Spirometry should be used as the first-line investigation for diagnosing asthma in children over 5 and adults, says National Institute for Health and Care Excellence (NICE).
The draft guideline – NICE’s first on asthma – reinforces recommendations made in the 2014 BTS/SIGN asthma guideline which also supports spirometry as the preferred initial test to assess the presence and severity of airflow obstruction.
Currently, there is no gold standard test available to diagnose asthma and it is diagnosed principally on the basis of a thorough history taken by an experienced clinician.
In the UK, 4.1 million people receive treatment for asthma. However, studies of adults diagnosed with asthma suggest that up to 30 per cent do not have clear evidence of asthma. Some may have had asthma in the past, but it is likely that many have been given an incorrect diagnosis.
This latest guideline aims to determine the most clinical and cost effective way to effectively diagnose people with asthma and determine the most effective monitoring strategy to ensure optimum asthma control.
The guideline stresses that to achieve an accurate diagnosis clinical tests should be used as well as checking for signs and symptoms. The process which the healthcare professional should follow in the initial assessment, and the tests to use, are presented in simple flow charts.
The draft guideline recommends spirometry as the first-line investigation for asthma in adults older than 16 and children aged 5-16 years. Healthcare professionals should regard a forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio of less than 70% as a positive test for obstructive airway disease.
Further breath tests should be carried out depending on the results from spirometry and the patient’s age.
For adults and young people over 5 years, healthcare professionals may need to check for levels of nitric oxide, a gas which is found in larger volumes in people with asthma, using the fractional exhaled nitric oxide (FeNO) test, and carry out a bronchodilator reversibility (BDR) test.
The treatment of under-5s should be based on professional judgement and observation until the child is old enough to take clinical tests.
Professor Mark Baker, director of clinical practice at NICE said: "Asthma is a long-term incurable condition that affects millions of people of all ages. If left untreated asthma attacks can be life threatening.
"However, with appropriate treatment and thoughtful monitoring, most people will be able to successfully control their symptoms and be spared from serious harm."