NICE released guidance on the management of asthma in 2017. These followed on quickly from the 2016 British Thoracic Society (BTS) guidelines. Given previous precedents where specialist societies or Royal colleges eventually default/contribute to NICE, we have followed the NICE guidance for the notes and questions.
NICE guidance has radically changed how asthma should be diagnosed. It advocates moving anyway from subjective/clinical judgements are more towards objective tests.
There is particular emphasis on the use of fractional exhaled nitric oxide (FeNO). Nitric oxide is produced by 3 types of nitric oxide synthases (NOS). One of the types is inducible (iNOS) and levels tend to rise in inflammatory cells, particularly eosinophils. Levels of NO therefore typically correlate with levels of inflammation.
Other more established objective tests such as spirometry and peak flow variability are still important.
All patients >= 5 years should have objective tests. Once a child with suspected asthma reaches the age of 5 years objective tests should be performed to confirm the diagnosis.
Diagnostic testing
Patients >= 17 years
patients should be asked if their symptoms are better on days away from work/during holidays. If so, patients should be referred to a specialist as possible occupational asthma
all patients should have spirometry with a bronchodilator reversibility (BDR) test
all patients should have a FeNO test
Patients 5-16 years
all patients should have spirometry with a bronchodilator reversibility (BDR) test
a FeNO test should be requested if there is normal spirometry or obstructive spirometry with a negative bronchodilator reversibility (BDR) test
Patients < 5 years
- diagnosis should be made on clinical judgement
Specific points about the tests
FeNO
in adults level of >= 40 parts per billion (ppb) is considered positive
in children a level of >= 35 parts per billion (ppb) is considered positive
Spirometry
FEV1/FVC ratio less than 70% (or below the lower limit of normal if this value is available) is considered obstructive
Reversibility testing
in adults, a positive test is indicated by an improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
in children, a positive test is indicated by an improvement in FEV1 of 12% or more.
From: Dr. Ataullah.