SUO child with inhaler getty images 3×2
‘Asthma: millions wrongly diagnosed,’ read the headline in the Daily Telegraph. ‘GPs warned that too many children are told they have disease without proper tests,’ the article went on.
It was the latest in a long line of articles critical of GPs this year, with respiratory experts claiming asthma diagnosis has become ‘trivialised’ and inhalers are now a ‘fashion accessory’.
The accusation that GPs are overdiagnosing asthma in part prompted NICE to recommend GPs use a new battery of tests to diagnose the condition, but there is anger in the profession over the repeated charges.
As RCGP chair Dr Maureen Baker pointed out in response to the Telegraph headline: ‘No single test can definitively diagnose asthma, and this can make it difficult to do in primary care.’
The Telegraph headline was based on Dutch research published in the BJGP that concluded 53% of children with asthma were incorrectly diagnosed.1
The researchers looked at the records of 656 children and only considered those with a confirmation of spirometry or a medical history highly suggestive of asthma to have the disease.
The guideline could lead to a sharp rise in referrals for diagnosis
Dr Duncan Keeley
Children who didn’t have a record of inhalation medication or an exacerbation were considered to not have asthma and were classed as ‘overdiagnosed’.
In April, an opinion piece in the Archives of Disease in Childhood by Professor Andy Bush, a consultant paediatric chest physician at the Royal Brompton and Harefield, and Dr Louise Fleming, a clinical senior lecturer in respiratory paediatrics at Imperial College London, claimed children still die because of failures in basic management of the condition.2
The authors said: ‘We propose that one contributing factor is that the diagnosis of asthma has been trivialised and inhalers are dispensed for no good reason, and have become almost a fashion accessory.’
They argued that symptoms – such as a cough – are being used to make an asthma diagnosis and this is leading to overdiagnosis, citing an Australian study of a group of children with a chronic cough, which found only 5% had a confirmed diagnosis of asthma by the end of the study.3
NICE’s intervention in January 2015 remains the most powerful, however. It reviewed a number of international studies on asthma patients, and concluding ‘that up to 30% do not have clear evidence of asthma’ – equating to around 1 million patients in the UK.
Draft guidelines published at the same time claim that diagnosing patients based only on symptoms has a moderate to low sensitivity and specificity.4
They recommend objective testing for asthma, advising GPs to perform a range of assessments – including FeNO and spirometry as first-line investigations in adults and children over five – completely bypassing the option to offer a trial of therapy as a means to diagnose asthma, as advocated by British Thoracic Society/Scottish Intercollegiate Guidelines Network (BTS/SIGN) guidelines.5 The NICE guidelines also say that a FeNO test should be offered if diagnosis is being considered in anyone over 16 who has normal spirometry, or obstructive spirometry but negative reversibility.
GP respiratory experts at the time warned that the guidelines had ‘huge implications’ and that it could be ‘dangerous’ to claim that many people diagnosed with asthma may not have it.
NICE went some way to acknowledging this. Despite recommending spirometry as first line, the draft guidance admits: ‘Spirometry is only useful if a good quality spirogram is obtained that is both accurate and reproducible, which will require training of personnel.’
But such was the weight of criticism that greeted the draft, NICE took the unprecedented step last year of delaying the full guidelines to allow them to be piloted at seven primary care sites until October this year. The final guideline is likely to be published early next year.
The whole row has incensed GP respiratory experts, who have pointed out that asthma is a variable condition and there may be as many cases missed as there are diagnosed.
Dr Mark Levy, respiratory lead at NHS Harrow CCG and a GP in north London, says: ‘We don’t have enough data. Asthma may be overdiagnosed, but it may also be underdiagnosed.’
Dr Levy dismisses NICE’s recommendation to use spirometry to diagnose asthma as ‘ill thought-out’ and impractical: ‘If spirometry is done when the person is bronchodilated, what is the GP supposed to do? Daily spirometry until variable airflow obstruction is demonstrated? I don’t think so.’
Dr Duncan Keeley, Oxfordshire GP and member of the Primary Care Respiratory Society, expressed concern at the validity of using international diagnosis data to justify a change in UK practice.
He says: ‘There are not enough recent studies based in the UK to fully assess the extent of this. NICE based some of its guideline on an Australian study from 10 years ago, but this has limited relevance to the UK and it would be interesting to know what research conducted in a UK setting would find.’
Dr Keeley adds that the NICE guidance – if approved – will increase referrals, putting pressure on the health service at a time when it least needs it.
He explains: ‘Few primary care practices have the ability to do FeNO measurements, and there are issues with how spirometry is measured in that not everyone is using the same standard.
‘Added to this are problems with access to such measurements in primary care – there’s a possibility that the guidelines would lead to a sharp increase in referrals for diagnosis.’
In addition to the criticism, the BTS/SIGN guideline – long considered the ‘gold standard’ – has been recently updated and its approach contrasts sharply with that of NICE.
It says GPs’ current approach is the right one and recommends that a carefully monitored trial of treatment – typically six weeks of inhaled corticosteroids – should be used to guide diagnosis in any patient suspected to have a high probability of asthma.
Objective tests – such as spirometry, FeNO and bronchial challenge – are included within the BTS/SIGN guideline, but unlike the NICE draft, are not advised for diagnostic purposes unless a patient has failed a therapy trial or only has an ‘intermediate probability’ of asthma.
BTS/SIGN guideline adviser Dr Hilary Pinnock, a GP and a reader at the Centre for Population Health Sciences at the University of Edinburgh, says the guidance takes a more ‘pragmatic approach’ to asthma diagnosis than NICE.
Dr Pinnock adds: ‘The important message is that asthma as a condition is very variable. No investigations are absolute and there is no gold standard, but the BTS/SIGN guideline tried to take a more pragmatic approach, although its thoughts echo that in the NICE guidance.
‘It’s important to recognise the difficulties of asthma diagnosis and that it isn’t as simple as one test.’
The overall situation is confusing for GPs. With NICE currently gathering evidence to support its draft guidance via its pilots, GPs could have two potentially conflicting sets of advice, at the same time as facing criticism for their current management of asthma.
The profession cannot yet breathe a sigh of relief.
How the two sets of guidelines on asthma diagnosis differ
NICE: diagnosis and monitoring of asthma – draft guidance4
For all patients over five, GPs should perform objective tests (including spirometry and FeNO) at presentation, or once acute symptoms have been controlled.
Do not make a formal diagnosis of asthma until objective tests have been done.
Offer a FeNO test if a diagnosis of asthma is being considered in anyone over 16, or in children over five if they have normal spirometry, or obstructive spirometry, but negative bronchodilator reversibility.
A bronchial challenge test with histamine or methacholine can be offered in adults and young people older than 16 if there is diagnostic uncertainty after a normal spirometry and either a FeNO level of ≥40ppb and no variability in peak flow readings or a FeNO level of ≤39ppb with variability in peak flow readings.
GPs should use the initial structured clinical assessment to estimate the probability of asthma
For patients with a high probability, record ‘suspected asthma’ and start a carefully monitored trial (typically six weeks of inhaled corticosteroids). A good response based on symptom questionnaire findings and/or lung function tests – either FEV1 or home serial PEF – confirms the diagnosis
Patients with intermediate probability – either on initial assessment or after a failed trial – should undergo spirometry and, if positive, reversibility tests and/or a trial of therapy. If spirometry is normal, they should undergo bronchial challenge tests and/or FeNO.
In patients with low probability of asthma, investigate alternative diagnoses and/or refer for further tests.
1 Looijmans-van den Akke I, van Luijn K, Verheij T. Overdiagnosis of asthma in children in primary care: a retrospective analysis. BJGP. Online Feb 2016
2 Bush A, Fleming L. Is asthma overdiagnosed? Arch Dis Child online Apr 2016
3 Marchant J, Masters I, et al. Evaluation and outcome of young children with chronic cough. Chest 2006;129:1132–41
4 NICE. Diagnosis and monitoring of asthma in adults, children and young people. Draft guideline. 2016
5 BTS/SIGN. British Guideline on the Management of Asthma, 2014