New European Respiratory Society guidelines conclude that spirometry should be the first test done in all adults with symptoms suggestive of asthma and sets a FEV1 /FVC threshold
less than 75%.
The cut off is higher than the more commonly used 70% say the guidelines but also note that over-diagnosis happens in around 30% of patients in primary care partly because
spirometry is not done in the first place.
Bronchial challenge testing should also be used in secondary care to confirm a diagnosis of asthma when it had not been established in primary care, the guidelines recommend.
An algorithm for diagnosis sets out the order of several tests in diagnosis including fractional exhaled nitric oxide (FeNO) and peak flow variability (PEF) when spirometry does not
produce a clear answer.
Writing in the European Respiratory Journal, the guideline taskforce said the recommendations “emphasise the need to establish a correct diagnosis of asthma in patients with suggestive symptoms and reinforce performing spirometry on a much larger scale than is currently undertaken in primary care”.
They conclude: “Whether measuring FeNO or monitoring PEF should be implemented in primary care, in the absence of significant bronchodilator reversibility, depends on the
availability and access to bronchial challenge.”
The taskforce, who were set up in 2018 to address the question of diagnosis of asthma, said one of the issues they came across when trying to produce a “pragmatic” guideline for
clinicians on the best strategy was the paucity of well-designed studies.
Growing recognition of the heterogeneity and complexity of asthma, and evidence that it is possible to further categorise patients into distinct groups with differing responses to
treatment may lead to a more “nuanced and individualised diagnostic approach” in the near future, the taskforce concluded.