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.
Professor Dominick Shaw, professor of respiratory medicine at the University of Nottingham said the recommendations recognised the struggle to balance a population-based or
personalised approach to diagnosis that had led to conflicting guidelines in the past with BTS, NICE and GINA, but did not really solve that problem.
“This gives you another another algorithm to consider,” he said. “The positive thing in the guidelines that we don’t do well at the moment is we don't do bronchial challenge tests
routinely in secondary care and its not standardised.”
He added that the higher cut off for FEV 1 /FVC was interesting but that COVID had had a big impact on the availability of spirometry in primary care.
“FeNO is used in some practices. Peak flow variability is difficult to calculate,” he added.
“These guidelines are a valiant attempt to try to simplify the situation we find ourselves in, but may add to some confusion. It’s interesting but its only any good if you're then set up to be able to do all the other tests.”
Professor Shaw welcomed the emphasis in the recommendations on having a one-visit diagnostic pathway.
“That fits with the current move to have diagnostic hubs.”