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Overdiagnosis — and how we need to stop harming the healthy

MRI scanner
REUTERS/Jean-Paul Pelissier
As medical detection technology becomes more sensitive, the risk of overdiagnosis grows.

The problem of medical overdiagnosis is getting increasing attention — and not a moment too soon, as noted in a commentary paper published last week in the journal BMJ.

“A burgeoning scientific literature is fueling public concerns that too many people are being overdosed, overtreated, and overdiagnosed,” writes Australian journalist and academic researcher Ray Moynihan, Australian epidemiologist Jenny Doust, and Dr. David Henry, CEO of the Institute for Clinical Evaluative Sciences in Toronto, Canada.

“Screening programmes are detecting early cancers that will never cause symptoms or death, sensitive diagnostic technologies identify ‘abnormalities’ so tiny they will remain benign, while widening disease definitions mean people at ever lower risks receive permanent medical labels and lifelong treatments that will fail to benefit many of them. With estimates that more than $200 [billion] may be wasted on unnecessary treatment every year in the United States, the cumulative burden from overdiagnosis poses a significant threat to human health.”

As the three authors point out, several factors are driving overdiagnosis (“including the best of intentions”), but technological changes lead the pack.

“The ability to detect smaller abnormalities axiomatically tends to increase the prevalence of any given disease," they write. "In turn this leads to overestimation of the benefits of therapies, as milder forms of the disease are treated and improvements in health are wrongly ascribed to treatment success, creating [as described in a 1998 study by Dartmouth University radiologist Dr. William Black] a ‘false feedback’ loop fuelling a ‘cycle of increasing testing and treatment, which may eventually cause more harm than benefit.’ ”

But the ever-broadening definition of disease (often made by health professionals with a financial interest in widening a particular patient pool) is also at fault. The diagnostic criteria for many medical conditions are now so broad that “virtually the entire older adult population [can] be classified as having at least one chronic condition,” write the BMJ authors.

“Increasingly we’ve come to regard simply being ‘at risk’ of future disease as being a disease in its own right,” they add.

Examples of overdiagnosis

Moynihan, Doust and Henry offer examples of conditions that are commonly overdiagnosed, including seven for which the evidence of overdiagnosis is particularly “robust”:

Breast cancer: “Systematic review suggests up to a third of screening detected cancers may be overdiagnosed.”

Thyroid cancer: “Analysis of rising incidence shows many of the newly diagnosed thyroid cancers are the smaller and less aggressive forms not requiring treatment, which itself carries the risk of damaged nerves and long term medication."

Gestational diabetes: “A 2010 revision of the criteria defining gestational diabetes recommended a dramatic lowering of the diagnostic threshold, more than doubling the number of pregnant women classified to almost 18%. … Critics are calling for an urgent debate before the new expanded definition is more widely adopted, because they fear many women may be over-medicalised and overdiagnosed, that the screening test has poor reproducibility for mild cases, the evidence of benefit for the newly diagnosed pregnant women is weak, and the benefit modest at best.”

Chronic kidney disease: “Controversial definition classified 1 in 10 as having disease; concerns about overdiagnosis of many elderly people.”

Asthma: “Canadian study suggests 30% of people with diagnosis may not have asthma, and 66% of those may not require medications.”

Pulmonary embolism: “Increased diagnostic sensitivity leads to detection of small emboli. Many may not require anticoagulant treatment.”

Attention deficit hyperactivity disorder (ADHD): “Widened definition have led to concerns about overdiagnosis; boys born at the end of the school year have 30% higher chance of diagnosis and 40% higher change of medication than those born at the beginning of the year.”

The authors of the commentary also announced that an international conference on “Preventing Overdiagnosis” — apparently, the first of its kind — will be held in 2013. It’s going to be hosted by the Dartmouth Institute for Health Policy and Clinical Practice in partnership with the BMJ, Consumer Reports and Bond University (where Moynihan and Doust are based).

You can read a BMJ synopsis; full text requires a subscription or payment.

Correction: An earlier version of this story incorrectly said the full text could be read on the BMJ website in full for free.

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Comments (4)

There are two separate problems....

Overdiagnosis
and
overtreatment.

The real cost (to UCare among others) is overtreatment.
This in turn is a result of treatment based more on hope than demonstrated effectiveness.
It would be better to put money into public health education than into treatments that have a ten percent chance of lengthening life by three painful months.
Lacking a treatment of demonstrated effectiveness, the best response to a diagnosis may be watchful waiting.

Another concern

With people being excluded from insurance coverage for "pre-existing conditions" on the flimsiest of grounds, I can see where this "overdiagnosis" could shut a lot of people out of coverage for conditions that will never even impact their health. And yet the Republicans keep trying to dismantle health care reform . . . . . . .

For the record

Paul, I don't have any connection with the sponsor of this column. I've never communicated with them. Nor do I consider them in any way when I select topics to write about.

My apologies

I did not intend to imply any personal relationship between you and UCare.
I could have used any medical insurance company as an example; UCare happened to be accessible.