### What you need to know
Asthma is characterised by recurrent episodes of cough and wheeze and difficulty in breathing. It affects more than 10% of children in the UK,1 but no universally agreed definition or diagnostic test exists for asthma in children or adults.2 Diagnosis in children mostly relies on a suggestive history and response to a trial of preventer treatment. Lack of objectivity in diagnosing asthma leads to both overdiagnosis and underdiagnosis.34 Clinicians and researchers have explored the role of objective tests, such as spirometry, peak flow variability, and exhaled nitric oxide in diagnosing asthma, and despite the lack of evidence, several organisations have incorporated these objective tests into diagnostic algorithms. But how helpful are these objective tests and algorithms?
This review:
This review focuses on algorithms from four recent and commonly cited guidelines: European Respiratory Society (ERS), British Thoracic Society/Scottish Intercollegiate Guideli