Manchester researchers show guidelines for asthma diagnosis require improvement

The research, funded by NIHR Manchester BRC and Asthma + Lung UK, is part of the ongoing Rapid Access Diagnostics in Asthma (RADicA) study.

Results of this study (Asthma diagnosis: a comparison of established diagnostic guidelines in adults with respiratory symptoms) have been published recently in eClinical Medicine, part of The Lancet Discovery Science journals.

There are three sets of guidelines from around the world that are commonly used to diagnose asthma, from the European Respiratory Society (ERS), the UK’s National Institute for Health and Care Excellence (NICE) and the Global Initiative for Asthma (GINA).  These typically include tests of lung function and inflammation, often put together in the form of an algorithm.

Prof Simpson continued: “The three guidelines have been written by experts but were largely not tested at all before implementation.

“The aim of this study was therefore to evaluate the performance characteristics of the ERS, NICE, and GINA asthma diagnostic algorithms in adults with symptoms of asthma but not currently receiving treatment, through our RADicA clinic.”

Participants were referred between May 2019 and June 2022 mostly from GP practices across Manchester with suspected asthma and underwent extensive investigations at the NIHR Manchester Clinical Research Facility (CRF) at Wythenshawe Hospital.

As well as completing multiple tests, participants were seen by a respiratory specialist before being given an asthma preventer inhaler, then repeating the tests a few weeks later. This information was then reviewed by the expert panel of asthma specialists to determine whether they had asthma.

The Manchester researchers then assessed how well each individual test worked to identify or exclude asthma and used this information to see how well the published algorithms diagnosed asthma compared to each other and to their expert panel.

Of the 118 participants involved in this study, 53 (45 per cent) did not have asthma by any of the three measures, and only 21 (18 per cent) were always diagnosed with asthma by all three guidelines. The remaining 44 adults (37 per cent) would have been given a different diagnosis (“asthma” or “not asthma”) depending on which guideline was followed.

Prof Simpson added: “Getting an accurate early diagnosis of asthma is vital and what we were able to capture in the RADicA study were test results before people started on preventer treatment – as that could change the results of any tests. This was only possible because we worked closely with our local GPs, who referred in people with suspected asthma, before starting preventer treatment.

“Our research shows that considerable variability exists between the results of the diagnostic guidelines, because they include different tests, with different thresholds, and the order in which they are conducted is different too. The guidelines generally performed well to ‘rule in’ asthma but lacked sensitivity and so missed many cases of asthma that were diagnosed by other guidelines, and by our expert panel.

“These guidelines therefore need improvement to avoid misdiagnosis of this common long-term condition.”

Prof Simpson, along with Professor Stephen Fowler, Respiratory Medicine Theme Co-Lead and Professor Clare Murray, Asthma Programme Lead, run the Manchester BRC-funded RADicA study. To date, more than 400 patients have been recruited, of which 52 per cent are adults.

Assessments include a FeNO test, where people breathe into a machine that measures the level of nitric oxide in breath (a sign of inflammation in the lungs), spirometry, which measures how fast people can breathe out and how much air lungs can hold, as well as responsiveness to inhaled corticosteroid therapy (ICS) treatment.

Roxanna’s story – a RADicA study participant

Roxanna Caruana, 39, a GP from Didsbury, took part in the RADicA study after being referred by her own GP having experienced asthma-like symptoms on and off for several years.

She had previously not had a diagnosis of asthma, but after taking part in the study received confirmation in March earlier this year that she did have the condition.

The mum of three said: “My symptoms would definitely be worse throughout the winter, and early in the morning and later at night. Especially on cold mornings, I would feel pressure in my chest and would often get very short of breath just doing the school run. I would arrive wheezing and out of breath just from walking.

“For me, knowing is key and to have that confirmed asthma diagnosis and having started on steroid inhaler treatment over the summer means I hope I will get through winter with very little or no symptoms. This will make a great deal of difference to my quality of life.”

Roxanna, who is originally from Malta and moved to the UK when she was 25 said she really wanted to take part in the study when she was offered the chance. Her elder two children also took part in RADicA as healthy volunteers.

“The next steps are to develop a better algorithm from our results, and then to test it in adults.”

Professor Murray added: “Asthma diagnosis is just as big a problem in children and having recruited around 200 children from across Manchester to the RADicA study we are now looking forward to analysing this data and trying to improve asthma diagnosis for children too.”