Asthma is an inflammatory condition that affects approximately 12% of the population, or 8 million people, some of whom may be asymptomatic and off treatment. However, at any given time, around 5.4 million people are receiving treatment for asthma (National Institute for Health and Care Excellence [NICE], 2021). The diagnosis is made when a patient presents with typical symptoms of a cough, wheezing, tight chest and/or shortness of breath, along with other key elements such as a family history of asthma or a personal or family history of atopy, the presence of triggers and evidence of variable airflow obstruction which reverses with treatment (British Thoracic Society/Scottish Intercollegiate Guidelines Network [BTS/SIGN], 2019). The variability in symptoms can be evident in different ways – through the episodic nature of the symptoms, diurnal variation (symptoms are often worse during the night or in the early morning) or through seasonal changes (Global Initiative for Asthma [GINA], 2021).
This article aims to evaluate how seasonal changes can affect asthma pathophysiology, influence symptoms and impact on its management. The key learning outcomes include:
- Revisiting the pathophysiology and diagnosis of asthma
- Considering the aims of asthma management
- Reflecting on how different seasons, seasonal allergens and weather patterns impact on asthma morbidity and mortality
- Evaluating the management of seasonal asthma.
The pathophysiology and diagnosis of asthma
Asthma is an inflammatory condition where the airways have become hyperreactive in response to a trigger (eg house dust mite, pollen, cats, viruses and temperature changes). The inflammatory cascade associated with asthma symptoms includes immunoglobulin E (IgE) antibodies, which bind to mast cells and basophils. The mast cells release cytokines, which are immunomodulating proteins and include histamine, prostaglandins, leukotrienes and interleukins, all of which lead to the inflammation and bronchoconstriction seen in asthma (Sinyor and Concepcion Perez, 2021).
A careful history can identify the likelihood of an asthma diagnosis, and spirometry will highlight the presence of an obstructive pattern, which reverses with bronchodilators, and which is consistent with the suspected diagnosis (BTS/SIGN, 2019). Reversibility testing will also confer symptom relief, but the key to resolving symptoms in the long term is based on treating the underlying inflammation. This is primarily achieved through the use of inhaled corticosteroids (ICS) (BTS/SIGN, 2019).
The aim of asthma management
Asthma management aims to ensure complete control of the symptoms, with the minimum amount of medication, allowing the individual to work, play sports and participate in all of the activities that people without asthma can enjoy. The term ‘complete control’ means that asthma causes no daytime symptoms, no night-time waking, no acute asthma attacks, no need for rescue medication, no limitations on day-to-day activity or exercise, normal (or near-normal) lung function and no side effects from treatment (BTS/SIGN, 2019). There are several guidelines available on the management of asthma including BTS/SIGN (2019), GINA (2021) and NICE (2017), which explain, in generic terms, the scientific approach to how people with asthma can be treated. The art of asthma care revolves around turning these generic guidelines into something that fits each individual. This is particularly important when the guidelines all take different approaches to the pharmacological management of asthma.
For most people with asthma, daily ICS therapy will be required to control the inflammation, and according to national guidelines, the use of reliever medication should not exceed three times a week (BTS/SIGN, 2019). However, there is a move to encourage clinicians and people living with asthma (PLwA) to use combination inhalers (ie an ICS with a long-acting beta2 agonist (LABA) incorporated in one inhaler device) to treat the underlying inflammation and relieve symptoms concurrently (GINA, 2021). There is also an increasing focus on the maintenance and reliever therapy (MART) approach, where the same inhaler is used ‘as required’ for symptom control, as well as being used twice daily (GINA, 2021). The MART approach has been studied for over 20 years and is effective in improving control and reducing exacerbations at a lower overall dose of medication when compared with fixed dosing regimens (FitzGerald et al, 2003; Ind et al, 2004). MART regimes using dry powder inhalers (DPIs) are also environmentally preferable, as blue ‘reliever’ metered-dose inhalers (MDIs) are known to contribute significantly to environmental damage from greenhouse gases (Janson et al, 2020).
Seasonal asthma
Meteorological conditions and air pollution have been shown to impact acute exacerbations of asthma leading to hospital admissions (Bodaghkhani et al, 2019; D'Amato et al, 2015; Yu et al, 2020). Changing seasons can lead to an increase in asthma symptoms for a range of reasons. In spring and summer, airborne allergens such as pollens and spores can be a particular problem, along with a tendency towards poorer air quality, which can affect people with respiratory problems such as asthma (London Air, 2022). As mentioned above, the aim of asthma management is to reverse the inflammation that causes the symptoms so PLwA are symptom free and able to live a normal life with no asthma-related restrictions. However, PLwA may underestimate their ability to achieve this and accept symptoms as being part of their life (Chapman et al, 2008). They may expect to have an increase in symptoms during the hay fever season or may recognise how the weather impacts on their asthma, without realising that it is possible to manage these seasonal variations. Seasonal allergic rhinitis (SAR) is a common comorbidity of asthma, leading to specific SAR symptoms and negatively impacting on asthma control (Takemura et al, 2016). PLwA have a high probability of having concomitant SAR and yet may not recognise how much this can affect their asthma control: SAR is a key cause of asthma symptoms, exacerbations and even asthma deaths, especially in children and young people (Royal College of Physicians, 2015; D'Amato et al, 2016). The Allergic Rhinitis and Its Impact on Asthma (ARIA) guidelines were updated in 2020 to take more consideration of real-world evidence but continue to stress the importance of identifying and treating SAR to manage symptoms and improve asthma control (Bousquet et al, 2020).
Another potential risk factor for asthma attacks is thunderstorms. Thunderstorm-triggered asthma is a recognised phenomenon where a rise in asthma symptoms and acute asthma attacks is seen immediately following a thunderstorm. This phenomenon is thought to be the result of a combination of weather conditions leading to increases in the concentration and dispersal of aeroallergens, particularly tree pollens (Harun et al, 2019). PLwA who are most at risk from thunderstorm-triggered exacerbations include those who have allergic rhinitis or pollen allergies and those who have had a hospital admission for asthma in the previous year. However, in line with other types of exacerbation, PLwA who have better adherence to their preventer medication (ICS with or without LABA) have less risk of thunderstorm-triggered exacerbations than those with good adherence, highlighting the importance of taking preventer treatment as prescribed to reduce the risk of uncontrolled symptoms throughout the year (Harun et al, 2019).
Autumnal spikes in asthma attacks are known to occur, particularly in children with asthma (Satia et al, 2020). This is thought to be due to a combination of them returning to school, with an increased risk of exposure to viral infections, along with a rise in other aeroallergens. The impact of these triggers may be exacerbated because changes to a daily routine during the summer may have led to a decreased adherence to regular therapy. It is interesting to note that asthma admissions and respiratory tract infections increase in September but do not occur after returning to school after other school holiday periods outside of September (Satia et al, 2020).
In winter, cold weather and the presence of flu, cold and COVID viruses are known to impact on asthma symptoms and during the pandemic, when greater attention was paid to measures such as hand washing and wearing masks, and where there may have been an increase in medication adherence, there was a reduction in asthma exacerbations (Salciccioli et al, 2021). PLwA need to appreciate the likely benefits from maintaining these practices as well as getting their relevant vaccinations and optimising their asthma management to be winter ready (Abrams et al, 2020).
Resources
- Allergy UK: https://www.allergyuk.org/health-professionals
- Association of Respiratory Nurse Specialists (ARNS): https://arns.co.uk/
- Asthma and Lung UK: https://www.asthmaandlung.org.uk/
- British Lung Foundation: https://www.blf.org.uk/
- Primary Care Respiratory Society (PCRS): https://www.pcrs-uk.org/
Treating seasonal asthma
The management of seasonal asthma should include pharmacological, lifestyle and non-pharmacological approaches. Avoidance of allergens is recommended, where possible. Pollen counts tend to be highest in the early morning and early evening, so minimising time outdoors during this time of the day may help to reduce the impact of allergens on nasal symptoms and asthma. Non-pharmacological interventions may include nasal douching, which has been shown to be effective for allergic rhinitis and post-nasal drip in some people (Head et al, 2018).
The international EUFOREA Allergic Rhinitis treatment algorithm recommends that the diagnosis of allergic rhinitis should be confirmed through the presence of two or more symptoms, including runny nose, sneezing, nasal obstruction, nasal itch and eye symptoms (itch, redness or tearing) for at least one hour on most days when related to allergen exposure (EUFOREA, 2021). Once the diagnosis has been made, a stepped approach to treatment should be taken, which may include an intranasal steroid, an oral or intranasal antihistamine, or a combination of these treatments, with combination nasal sprays being recommended for people with uncontrolled symptoms (Hellings et al, 2020; EUFOREA, 2021). An example of an intranasal steroid/antihistamine nasal spray would be Dymista™, which is recommended for people age 12 and above at a dose of one actuation into each nostril twice daily.
People with asthma who also suffer from seasonal allergic rhinitis (SAR) can be prescribed a leukotriene receptor antagonist (LTRA) such as montelukast, which when used with an inhaled corticosteroid, can effectively treat both the asthma and the SAR (Zuberi et al, 2020). Montelukast is licensed for use from age 6 months and above but prescribers should be mindful of the Medicines and Healthcare Products Regulatory Agency (MHRA) warning about this medication's neuropsychiatric effects (MHRA, 2019). The GINA guidelines recommend that in people with seasonal asthma and no interval symptoms outside of this season, they should start their ICS at the onset of symptoms and continue for four weeks after their relevant pollen season ends (GINA, 2021). Alternatively, GINA suggests that an ‘as required’ ICS/formoterol combination can be prescribed to offer symptom relief while concurrently treating the underlying inflammation. This recognises the importance of human behaviour and preferences when selecting appropriate seasonal asthma treatment and minimises the risk of people using SABA therapy alone (O'Byrne et al, 2018). Incidentally, GINA also recommends PRN ICS/formoterol in mild, non-seasonal asthma. At the time of writing, PRN ICS/formoterol was not licensed for use. The MHRA advises that medication may be used off label if the prescriber recognises the extent of their clinical competence and the relevant professional codes and ethics of their governing bodies before prescribing (MHRA, 2014).
Some people may report that their symptoms are only a problem to them in a particular season and that they do not get symptoms outside of that season. As a result, they may prefer to use their preventer inhaler for that period alone and come off treatment when they are symptom-free. While this is entirely understandable, the pathophysiological changes that occur in asthma may contribute towards airway remodelling when untreated and there is some evidence to suggest that the underlying inflammation which causes atopic asthma is present even when symptoms are not (Murdoch and Lloyd, 2010). If PLwA are made aware of this phenomenon, they could make an informed decision to take their ICS therapy all year round. If they opt to use their inhaler for part of the year only, their personalised asthma action plan (PAAP) should indicate when they should start their preventer inhaler to minimise the risk of asthma symptoms and attacks, based on when their seasonal asthma symptoms tend to begin. This is why a personalised asthma action plan is so important. Asthma action plans should always include a reminder about triggers and advice on trigger avoidance where possible.
Conclusion
Asthma is an inflammatory disease in which the allergic cascade plays a key part in the pathophysiology and symptoms. The diagnosis of asthma is made through careful history taking to identify key symptoms and risk factors along with objective tests, which can reveal the presence of reversible airflow obstruction. Allergic rhinitis is a common comorbidity of asthma and the presence of two or more typical symptoms should indicate when treatment may be initiated. Asthma management aims to achieve total control, where the person living with asthma can live a full life, unrestricted by asthma symptoms, on minimal treatment. The weather, the seasons, meteorological conditions and pollution can all have a negative effect on asthma morbidity and mortality. Avoiding triggers and allergens and maintaining effective control at all times can reduce this risk. Treating allergic rhinitis effectively can improve the rhinitis symptoms and offer improved asthma control. Clinicians should take an individualised, patient-centred approach to asthma management, ensuring that people with asthma have enough information to enable them to make informed decisions about their treatment and self-management. This will include using a shared decision-making approach to treating that person's asthma in line with the underlying pathophysiology, known triggers, symptom presentation, previous history of asthma exacerbations and individual preferences. Ensuring that people living with asthma have the knowledge and expertise to self-manage effectively in order to achieve and maintain complete control is likely to minimise risk and optimise outcomes.