Does medicine have an over-diagnosis problem?

Vox

26-05-2025

covers health for Vox, guiding readers through the emerging opportunities and challenges in improving our health. He has reported on health policy for more than 10 years, writing for Governing magazine, Talking Points Memo, and STAT before joining Vox in 2017.
A new book argues doctors are too quickly and too confidently diagnosing their patients with too many medical problems. Corbis via Getty Images
Patients in the 21st century are pretty lucky. Medical science and technology have advanced so much that we can diagnose many thousands of distinct conditions, and we can even take genetic tests that scour our DNA for signs of a disease that may not materialize for decades — offering us a peek into our own future.
And with these advances, we are being diagnosed more and more. The number of people diagnosed with chronic health conditions and mental health disorders is at an all-time high — at least partly, most experts agree, because we have simply catalogued more diseases to catch.
Yet we are also increasingly anxious, anxious about our health — even anxious that we're too anxious about our health. Our ability now to understand our bodies and put a name on what's wrong with them does not always provide comfort; instead, it can create new fears and impose new constraints on us. Some health care leaders, including Donald Trump's health secretary, Robert F. Kennedy Jr., argue that we are becoming over-medicalized — too ready to take a pill for something, just for the sake of taking something.
The reality is nuanced because medicine is, to put it mildly, complicated. But we should in fact be careful about doling out diagnoses, says Dr. Suzanne O'Sullivan, an Irish neurologist and the author of a new book, The Age of Diagnosis: How Our Obsession With Medical Labels Is Making Us Sicker.
In her book, O'Sullivan argues that our eagerness to diagnose, preemptively screen, and otherwise push these new tools to their limits is creating problems that deserve to be taken more seriously. She describes mutually reinforcing trends — the patient's insistence on certainty and the doctor's desire to avoid being blamed for missing something — that are driving clinical practice toward overdiagnosis. The phenomenon is even leading to more instances of doctors diagnosing certain cancers by 50 percent or more, due to the availability of new imaging tech that can detect even minuscule traces of abnormal cells.
Overdiagnosis can cause real harm. And so O'Sullivan advocates for 'slow medicine,' in which doctors and patients take time to develop a relationship, monitor symptoms, and take a great deal of care before naming a condition — an approach that may sound quaint in an era of rapid-testing but something she says is actually more in tune with the reality that diagnosis is partly an art.
'Most diagnoses come with a huge amount of uncertainty. That covers asthma, diabetes, cancer, autism. Diagnosis is a clinical skill,' she told me in a recent interview. 'Now, the difficulty, I think, with modern medicine is a lot of people don't understand that and that they feel that the test — the blood test or the brain scan — makes the diagnosis, when actually a diagnosis is made on understanding the story in the context of the tests that are done.'
There is a tension here. Slowing down could, at least in theory, risk missing an aggressive disease early at the most crucial time — when it can still be treated. And in the United States, simply getting a doctor's appointment can be more challenging than it should be.
Each individual case is unique, O'Sullivan acknowledges, which is why a relationship with your own primary care doctor is so important. But she argues that, on the whole, doctors have erred too far in the other direction, toward diagnosing conditions too quickly and too confidently and creating a different set of problems for patients. During our conversation, we spoke about how to balance our tremendous new technological abilities with a more measured approach to clinical practice and how she would respond to critics who argue her advice would lead to people's health problems being missed.
Our conversation has been edited for clarity and length.
First, let's clarify something basic. What do you mean by overdiagnosis? How do you define it?
I think of overdiagnosis as measuring the point at which a medical diagnosis ceases to be useful. A diagnosis may be right or it may be wrong, but it isn't always beneficial in a certain situation. Overdiagnosis is trying to ask when a diagnosis is genuinely a useful way of conceptualizing someone's difficulties, and when it is not.
The first chapter is about Huntington's disease. Why did you start there?
There's a genetic test available for Huntington's disease. If you happen to have the gene for Huntington's disease, you are destined to get Huntington's if you live long enough. If you have the genetic test, you can find out ahead of time that you have that at some point in your future.
I needed people to understand the power of a diagnosis to make you sick even when you actually don't have much physically wrong with you. I tell the story of a patient named Valentina, who didn't have the gene but believed that she did because of her family history. Because of her strong belief that she had the gene, she developed all the symptoms.
When we take on a medical label, when we are told that we are sick in some way, we inadvertently search ourselves for the symptoms and signs of the label that we've been given. Our bodies are very noisy engines. There's all sorts of things to notice if you are given reason to notice.
The Huntington's disease community is in this incredible situation where they have the opportunity to find out they have a diagnosis 20 years before the disease starts. And in most countries, only 10 percent to 20 percent of people actually have the genetic test that will advise them of the disease. They do that because they are a community who has given a great deal of thought to what it's like to live with the label of an impending disease.
Once you discover you have a positive test, it completely changes your relationship with your body. It changes how you think about your health. And once you know, you can't unknow. I spoke to loads of people with Huntington's, and they all said the same thing: that living with the hope that you are negative and that everything is okay is a way better life than living with the knowledge that you're positive and waiting for the disease to start.
One of the most interesting themes in the book is this idea that people want and have come to expect concrete answers from modern medicine. Black or white: You have a disease or you don't. But you cover chronic Lyme disease, long COVID, and autism, these conditions where the boundaries are fuzzier. What problems does that create?
Most diagnoses come with a huge amount of uncertainty. That covers asthma, diabetes, cancer, autism. Diagnosis is a clinical skill. It requires a good clinician to be able to put the patient's story in the context of tests and findings.
Now, the difficulty, I think, with modern medicine is a lot of people don't understand that and that they feel that the test makes the diagnosis, the blood test or the brain scan, when actually a diagnosis is made on understanding the story in the context of the tests that are done. That means that diagnosis is hugely subjective. I hear a lot of stories of people going to different doctors who said I didn't have a diagnosis, but then the 11th doctor said I did have it.
There is an inherent subjectivity that doctors will manage differently. I'm a doctor in a highly specialized center, and I deliberately err on the side of slight underdiagnosis. I do that because I'm aware that when I make a diagnosis of a brain disease, I am changing that person's future forever.
I'm not just changing their relationship with their body. I'm also changing their mortgage payments, their insurance, their confidence in themselves, their ability to get health insurance. I'm changing their finances, their practical future. I'm changing their ability to drive. There's so many things that come with the diagnosis that people don't think about.
What many, many doctors do is they err on the side of overdiagnosis because that['s an easier place for a doctor to be. Because you're never going to come back to me and say, 'Listen, I don't really believe I had asthma when I was a child.' You'll say, 'Well, listen, I had it. You treated it and now I'm better.' It protects us against someone coming back and saying we missed something.
I came into this book thinking that something like cancer would very much be more of a yes or no. You either have it or you don't. And if you do, you really would want to know about it — as soon as possible.
And yet, after reading your book, I felt like you had complicated that story. How do we risk overdiagnosing cancer?
Within the medical community, this has been well-known for a long time, but it just doesn't leak into the general conversation. The bottom line is if you screen healthy people for an illness, any illness, be it cancer or high blood pressure, diabetes, then you will be picking up borderline cases and overtreating them.
In the case of cancer, I try to remind people we've only had MRI scans in regular clinical use in doctors' offices since the 1990s. They've only been as good as they are now in the last 10 years, as sensitive at picking up things. As we get these newer tests, we're finally seeing inside the healthy body of people.
What we find when we screen people for things like cancer is we find abnormal cells. But not all abnormal cells go into cancer. Lots of people live out their lives having these abnormal cells. They never spread. They never do anything. They never grow. They would never threaten health. But our difficulty as doctors is because we're so new to finding all these irregular abnormalities that when we find them, we don't know which ones will turn into malignant cancers and which ones won't.
So what we do is we treat them all as if they will inevitably turn into malignant cancers. One Cochrane Review estimated that if you screen 2,000 women for breast cancer, you will save one woman's life from breast cancer and treat 10 women for breast cancer who never needed to be treated.
I think sometimes we're very in love with all of our access to screening tests and scans and health checks. A lot of that care is not only unnecessary, but actually doing us harm.
One estimated that if you screen 2,000 women for breast cancer, you will save one woman's life from breast cancer and treat 10 women for breast cancer who never needed to be treated.
Obviously being able to better more precisely diagnose conditions and to test samples at a genetic level represents advancement in science and an improvement in our understanding of our own body. How do we encourage that kind of development while mitigating the problems that you're writing about?
I work with people who've got rare brain diseases. The advancement in genetics and the ability to diagnose rare genetic conditions is amazing. I don't want to in any way detract from what a phenomenal kind of medical advancement that is. I have no doubt that going forward in 20, 30, 40 years, it will continue contributing to science and to medicine in very positive ways.
How to talk to your doctor about 'slow' medicine
O'Sullivan's book is not a self-help guide, but after reading it, it's easy to come up with some strategies that could help each of us bring a 'slow-medicine' sensibility to our next doctor's appointment and potentially avoid overdiagnosis. Such as:
• Set expectations with your doctor. Make clear that you don't want to be quick to judgment or treatment.
• Press your doctor to get a better sense of how confident they are in a diagnosis, what could change their mind, what additional steps could be taken to double-check.
• If you're really worried about something, speak up. Slow medicine means being thoughtful — not ignoring what your body is telling you.
But something being modern and expensive and cutting-edge doesn't mean it's always better medicine. We need to be a little bit more open with the general public about the uncertainties.
We'll never understand the meaning of different genes to healthy populations if we don't test them, so we need to do the population-based testing. But we need to be careful before we begin offering genetic tests to unsuspecting members of the public who probably think we understand them a great deal better than we do.
We're really on a learning curve at the moment. A little bit more clarity and honesty with the public would go a long way.
How would you respond to somebody who hears we should be testing less and diagnosing less and immediately thinks, 'Well, you're just going to put my health at risk.'
Listen, I don't want a diagnosis missed in myself. I don't want to be the doctor who misses things either. So I completely understand people's fear of dialing back.
It's not about replacing all these tests with nothing. It's really advocating for this concept of slow, thoughtful medicine with good clinicians that we invest in good doctors, good nurses, good diagnosticians, and we don't feel the need to be compelled to jump into tests and diagnosis at that first meeting. We have time to spend with our patients and meet them again to discuss the problem. That's how you come to both a good understanding between patient and doctor. A quality diagnosis is made with time and understanding.