Report: 33% of adults recently diagnosed with asthma do not have it

Duh… I wrote about the phenomenon of asthma overdiagnosis 14 years ago… and what are the implications for EPA air pollution junk science?

The media release is below.

My 2002 article is below that.

As to the implications, suffice it to say that this reality further debunks EPA’s junk science-powered weak statistical associations on asthma and air quality.

Also read: Ozone Triggers Lying Not Asthma.


Study finds 33 percent of adults recently diagnosed with asthma do not have it


A new study published in the Journal of the American Medical Association found that 33 percent of adults recently diagnosed with asthma by their physicians did not have active asthma. Over 90 percent of these patients were able to stop their asthma medications and remain safely off medication for one year.

“It’s impossible to say how many of these patients were originally misdiagnosed with asthma, and how many have asthma that is no longer active,” said lead author of the study Dr. Shawn Aaron, senior scientist and respirologist at The Ottawa Hospital and professor at the University of Ottawa. “What we do know is that they were all able to stop taking medication that they didn’t need – medication that is expensive and can have side effects.” Eighty percent of the participants who did not have asthma had been taking asthma medication, and 35 percent took it daily.

The study also found that doctors often did not order the tests needed to confirm an asthma diagnosis. Instead they based their diagnosis solely on the patient’s symptoms and their own observations.

“Doctors wouldn’t diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an x-ray,” said Dr. Aaron. “But for some reason many doctors are not ordering the spirometry tests that can definitely diagnose asthma.”

The study looked at 613 randomly selected patients from 10 Canadian cities diagnosed with asthma in the last five years. After a series of detailed breathing tests followed by consultation with a lung specialist, asthma was ruled out in a third of these patients.

The research team was able to access the medical records of 530 of the patients to see how they were originally diagnosed. They found that in 49 percent of these cases, physicians had not ordered the airflow tests required by medical guidelines.

When the patients that were found not to have asthma were re-diagnosed, most had minor conditions like allergies or heartburn, and 28 percent had nothing wrong with them at all. Two percent had serious conditions like pulmonary hypertension or heart disease that had been misdiagnosed as asthma, and went on to receive proper treatment.

“It wasn’t a surprise to most patients when we told them they didn’t have asthma,” said Dr. Aaron. “Some knew all along that their puffer wasn’t working, while others were concerned that they might have something more serious. Thankfully, the majority of the conditions were mild and easily treated.”

Retired nurse Becky Hollingsworth was diagnosed with asthma two years ago. While participating in this study she learned that her shortness of breath was actually a temporary breathing problem left over from a bout of pneumonia.

“I was delighted we could verify that I did not have asthma,” said the 72-year-old grandmother. “Even if it’s falsely diagnosed, you still have to deal with the consequences of having a chronic illness. You have to take medication and if you want to take a trip somewhere the insurance can be higher.”

This study confirms and expands on the findings of Dr. Aaron’s 2008 study which suggested that 30 percent of asthma patients had been misdiagnosed. According to a 2010 Statistics Canada survey, 8.5 percent of Canadians aged 12 and over have been diagnosed with asthma. In many cases asthma is a life-long condition, but sometimes it can become less active or go away entirely.

“We need to educate physicians and the public to get the diagnosis right in the first place,” said Dr. Aaron. “Patients who have difficulty breathing should ask their doctor to order a breathing test (spirometry) to determine if they might have asthma or even Chronic Obstructive Pulmonary Disease (COPD). Similarly, if patients think they may have been misdiagnosed with asthma or that they no longer have asthma, they should ask their doctor for a spirometry test. Asthma can be deadly, so patients should never go off their medication without speaking to a doctor first.”


Dirt-Asthma Link Needs Scrubbing
By Steven Milloy
September 20, 2002

Cleanliness may be causing children to become asthmatic, researchers suggested this week.

It’s a wacky idea that seems to be getting attention thanks to the oft-parroted factoid that childhood asthma has soared over the last 20 years.

A study in the Sept. 19 New England Journal of Medicine reports that exposure to bacterial substances in dust from mattresses was weakly correlated with reduced rates of asthma and wheezing among 812 children living in rural areas of Europe.

The editorial accompanying the study, “Eat Dirt — The Hygiene Hypothesis and Allergic Diseases,” set the tone for media headlines, such as the New York Times’ “Environment Rich in Germs May Reduce Risk of Asthma.”

The so-called “hygiene hypothesis” tries to explain supposedly higher rates of allergic responses — such as asthma — among “cleaner,” affluent nations as compared to rates in “less clean,” poorer nations. The idea is that greater childhood exposure to germs leads to fewer subsequent allergies.

Based on this notion, the editorial describes the “introductions of indoor plumbing in the 19th century, antibiotics in the middle of the 20th century, and the cleaner more energy-efficient homes at the end of the 20th century” as possible culprits of the supposed “epidemic” of allergies in developed societies.

But let’s look closer at the alleged “epidemic” of childhood asthma before reverting to outhouses, bloodletting and log cabins.

The Centers for Disease Control and Prevention recently reported the prevalence of childhood asthma increased 86 percent from 1980 to 1996 (from about 37 cases to 69 cases per 1,000 children).

At face value, the statistics seem to validate the existence of an epidemic. A more detailed examination, however, exposes the folly of such superficial analysis.

The CDC data were collected by researchers who conducted telephone surveys merely asking, “During the past 12 months, did your child have asthma?”

But asthma is a complex medical condition that survey respondents weren’t qualified to diagnose. There was no medical confirmation for the claimed cases of asthma. So the data can’t be viewed as reliable.

You don’t have to take my word for it, though. Even the CDC lost confidence in its line of questioning.

In 1997, the CDC altered the survey to ask, “Has a doctor or other health professional ever told you that your child had asthma?” and “During the past 12 months, has your child had an episode of asthma or an asthma attack?”

Since the new survey questions, the reported prevalence of asthma has leveled off.

An explanation for the reported rise in childhood asthma from 1980 to 1996 lies in the fine print of the CDC’s report.

The CDC says the asthma prevalence data are subject to the phenomenon of “diagnostic transfer” — essentially misdiagnosing bronchitis as asthma.

The CDC researchers said reports of asthma increases are mirrored by reports of decreases in bronchitis, bronchiolotis and pneumonia. “These patterns suggest that diagnostic transfer has contributed to the increasing trend in asthma health care utilization,” they acknowledged.

Since it’s not clear there’s been any epidemic of childhood asthma — or any other allergic condition for that matter — it’s not clear a “hygiene hypothesis” is needed to explain anything.

The origin of the hygiene hypothesis — i.e., apparent differences in disease rates between first-and third-world populations — reminds me of the myth about a high fiber diet reducing the risk of colon cancer.

A British medical missionary observed in the 1970s that African populations seemed to have less colon cancer than Western populations. He attributed this difference — casually, and not in any scientific way — to higher fiber African diets.

The intuitive appeal of the alleged dietary fiber-colon cancer connection helped institutionalize the unproven idea in our society. Now cereal companies are allowed to advertise that high fiber cereals “may reduce the risk of certain cancers.”

Thirty years after the birth of the hypothesis, however, research has yet to confirm that high fiber diets reduce colon cancer risk.

The hygiene hypothesis could very well belong in the same scrap heap. Its major underpinning — the reputed childhood asthma epidemic — almost certainly belongs there.

Steven Milloy is the publisher of , an adjunct scholar at the Cato Institute and the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).

4 thoughts on “Report: 33% of adults recently diagnosed with asthma do not have it”

  1. The concept of nocebo effect is critical. When someone with authority like a lawyer, doctor or witch doctor says something bad or evil (you have a condition, especially caused by others like smog, toxic food, breast implants, pin in a doll, etc.) you can have real symptoms.

    When we then reward the symptoms with disability, lawsuits, special benefits, etc. the symptoms become even more real.

  2. Ernest,

    Spot on, but the problem with the “diseases” you list is that they are all “diagnosed” by setting an arbitrary boundary on a continuous variable. Set a level for “normal” blood glucose and – hey presto – anyone over that has diabetes. Even better, have an expert panel reduce the “normal” level and suddenly you have a massive increase in incidence and you can scream EPIDEMIC! Nobody cares that the expert panel have a vested interest in seeing their speciality suddenly become the disease du jour or that there is a drug on the market that just happens to reduce the level of whatever.

    Over-diagnosis is probably the biggest single problem in health care – increasing costs and reducing the well-being of the general population with no impact on actual health. By the time you are in your 50’s pretty much everyone will have one of these parameters (blood pressure, blood glucose, cholesterol, BMI) outside the supposed normal level and be on some kind of chronic medication – making people feel ill and reducing their quality of life irrespective of any clinical symptoms. This is shameful and it goes across the entire health care industry in all developed countries.

  3. No surprise here. After over 30 years of medical practice, I can confidently estimate that more than 90% of people diagnosed as suffering from “Type II diabetes” do in fact have no disease at all. I would guess that well over 50% of people taking medication for hypertension also have a bogus diagnosis. More than 99% diagnosed with hypercholesterolemia or hyperlipidemia are likewise overdiagnosed. The great thing about defining “diseases” based on laboratory numbers is that one can simply lower the “normal” level arbitrarily and thus create a huge increase in “patients” out of the normal population.

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