How can I differentiate between allergic and non-allergic asthma in a patient presenting with wheezing?

To differentiate between allergic and non-allergic asthma in a patient presenting with wheezing, a combination of clinical history and specific objective tests is used ¹.

Clinical History:

A structured clinical history is essential ¹. Key aspects to check include:

• Any triggers that worsen symptoms ¹.
• A personal or family history of asthma or allergic rhinitis ¹.

Objective Tests:

If asthma is suspected but not confirmed by initial objective tests such as fractional exhaled nitric oxide (FeNO), bronchodilator reversibility (BDR), or peak expiratory flow (PEF) variability, further investigations for allergic sensitisation should be performed ¹. These include:

• Skin prick testing: Specifically, testing for sensitisation to house dust mite is recommended ¹.
• Blood tests: Measure total IgE level and blood eosinophil count ¹.

A diagnosis of asthma can be made if there is evidence of sensitisation (for example, to house dust mite on skin prick testing) or a raised total IgE level, in conjunction with an eosinophil count greater than 0.5 x 10^9 per litre ¹. Conversely, asthma can be excluded if there is no evidence of sensitisation to house dust mite on skin prick testing or if the total serum IgE is not raised ¹.