Allergic rhinitis and asthma – the one airway disease

Asthma is characterised by variable respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough, and variable expiratory airflow limitation. It is usually associated with airway inflammation.¹ The exact cause of asthma remains unknown. Numerous triggers can cause symptoms, and these differ from person-to-person.

It is estimated that over 80 per cent of people with asthma have allergic rhinitis (AR). AR is also a risk factor for asthma, with 10-40 per cent of people who have AR also having asthma. AR is more likely to develop initially, with asthma developing later. Therefore, people with AR should be assessed for asthma. Similarly, patients with persistent asthma should be assessed for AR.

Typical symptoms of seasonal (hay fever) and perennial AR are:

• Sneezing;
• Itchy, blocked, or runny nose;
• Red, itchy, or watery eyes;
• Itchy throat, inner ear, or mouth;
• Postnasal drip;
• Headaches;
• Loss of concentration and generally feeling unwell;
• Reduced sensation of taste and smell.

The term ‘united airway disease’ or ‘one airway disease’ is opportune, as both rhinitis and asthma are chronic inflammatory diseases affecting both the upper and lower airways. Both conditions can be triggered by allergic or non-allergic triggers and present several phenotypes. Assessment and management of AR and asthma should be jointly carried out, leading to better control of both conditions.

In 2019, the classification of ‘seasonal’ and ‘perennial’ rhinitis was changed to ‘intermittent’ and ‘perennial’ rhinitis.² Intermittent rhinitis occurs less than four days per week or for less than four weeks. Persistent rhinitis lasts more than four days and longer than four weeks. Both intermittent and persistent AR can be mild or moderate/severe (see Figure 1).

Treatment

There are several treatment options available to the patient and a combination of these options may be required for optimal relief of symptoms. These are outlined in Table 1.

Saline douching/nasal irrigation should also be encouraged and is available either as a saline rinse or saline spray. Saline rinsing involves high volume at a low pressure, whereas saline spray is a low volume delivered at high pressure. The advantages of saline douching include:

• Direct cleansing;
• Removal of mucous and inflammatory mediators;
• Reduces bacterial burden;
• Reduces mucus thickness;
• Improves mucociliary function by increasing ciliary beat frequency.
• If the nasal spray is being used for the first time, priming is required:
• Blow the nose prior to use;
• Tilt the head forward;
• Use right hand to left nostril, left hand to right nostril;
• Aim the nozzle of the spray away from the nasal septum and towards the outer aspect of the nose;
• Avoid sniffing deeply. If the nasal spray can be tasted, the patient is probably sniffing too deeply.

Smoking cessation should be encouraged at every opportunity. Smoking increases the likelihood of chronic nasal symptoms and may be associated with the development of nasal polyposis. Passive smoking, environmental exposure, e-cigarettes, and vaping also increase the likelihood of chronic nasal symptoms and nasal polyposis.

Mild intermittent AR treatment options include oral and nasal decongestants, which can be used as a rescue medication. These medications will reduce nasal congestion and should be used for no longer than seven days and should be avoided in pregnancy and breastfeeding. Oral H1 antagonists block the physiological effects from mast cell-derived histamine. Second-generation antihistamines are preferred due to their less sedating effect and are available over the counter. Antihistamines are also available intranasally or intraocular.

Intranasal corticosteroid (INCS) is the first-line treatment for moderate/severe intermittent and persistent AR. These medications are used once-or-twice daily in each nostril and good technique is essential and should be checked at every opportunity. If the nasal cavity is very obstructed, a nasal spray may not be effective. Nasal drops may be more effective in this scenario. The efficacy of INCS is not improved when used with oral corticosteroids (OCS).

Sublingual immunotherapy (SLIT)/allergen immunotherapy (AIT) is now recommended by GINA (2021) as a treatment option for patients with asthma who are sensitised and have AR. Immunotherapy is also recommended by ARIA (2019) for patients with AR who do not achieve an optimal response from oral H1 or INCS therapies. These medications, which are not available on the General Medical Services (GMS), can be prescribed by GPs. There are three SLIT/AIT products available in Ireland to treat allergy – grass pollen, tree pollen, and house dust mite allergy.

Figure 2 provides a stepwise approach to the management of AR.

Endonasal phototherapy has an immunosuppressive effect by inhibiting allergen-induced histamine release from mast cells. It also induces apoptosis in the T lymphocytes and eosinophils. The procedure directs a combination of UV-B, UV-A, and visible light into the nasal cavity. Endonasal phototherapy is generally well-tolerated and effective, and is a treatment option when pharmacological treatment is insufficient or contraindicated.

It is considered that AR is a medical condition that requires medical intervention. However, if symptoms are unilateral or if there is a septal deviation, nasal polyps, or tumour present, surgery should be considered. Patients will still need to have an AR plan in place post-surgical intervention.

There are a number of lifestyle interventions that can improve symptoms:

• Keep windows closed at night-time or when the pollen count is high.
• Monitor pollen levels on www.met.ie/forecasts/pollen and minimise time spent outdoors when the pollen
  count is high.
• Apply Vaseline around the nostrils when outdoors to trap pollen.
• Wear wraparound sunglasses to minimise levels of pollen irritating the eyes. Splash the eyes with cold water to help flush out pollen and soothe and cool the eyes.
• Shower, wash your hair, and change clothes if you have been outdoors for an extended time.
• Exercise in the morning rather than the evening when there are higher rates of pollen falling.
• Avoid drying clothes outdoors and shake clothes outside before bringing them inside, particularly bedclothes.
• Minimise contact with pets that have been outdoors and are likely to carry pollen.
• Put an asthma action plan in place.

An asthma action plan contains all the information a person with asthma needs to keep their condition under control. Every person with asthma should be offered a plan. It should be reviewed frequently, and any time medication is changed. These can be downloaded from www.asthma.ie and should be filled out with the patient’s healthcare professional.

Special considerations

Children under four years
Figure 3 illustrates the typical age of onset of allergies in children. Outdoor allergens are unusual in children under two. Type 2 sub-endotype IL4/IL-13 is associated with AR in children. IL-5 is associated with asthma.

Treatment of children aged under four years should focus on allergen avoidance and saline spray. Cetirizine is the oral H1 antagonist of choice. Cetirizine is licensed from two years, but good safety is reported from six months of age. For moderate/severe persistent AR, intranasal corticosteroids such as fluticasone or mometasone should be considered first-line treatment. Long-term follow-up studies suggest no growth retardation if used as a once-daily dose. Caution should be taken in children who are also using inhaled or topical corticosteroids for asthma or dermatitis. In children with resistant symptoms and those with co-existing asthma, leukotriene receptor antagonists (LTRA) should be considered. Parents should be educated about possible side-effects of sleep disturbance and mood disorders.

Pregnancy

AR affects 20 per cent of pregnancies, and women with pre-existing AR can experience an increase in symptoms. Medications should be avoided where possible and should only be used if benefits to the mother are greater than the risk to the foetus. Medication should be avoided in the first trimester if possible. Topical administration of medication should be the first line where possible.

Conclusion

This article has explored the relationship between asthma and AR. Pharmacological and non-pharmacological interventions for the management of AR have been discussed. Special considerations in children and pregnancy have also been addressed.

The impact of AR on health and wellbeing is significant, with many people experiencing impairment
of daily activities, learning and cognitive function, as well as reduced productivity at work and school. Optimal control of symptoms through pharmacological and non-pharmacological treatment regimens in combination with education, self-management, and empowerment is paramount to managing this condition.

References