An international team led by McMaster University researcher Wafa Hassan is urging clinicians to rely less on symptoms alone when diagnosing asthma, warning that missed and incorrect diagnoses remain common when objective testing is unavailable or delayed. The team’s review in The Lancet Respiratory Medicine says wider access to lung-function and airway-inflammation tests could help distinguish variable asthma from conditions that produce similar cough, wheeze or breathlessness.
Asthma can resemble infections, dysfunctional breathing and other airway disorders, while symptoms can disappear between appointments. The authors argue that history alone is often insufficient and that access to spirometry, bronchodilator testing and measures of airway inflammation remains uneven.
The review describes diagnosis as a sequence rather than a single test. Spirometry can show variable airflow obstruction, bronchodilator testing can document improvement after medication, and peak-flow monitoring can capture changes that are missed during a quiet clinic visit. Tests of airway responsiveness or inflammation may add evidence when standard spirometry is normal but the clinical suspicion remains high.
That distinction matters because both underdiagnosis and overdiagnosis have consequences. A missed diagnosis can leave a patient exposed to preventable attacks, while an incorrect label can lead to years of medication without addressing another cause of cough, wheeze or breathlessness. The authors place particular emphasis on repeating or combining tests when the first result does not match the history.
The recommendations arrive amid a wider push to reduce diagnostic error in a disease defined by variability. A patient may wheeze during a viral infection, exercise normally a week later and produce normal spirometry at an appointment. Conversely, reflux, inducible laryngeal obstruction, chronic cough syndromes and deconditioning can mimic part of the asthma picture.
The review argues that this uncertainty should trigger a planned process: test when possible, repeat testing when the disease is quiet, document response to bronchodilator treatment and reconsider competing explanations when control remains poor.
That approach could also improve research, because trials and quality programs depend on knowing that participants and patients actually have the condition being counted. The obstacle is not a lack of available tests so much as uneven access, training and follow-through. In settings without specialist equipment, the authors support pragmatic pathways, but they resist allowing pragmatism to become permanent reliance on symptoms alone.
For patients, the report is not a reason to distrust an asthma diagnosis. It is a reason to ask how it was confirmed, especially when treatment is not working as expected. Objective testing must still be interpreted by a clinician, and a normal result on one day does not automatically exclude variable disease.
Access is the weak link. Primary-care offices do not always have reliable spirometry, and referral pathways can be slow. Young children and people already taking inhaled corticosteroids may also be harder to test. The review therefore calls for health systems to improve diagnostic capacity while recognizing that no single result settles every case.
The immediate challenge is practical: objective asthma testing must become easier to obtain, not merely more strongly recommended. Until then, the authors’ call to action is likely to matter most when a diagnosis is uncertain, symptoms do not respond as expected or a patient has never had airflow limitation documented.
The development shifts the central question from whether symptoms sound like asthma to whether variable airway disease has been demonstrated. For clinicians, that means documenting the basis of the diagnosis and revisiting it when the course is atypical. For patients, it creates a clearer route forward when treatment and symptoms do not line up.
