Asthma Not Confirmed in Many Previously Diagnosed Adults

Veronica Hackethal, MD

January 18, 2017

In a substantial number of adults with physician-diagnosed asthma, asthma was not confirmed on revaluation, according to a Canadian study published in the January 17 issue of JAMA.

"Among adults with physician-diagnosed asthma, a current diagnosis of asthma could not be established in 33.1% who were not using daily asthma medications or had medications weaned. In patients such as these, reassessing the asthma diagnosis may be warranted," Shawn Aaron, MD, from the Ottawa Hospital Research Institute, University of Ottawa, Ontario, Canada, and colleagues write.

These patients may have experienced spontaneous remission or may have been misdiagnosed, the authors speculate.

Current guidelines recommend diagnosing asthma by testing for reversible airflow limitation and confirming positive results by testing expiratory airflow. However, the variable presentation of the disorder and its relapsing and remitting course can complicate diagnosis and may lead many physicians in the community to diagnose and treat asthma empirically.

The study included 701 adults randomly sampled and screened via telephone in Canada's 10 largest metropolitan areas who had self-reported having physician-diagnosed asthma within the last 5 years. Researchers used information from treating physicians to confirm how diagnoses were first made.

Researchers then confirmed or ruled out asthma with serial monitoring of symptoms, home peak flow, spirometry (a measure of lung function), and confirmatory bronchial challenge tests.

Participants with negative tests had their medications tapered off, using a predefined protocol, and were followed with repeat bronchial challenge tests for 1 year.

A study pulmonologist evaluated patients and confirmed asthma or assigned alternative diagnoses when necessary.

The analysis included 613 patients (mean age, 51 years; 67% women) who completed the study.

The study ruled out asthma in 203 participants (33.1%; 95% confidence interval [CI], 29.4% - 36.8%). Most participants had benign alternative diagnoses; however, 12 (2.0%) had serious cardiorespiratory conditions that had been misdiagnosed as asthma.

Compared with those with confirmed asthma, those in whom asthma was ruled out were less likely to have received initial diagnoses using airflow limitation testing (43.8% vs 55.6%, respectively; absolute difference, 11.8%; 95% CI, 2.1% - 21.5%).

Information from physicians on initial diagnoses was available for 530 of the patients, of whom 269 (50.8%) had had confirmatory airflow limitation testing. The remainder received their diagnoses on the basis of symptoms and/or physical exam findings.

More than 90% of participants whose asthma was ruled out safely stopped asthma medication for 1 year. Of these, 181 participants (29.5%; 95% CI, 25.9% - 33.1%) still had no clinical or laboratory evidence of asthma.

The authors suggest two possible explanations for these results: participants may have experienced spontaneous remission of asthma, or they may have been misdiagnosed.

The authors also point out that 35.0% of patients in whom asthma was ruled out were using daily asthma medications, which would have done them no good. It would also have exposed them unnecessarily to adverse medication effects and increased cost, the authors say.

"These results provide 2 important insights that inform clinical management," write Helen Hollingsworth, MD, and George O'Connor, MD, both from Boston University School of Medicine in Massachusetts, in an accompanying editorial. Dr O'Connor is also associate editor of JAMA.

First, adult asthma may not become chronic and may not require indefinite treatment in some patients. Second, expiratory airflow testing is "essential" for asthma diagnosis to avoid misdiagnosis and unnecessary treatment.

"[A]lthough 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," they write.

They also note that the findings may not generalize across the range of asthma severity. The study excluded people receiving long-term oral corticosteroids, and just 45% of participants used daily asthma medications; therefore, the study may have excluded many people with moderate to severe asthma.

Nevertheless, the editorialists conclude, "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."

One or more authors reports honoraria and other fees, advisory board or other membership, grants, and/or consulting for one or more of the following: Boehringer Ingelheim Canada, GlaxoSmithKline, Teva, AstraZeneca, Methapharm, Canadian Thoracic Society, Novartis, Synertec, Grifols, Roche, Actelion, Bayer, CSL Behring, Prometic.Altair, Amgen, Asmacure, Boston Scientific, Genentech, Ono Pharma, Schering, Wyeth, Merck, Global Initiative for Asthma, and/or Laval University. Dr O'Connor reports consulting for AstraZeneca and grants from Janssen Pharmaceuticals and the National Institutes of Health. Dr Hollingsworth has disclosed no relevant financial relationships.

JAMA. 2017;317(3):262-263, 269-279. Article abstract, Editorial extract

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