The British Thoracic Society/SIGN guidelines (2016) on asthma management said that there are no consistent gold-standard diagnostic criteria for asthma, meaning “it is not possible to make unequivocal evidence-based recommendations on how to make a diagnosis of asthma.”3

Since then, the NICE guideline on the diagnosis and monitoring of asthma, and management of chronic asthma (NG80 – November 2017), said that diagnosis should not rely solely on symptoms, nor on a history of atopic disorders alone. It advises that diagnosis should include one or more objective tests, depending on age and outcomes.2

Among the objective testing methods NG80 proposes are:

·       airway inflammation measures by measuring fractional exhaled nitric oxide (FeNO);

·       lung function tests such as spirometry, bronchodilator reversibility, or peak expiratory flow variability;

·       airway hyperreactivity measures, such as direct bronchiole challenge using histamine or methacholine.

Tests which NICE says should not be used to diagnose asthma are:

·       skin prick tests to aeroallergens;

·       serum total and specific IgE;

·       peripheral blood eosinophil count;

·       exercise challenge (for adults).

However, it says skin prick tests and specific IgE tests can be used to identify triggers after a formal asthma diagnosis has been made.