Overcoming asthma diagnosis challenges

In the absence of a single test used to diagnose asthma, doctors need to have a holistic picture of either a child or adult suspected to have the condition. 

We look at how asthma is diagnosed in children and adults.

There are some general questions a doctor may ask any patient suspected of having asthma, including around a family history of asthma, eczema or hay fever – which often occur together with asthma – and around your symptoms and the patterns they follow. There are also a host of tests that can aid in diagnosing asthma. Yet, making a confident diagnosis of asthma in children aged five and below may be challenging, says Dr Gabaza Tiva, a paediatric pulmonologist at Mediclinic Limpopo.

The difficulties of diagnosing asthma in children under five

“This difficulty is because episodic respiratory symptoms such as wheezing and cough are also common in children without asthma, particularly in those below the age of two,” Dr Tiva explains. “It’s also not possible to routinely assess airflow limitation or bronchodilator responsiveness in this age group by using the lung function tests available to test for airflow limitation and responsiveness to the medication.”

That is why a more holistic picture is needed. “A probability-based approach, looking at the pattern of symptoms during and between viral respiratory infections, may be helpful for discussion with parents or caregivers,” says Dr Tiva. “This allows individual decisions to be made about whether to give a trial of controller treatment.”

Controller treatment involves administering medication that reduces lung inflammation, which in the long term helps prevent asthma symptoms. Monitoring the effects of this trial can help with asthma diagnosis. Yet Dr Tiva stresses the importance of making decisions tailored to each individual child to avoid over or undertreatment.

Oscillometry testing, which measures blockages to air flow in the lungs and overall lung function, can be useful to check lung function in young children. The patient breathes normally through a tube connected to a computer so does not need to follow difficult instructions. Allergy testing and imaging may be useful in young children too.

“Ultimately, asthma diagnosis in children mostly relies on a suggestive history and response to a trial of controller treatment,” Dr Tiva says. “The lack of objectivity in diagnosing asthma in young children can, however, lead to both over and underdiagnosing.”

How asthma is diagnosed in older kids and adults

In children between six and 11 years old as well as adolescents, a history of typical variable respiratory symptoms can be a useful diagnostic tool. This examines symptoms of wheezing, shortness of breath, chest tightness and/or a cough, says Dr Tiva.

In asthma patients, these symptoms:

• occur variably over time and vary in intensity,
• are often worse at night or on waking up,
• are often triggered by exercise, laughter, allergens, cold air, and
• often appear or worsen with viral infections.

In children over five, adolescents and adults, the primary test used to diagnose asthma is a lung function test, which is done through spirometry. Through making patients blow through a tube as hard as possible for a few seconds, spirometry measures air flowing in and out of the lungs to give a measure of how well your lungs work. It documents your variable expiratory airflow limitation – a variation of airflow that is outside the normal range for healthy individuals of the same age.

Other tests to diagnose asthma are also available:

• Bronchial provocation tests also use spirometry but are used to measure how sensitive the airways in your lungs are. A spirometry breathing test is done before and after you inhale a mist.
• Allergy tests either through testing the skin or blood, while not able to diagnose asthma, can determine whether you have allergies that may be triggering asthma.  
• Imaging generally involves chest x-rays and CT chest scans. “While imaging is not routinely used in the diagnosis of asthma,” says Dr Tiva, “it may be useful to investigate the possibility of comorbid conditions or to make an alternative diagnosis.”
• An exhaled nitric oxide test measures the amount of nitric oxide exhaled from a breath. Higher levels are associated with the swelling of lung airways.
• A peak flow expiratory test involves blowing as hard as you can into a small handheld device called a peak flow meter. This measures how quickly you can blow air out of your lungs.

Keeping an asthma diary

Asthma management is much easier when the patient keeps a record of their symptoms. “When older patients are diagnosed with asthma, they are provided with an asthma diary and an asthma action plan,” Dr Tiva explains. Here, the timing, intensity and length of symptoms are recorded as well as the environment in which they happen.

“Asthma diaries help both the patients and the doctor to identify triggers, understand symptoms, and assess the effectiveness of their medication,” the doctor continues. “When they are used in conjunction with an asthma action plan, the diary can help patients recognise changes in their symptoms and take appropriate action to manage them.”