melanie Cole, MS: Thank you so much, Dr. Karanja, for joining us today and sharing your incredible expertise.

Listeners can visit Health.mit.edu for more information and to get connected to one of our providers. That concludes this episode of Conversations with MIT Health. Please remember to subscribe, rate and review this podcast and all the other MIT Health podcasts. . I'm Melanie Cole. Thanks so much for joining us today.