A draft guideline released by NICE suggests spirometry should be used as ‘the first-line investigation’ for diagnosing asthma in adults over 16 and children over 5 years old.

More than four million people in the UK currently receive asthma treatment, but studies of those diagnosed now show that up to 30% may not in fact be asthmatic. While some may have suffered from asthma in previous years, many are likely to have been wrongly diagnosed in the first place.

Spirometry, which measures airflow obstruction, is one of several diagnosis methods currently used, but with no recommended standard method currently in place, asthma is principally diagnosed through a patient history taken by experienced clinicians.

NICE’s guideline – its first regarding asthma diagnosis – proposes that, for greater accuracy, clinical tests should be applied alongside checking for signs and symptoms. Easy-to-follow flow charts outline the clinician’s initial assessment process and the tests to be used.

Professor Mark Baker, director of clinical practice at NICE said: "Our aim with this guideline is to give clarity and set out the most clinical and cost-effective ways to diagnose and monitor asthma based on the best available evidence."