Michael Joyce is a multimedia producer and writer with HealthNewsReview.org. He tweets as @mlmjoyce.
As many as 1 in 3 adults diagnosed with asthma may not actually have the disease, according to new research published in the Journal of the American Medical Association (JAMA).
Canadian researchers evaluated 613 patients with physician-diagnosed asthma and found that 203 participants (33%) most likely did not have the disease. After an additional 12 months of follow-up of this latter group, 181 subjects (30%) continued to exhibit no clinical or laboratory evidence of asthma.
This study, and its accompanying editorials, hit on a theme we’ve often raised with regard to cancer and many other chronic diseases: overdiagnosis leading to overtreatment. But it also raises the specter of misdiagnosis from the get-go, which can lead to erroneously treating a condition that isn’t there.
The Canadian results may also confuse many of us who have grown accustomed to news stories warning us that asthma is on the rise. So which is it? More asthma which needs more aggressive treatment or less asthma warning against overtreatment?
“I think asthma is both overdiagnosed and underdiagnosed,” says Dr. Nancy Ott, an allergy and immunology specialist in practice for 28 years. “We don’t have a specific test that is definitive for asthma, and the diagnosis is nuanced. You need to look at the symptoms, the patient’s history, their family history, and the objective tests collectively. And I think we need to be much more strict in what constitutes asthma because the symptoms alone overlap with so many other conditions.”
This is not a message we hear nearly enough in news stories: the diagnosis of asthma, although common, is anything but cut-and-dried. In outpatient clinics – where most asthma is diagnosed – time pressures can lead to incomplete evaluations, which lead to misdiagnoses (which, by the way, includes over-, under-, and no diagnoses), and this can ultimately lead to patients suffering physically, emotionally and financially.
Dr. Ott said such an outpatient scenario is not uncommon: busy physicians will evaluate patients who come in with classic asthma symptoms – such as bouts of shortness of breath, wheezing, coughing and chest tightness – and they’ll simply try them on an inhaler to see if they improve. If they do, they will often get labeled as asthmatic – or, ‘rule-out’ asthma – even though objective tests were not ordered.
A roundup of the extensive news coverage of the Canadian study shows that several outlets covered the story thoughtfully. The Vancouver Sun focused strongly on the role both misdiagnosis and remission (asthma can have a waxing and waning course) may have had on the study:
“We think that a large proportion of them had been misdiagnosed in the first place and another proportion that (was) a bit smaller had actually gone into remission, their asthma was no longer active,” said principal investigator Dr. Shawn Aaron, head of respirology at the University of Ottawa.
Medical textbooks say about six per cent of people with asthma go into remission over a 10-year period, said Aaron. “But we found at least 20 per cent had gone into remission.”
However, “one of the main messages I want to get across is that some people are being misdiagnosed because they’re not being properly investigated to begin with,” he said from Ottawa.
Which brings up an important point: the symptoms of asthma overlap with several other diseases. In the Canadian study, 12 people, or 2 percent of the participants, had serious conditions other than asthma, like heart disease and pulmonary hypertension. Others had problems such as hyperventilation from panic attacks, and gastroesophageal reflux (GERD). These latter two conditions frequently mimic asthma. As does vocal cord dysfunction. Suffice to say that if you were to take each of the classic symptoms of asthma individually, the list of diseases associated with that symptom is well over a dozen.
Reuters did well to highlight two limitations of the study … remission as noted above, and the severity of the asthma:
One limitation of the study is that researchers only followed patients for a total of 15 months, which isn’t long enough to rule out the possibility that some patients in remission might have asthma symptoms in the future, the authors note. The study also excluded patients using long-term oral corticosteroids, leaving only people with milder forms of asthma to participated.
Furthermore, only 45 percent of the subjects were on daily asthma medications, which also suggests a potential bias toward milder cases dominating the study. The researchers point out another possible limitation of the study is the sensitivity of bronchial challenge tests to detect asthma is 98 percent, but not 100 percent. The test can be falsely positive in smokers or those with allergies.
Furthermore, results from objective lung testing to confirm asthma at the time of diagnosis were not available for many of the study participants. Therefore, they could have had a misdiagnosis or been in remission when they were first labeled as asthmatic.
In an editorial accompanying the JAMA article, two pulmonologists from Boston had this to say about the study:
“These results provide 2 important insights that inform clinical management. First, patients who have been diagnosed with adult-onset asthma may not continue to have asthma or to require asthma treatment indefinitely. Second, physiological testing, such as spirometry before and after bronchodilator administration, is an essential component of the diagnosis of asthma to avoid unnecessary treatment or an incorrect diagnosis. During the past decade there has been increasing concern that at times patients are exposed to too many medications; although these results suggest that some patients can safely reduce their asthma medications, they also support more frequent use of physiological testing to guide asthma management.”
Drs. Hollingsworth and O’Connor go on to say that managing chronic diseases like asthma is complicated, time-consuming and requires a special kind of vigilance:
It would not be surprising that a previously diagnosed chronic health condition like asthma, that is not currently bothersome, would be quickly classified as well controlled, with an equally quick decision to continue current treatment. But, could this efficiency lead to over-treatment in the case of a chronic health condition that might resolve over time or might not have been accurately diagnosed in the first place? The study by Aaron and colleagues is an important reminder that in addition to reviewing asthma symptoms and treatment, trying to understand if the diagnosis of asthma is still appropriate is an important part of clinical care.
In a way, the diagnosis and management of asthma – like cancer – holds a mirror up to our healthcare system (and health journalism). Although the disease is common, the diagnosis is not as commonplace as messages in the media will often have us believe. It’s nuanced, not a nice and neat binary that’s easy to treat and easy to write about. Which means, for the doctors who deal with asthma, there should be a premium placed on taking their time, being thorough, and constantly reassessing. The same should hold true for those of us who write about it.