Continuing our series, GP respiratory specialist Dr Andrew Whittamore debunks some common myths about asthma – and explains some less well-known facts
Myths
1. SABAs are harmless medicines
Many studies have shown that overuse of short-acting beta-agonists (SABAs) in asthma is associated with increased risks of exacerbation and all-cause mortality.1,2 This effect is dose-dependent, with the increased risks seen among those on 3 or more SABA inhalers per year. This corresponds to international consensus that having symptoms or using a SABA inhaler 3 or more times per week signifies poor asthma control, likely as a result of undertreated inflammation in the airways.3
Anyone with SABA overuse requires an assessment of their symptoms and triggers, and optimisation of preventer treatment – which should include optimising adherence, inhaler technique and considering stepping up the level or dose of preventer medication.
The new joint NICE, British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network (SIGN) guideline recommends prescribing anti-inflammatory reliever (AIR) therapy or maintenance and reliever therapy (MART) regimens to anyone overusing their SABA reliever, or people currently prescribed a SABA reliever inhaler only.4
2. Peak flow has no place in asthma diagnosis or management
The new NICE asthma diagnostic algorithm only recommends peak expiratory flow (PEF) measurement to diagnose asthma if spirometry or FeNO is not available or has significant waiting times.1 The guidance does not recommend its use as part of routine monitoring. There are a couple of caveats if you read closely, however:
- If someone is presenting with asthma symptoms, PEF or spirometry can be used with pre- and post-bronchodilator readings to make a diagnosis of asthma.
- On an asthma action plan, some patients can use PEF values to help them make decisions about their self-management.
In acute asthma management, which was included in the joint guideline but is covered in a related joint NICE/BTS/SIGN asthma pathway,5 measuring PEF is an essential part of assessing anyone with a flare-up of their asthma symptoms.6 PEF is one measure used to assess the severity of an exacerbation and help decision making about medication and escalation of care.
3. You need to wheeze to have asthma
Don’t be fooled by a lack of wheeze when examining someone with asthma.
Asthma is a variable condition so someone with asthma will not wheeze all of the time. Even in acute asthma, there may be no audible wheeze if someone has taken an effective dose of bronchodilator. In acute asthma, a silent chest with no wheeze is a life-threatening feature.
In addition, cough-variant asthma, where cough is the only symptom, is a recognised subgroup of asthma.7 Not wheezing is a common reason for asthma not being identified quickly.
4. Adults do not benefit from using a spacer
A spacer should be considered for everyone with a pressurized metered-dose inhaler (pMDI), but many patients and clinicians associate use of a spacer in children with asthma. Yet as many as 80% of adults do not use their inhalers correctly and even with optimal technique pMDIs deliver, at best, only around 20% of the emitted dose to the lower airways,8 leaving around 80% in the oropharynx.
Use of a spacer slows down the aerosolised particles emitted from the pMDI, which may further increase lung deposition. It significantly filters out and thereby reduces oropharyngeal deposition of the larger particles emitted from a pMDI, reducing side effects.
The correct use of a spacer also helps mitigate a common and potentially critical problem of poor coordination of activation of the pMDI. Although some coordination is still needed, the patient has a lot more time to accomplish this effectively.
Despite recommendations in national and international guidelines that pMDIs should be used with a spacer, they appear to be widely underused; one study found only about 10% of patients with pMDIs in the UK were using a spacer.8
5. You can tell whether an inhaler is empty by shaking it
Without a dose counter it can be very hard for patients to know when their inhaler may be empty.9,10 As well as the active medication in a pMDI, there is also propellant. When an empty pMDI is shaken, you can still hear the propellant inside the canister. This can lead to both underuse and overuse. Underused inhalers create waste as unused medication is disposed of. Overused inhalers create risk of harm as the patient will not be receiving any active medication when using their inhaler. Patients should be prescribed inhalers with dose counters where possible, or encouraged to keep a log of doses used – this should be easy for patients taking regular preventer doses and occasional or rare reliever doses.
Facts
1. A single test can be enough to confirm a diagnosis of asthma
All objective tests for asthma generally have reasonable specificity (where a positive test can be trusted to rule asthma in). However, they have low sensitivity (a negative result is unreliable in excluding asthma).
A novel approach within the new NICE guidelines uses a high threshold for tests such as eosinophil count and FeNO, to increase the specificity further.11 Coupled with a clear clinical history, a single positive test can be used to confirm a diagnosis of asthma. However, a negative test does not exclude asthma, and further tests should be performed.
New tests are still needed to help improve the accuracy of asthma diagnosis. It is estimated that as many as 30% of people with an asthma diagnosis may not have the condition.12
2. FeNO is an important part of monitoring asthma
The NICE joint guidelines recommend using FeNO to routinely monitor asthma, especially before and after changing treatment.11 While many GP practices currently do not have access to a FeNO device, the guidelines endorsement should now ensure they are made widely available, given the approach has been shown to reduce severe exacerbations in both adults and children. A recent Asthma and Lung commissioned report suggested that giving all GPs in England access to FeNO could save the NHS £100million a year.
A raised FeNO level in someone with a diagnosis of asthma suggests they are not getting enough ICS to dampen down the inflammation causing their symptoms.
Firstly, this supports the clinician who may be applying a degree of guesswork as to the cause of someone’s asthma symptoms.
Secondly, a FeNO level provides an objective reading to support a discussion about inhaler technique and adherence – and can have significant educational benefits for the patient in linking behaviour to symptoms.
Thirdly, a raised FeNO level in someone with persistent asthma-like symptoms who is taking their ICS-containing preventer regularly and with the right technique gives the clinician confidence to increase the ICS dose.
As there are a lot of conditions that mimic asthma, such as anxiety, gastric reflux and vocal cord dysfunction, a low FeNO level would imply that there is no untreated inflammation in the airways and the clinician can be confident in not increasing the ICS dose.
NICE also recommends that if someone aged 12 and over has a raised FeNO, or eosinophil count, despite adherence to a moderate-dose MART regimen they should be referred to a severe asthma clinic for consideration of biologics.
3. Asthma is more common and severe in women than men
Research has shown that asthma is more prevalent and severe in women than in men, and has a greater impact on their quality of life.13 Women aged 20-50 are three times as likely as men to be admitted to hospital for asthma. In addition, asthma is five to seven times as common in obese women as in those of a normal weight.
As many as 25% of women with asthma have premenstrual asthma, where symptoms worsen during the premenstrual period. This appears to be related to hormonal influences on the underlying allergic inflammatory process – a growing evidence base is showing male and female sex hormones interact with different parts of the immune system, including lymphocytes and eosinophils.
Understanding the influence of hormones can help patients, and their clinicians, recognise the reason for fluctuations in their symptoms and manage them better. It also provides a possible opportunity for helping to prevent symptoms with hormone treatment, although more research is needed to understand this better.
4. Asthma still kills four people a day in the UK
In 2014 the National Review of Asthma Deaths (NRAD) showed that two-thirds of asthma deaths were preventable.14 Since then, in the UK asthma deaths have increased by a quarter.15 Such studies examining individual cases of deaths due to asthma have highlighted not only the opportunities the patient and the healthcare system had to prevent the death, but also how many other asthma attacks and asthma exacerbations could easily have become part of these mortality statistics. Identifying and addressing poor asthma control, and following up all exacerbations to optimise treatment, are two key actions which can improve the quality of care we provide and save lives.
5. Formoterol-ICS is safer and more effective than salbutamol as a reliever inhaler
Overuse of SABA and underuse of ICS have long been known to be risk factors for uncontrolled asthma, asthma exacerbations, hospitalisations and death.1,2 They were key preventable features identified in the NRAD.14
There are many reasons why people underuse preventer medication and over-rely on reliever inhalers, but one key reason is that people only notice benefit from their relief of symptoms. As formoterol works as quickly and as effectively as salbutamol, it can provide that symptom relief and is therefore a viable alternative to salbutamol. When combined with an inhaled steroid, formoterol-ICS provides symptomatic relief while helping address the underlying inflammation that causes symptoms and asthma exacerbations. Airway inflammation in asthma varies over time in response to triggers, which are also variable, so formoterol-ICS enables patients to automatically tailor their preventer medication in response to symptoms.16
As-needed ICS-formoterol (AIR therapy) reduced severe exacerbations by 55% compared with SABA monotherapy,17 while a MART regime reduced severe exacerbations by 32% compared to fixed-dose ICS-LABA with a SABA reliever.18
The joint NICE/BTS/SIGN guidelines have used the evidence for ICS-formoterol as a cornerstone to making asthma care safer and improving the UK’s asthma outcomes. They recommend AIR and MART as first-line treatments in adults and children over 12, and transferring anyone with poorly controlled asthma (due to symptoms, SABA use or any exacerbations) onto a MART regime.11
