Allergic rhinitis: classification, diagnosis and treatment

Rhinitis is characterised by a combination of nasal symptoms including itching, sneezing, rhinorrhoea, and nasal congestion caused by inflammation of the nasal mucosa. When these symptoms are triggered due to allergen exposure, it is known as allergic rhinitis. Rhinitis symptoms can also be present in patients without any evidence of allergic triggers. This is known as non-allergic rhinitis and includes types such as infectious, occupational or drug-induced rhinitis (Bousquet et al, 2008; Scadding et al, 2017).

Allergic rhinitis is the most common form of rhinitis and is an immunoglobulin E (IgE)-mediated inflammatory disorder that occurs because of allergen exposure. Sneezing and rhinorrhoea are early symptoms of allergic rhinitis. These are caused by the release of histamine, prostaglandin and leukotriene by the activated mast cells in response to exposure to allergen. This is known as an early phase reaction. Nasal obstruction results from the remodelling of the nasal mucosa as a result of the late inflammatory phase (Bousquet et al, 2008; Scadding et al, 2017). Other symptoms derived from allergic rhinitis are tiredness and poor concentration. These symptoms have a large impact on patients’ quality of life by affecting their sleep, social life and work/school performance. Despite the reduction in patients’ quality of life, allergic rhinitis remains under-recognised (Bousquet et al, 2008; Scadding et al, 2017).

Rhinitis affects 26% of adults and 10-15% of children in the UK. It reaches its peak prevalence in adults aged between 30-40 years old and shows remission throughout adult life. In the UK and Western Europe, there has been a remarkable increase in the prevalence over the last four to five decades. Globally, there seems to be an association between the economic and industrial development of a country and the occurrence of allergic rhinitis (Scadding et al, 2017).

Classification of allergic rhinitis

Allergic rhinitis can be classified depending on the frequency and severity of symptoms as per the World Health Organisation Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines. Intermittent symptoms refer to symptoms that appear less than 4 days a week or for less than 4 consecutive weeks, whereas persistent symptoms are present for more than 4 days a week or over 4 consecutive weeks. If symptoms are not described as bothersome and do not affect sleep, work or school, they are classified as mild; however, those that are distressing and disrupt daily activities are defined as moderate-severe symptoms (Table 1). This classification can be helpful to establish the most appropriate level of treatment for each patient (Bousquet et al, 2008; Kariyawasam and Rotiroti, 2022).

Allergic rhinitis can be further sub-divided into seasonal and perennial (Bousquet et al, 2008). Seasonal rhinitis is often caused by outdoor allergens such as pollen or moulds, whereas perennial rhinitis is related to indoor allergens including house dust mite (HDM), animal dander, moulds or insects (Bousquet et al, 2008; Scadding et al, 2017). Although this classification is not entirely suitable for the description of allergic rhinitis globally, it can be useful in countries such as the UK where different seasons are present. This division can help with identifying the most active disease and guide the initiation of the therapy around the seasons (Kariyawasam and Rotiroti, 2022).

Diagnosis

Allergic rhinitis is diagnosed when there is a concordance between the clinical history and the diagnostic tests (Bousquet et al, 2008).

Obtaining a good history of the allergic symptoms is essential to understand their severity. Symptoms may include sneezing, rhinorrhoea and nasal obstruction. Some patients may also suffer from eye symptoms. A detailed history should include identification of the potential triggers, allergen location (indoors/outdoors) and seasonality (Bousquet et al, 2008; Scadding et al, 2017).

The main diagnostic tests used for the diagnosis of allergic rhinitis are skin prick tests (SPT) and serum-specific IgE. Skin prick testing is a safe procedure and is used to confirm an IgE-mediated allergic reaction in the skin to the specific allergen used. Skin wheals confirm allergen sensitisation within 15 minutes of testing, which provides the patient with a visual result. When the SPT cannot be undertaken or there is a discordance between the SPT results and the clinical history, serum-specific IgE are indicated. Many asymptomatic people can have a positive skin prick test or serum-specific IgE result, therefore only the concordance between the history and the results from these tests will determine the diagnosis (Bousquet et al, 2008; Kariyawasam and Rotiroti, 2022).

Other investigations such as nasal challenges, nasal endoscopies or nasal airflow measurement are not routinely used in practice, but their use may be applicable to individual patients to confirm or exclude the differential diagnosis (Bousquet et al, 2008).

Treatment

Treatment for allergic rhinitis includes allergen avoidance, pharmacological therapies and patient education. These aim to control the patient's symptoms to improve their quality of life (Scadding et al, 2017).

The initial management of allergic rhinitis involves allergen exposure prevention advice. This measure is known to be effective; however, this is not enough as a single measure and needs to be combined with pharmaceutical therapy. The practical measures that can be advised to patients for allergen avoidance are summarised in the Table 2.

The pharmacological therapy pathway to treat mild and moderate-severe allergic rhinitis is summarised in Figure 1. Oral H1-antihistamines are the first line therapy in treating mild to moderate symptoms (Scadding et al, 2017). Second generation antihistamines (eg fexofenadine, cetirizine) are the preferred option in view of their non-sedative and non-anticholinergic properties (Shamsi and Hindmarch, 2000; Liu et al, 2005). Intranasal sprays containing either antihistamines or steroids are also recommended for allergic rhinitis. While intranasal antihistamine (azelastine) can be used in mild allergic rhinitis, intranasal steroids (eg fluticasone furoate, mometasone furoate) are the firstline treatment for moderate-severe allergic rhinitis and nasal obstruction (Lee and Pickard, 2007; Horak, 2008). Intranasal combination therapy with both steroids and antihistamines is recommended as second line when intranasal monotherapy fails (Scadding et al, 2017).

Ocular therapy is also used when eye symptoms are present in allergic rhinitis. Ocular mast cell stabilisers (eg sodium cromoglicate) and antihistamines (eg olopatadine) are used for eye symptoms if they are not suppressed by oral antihistamines or intranasal therapy. Artificial tears may also help with the relief of ocular symptoms (Scadding et al, 2017).

Allergen immunotherapy is recommended for patients with a confirmation of IgE sensitivity and uncontrolled symptoms despite maximal pharmacotherapy. Immunotherapy can not only improve symptoms and quality of life but can also reduce the medication required (Bousquet et al, 2008; Scadding et al, 2017). It also has a role in the modification of the natural course of allergic rhinitis, leading to its possible long-term remission (Walker et al, 2011).

Immunotherapy can be administered subcutaneously (SCIT) or sublingually (SLIT) over a 3-year course in the UK. While SLIT can be self-administered at home due to a safer profile, SCIT can only be administered in specialist clinics due to the risk of systemic side-effects such as anaphylaxis or allergic reactions (Scadding et al, 2017).

Education is a key step in the treatment of allergic rhinitis, which can lead to improving adherence to medication and result in better patient outcomes (Royal Pharmaceutical Society, 2013). Not only is describing the role and safety profile of medication necessary, but also counselling the patient on the correct nasal spray technique (Scadding et al, 2017).

CPD reflective practice:

• How could you assess the impact of allergic rhinitis on your patient's life?
• What practical measures could you suggest to help patients avoid allergen exposure?
• Are you confident discussing treatment failure with patients and exploring the potential reasons for this?

Key points

• Allergic rhinitis is the most common form of rhinitis and is an immunoglobulin E (IgE)-mediated inflammatory disorder that occurs because of allergen exposure
• Symptoms of allergic rhinitis have a large impact on patients’ quality of life by affecting their sleep, social life and work/school performance
• Allergic rhinitis is diagnosed when there is a concordance between the clinical history and the diagnostic tests
• Treatment for allergic rhinitis includes allergen avoidance, pharmacological therapies and patient education

Conclusion

Allergic rhinitis is an IgE-mediated inflammatory disease of the nasal mucosa characterised by symptoms such as sneezing, nasal obstruction and runny nose. These symptoms have a negative impact on patients’ quality of life (Scadding et al, 2017).

Allergic rhinitis can be classified as intermittent or persistent depending on the symptom frequency and severity (either mild or moderate-severe). However, further sub-division in seasonal or perennial allergic rhinitis could be useful in countries with distinct seasons like the UK (Bousquet et al, 2008; Kariyawasam and Rotiroti, 2022).

The diagnosis of allergic rhinitis is based on a detailed clinical history and positive skin prick test and/or serum-specific IgE results. Positive results are not clinically relevant if allergic rhinitis symptoms are not present (Bousquet et al, 2008; Kariyawasam and Rotiroti, 2022).

The management of allergic rhinitis involves a combination of allergen exposure avoidance measures, pharmacological therapy, and patient education (Bousquet et al, 2008; Scadding et al, 2017).