Is subcutaneous immunotherapy (SCIT) as effective as sublingual immunotherapy (SLIT) for allergic rhinitis?

From the Guidelines

Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are both effective treatments for allergic rhinitis, with comparable overall efficacy, but the choice between them should be based on individual patient factors, including safety, convenience, and personal preference, as highlighted in the most recent guideline 1. When considering the treatment options for allergic rhinitis, it is essential to weigh the benefits and risks of each approach. SCIT involves regular injections administered in a medical setting, typically starting with weekly injections for 3-6 months followed by monthly maintenance injections for 3-5 years. On the other hand, SLIT involves daily self-administration of allergen extracts under the tongue at home, typically for 3-5 years.

Key Considerations

• Efficacy: Both SCIT and SLIT have been shown to be effective in reducing symptoms of allergic rhinitis, with some studies suggesting that SCIT may have a slight advantage in efficacy for some patients, particularly those with multiple allergies or more severe symptoms 1.
• Safety: SLIT offers better safety, with a lower risk of systemic reactions compared to SCIT, which carries a small risk of severe allergic reactions, requiring administration in medical facilities with observation periods 1.
• Convenience: SLIT is generally more convenient, as it can be administered at home, whereas SCIT requires regular visits to a medical facility for injections.
• Tolerability: SLIT is often better tolerated by patients, especially children, with the most common side effects being limited to local oral irritation, whereas SCIT can cause local reactions at the injection site.

Treatment Choice

The choice between SCIT and SLIT should be based on individual patient factors, including:

• Specific allergen sensitivities
• Symptom severity
• Compliance ability
• Access to healthcare facilities
• Preference regarding administration method Both treatments work by gradually desensitizing the immune system to specific allergens, shifting the immune response from an allergic Th2 pattern to a more tolerant Th1 pattern, ultimately reducing symptoms when exposed to the allergen 1.

From the Research

Comparison of Subcutaneous and Sublingual Immunotherapy

• Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are both effective treatments for allergic rhinitis, with evidence showing they can modify the underlying cause of the disease and provide long-term benefits 2.
• Studies have confirmed that both SCIT and SLIT are effective in patients with seasonal allergic rhinitis, while evidence for their efficacy in patients with perennial disease is less convincing 2, 3.
• A systematic review and meta-analysis found that SLIT significantly reduced symptoms and medication requirements in patients with allergic rhinitis, with a significant reduction in both symptoms and medication scores 3.
• Recent studies have demonstrated that SCIT and SLIT have similar efficacy in reducing symptoms and medication requirements, with some studies suggesting that SLIT may have more local side effects but fewer systemic ones 4, 5.
• The choice between SCIT and SLIT may depend on various factors, including local availability of products, patient preference, and the presence of multiple allergen sensitizations 2, 5.

Efficacy and Safety Considerations

• Both SCIT and SLIT have been shown to be effective in reducing symptoms and medication requirements in patients with allergic rhinitis, with some studies suggesting that SCIT may be more effective in certain cases 4.
• SLIT has been associated with a higher incidence of local symptoms, but these are generally mild and do not usually persist beyond the first few weeks 4.
• Systemic reactions are less frequent with SLIT compared to SCIT, and no fatal or near-fatal reactions have been reported with SLIT 4.
• The relative clinical efficacy of SCIT and SLIT remains to be defined, with head-to-head studies with well-defined effective doses by the two routes urgently needed 4.

Therapeutic and Real-World Considerations

• Shared decision-making should be instituted to determine which treatment should be started in a patient with allergic rhinitis, taking into account factors such as patient preference, local availability of products, and the presence of multiple allergen sensitizations 5.
• Clinical trials have demonstrated the efficacy and safety of both SCIT and SLIT in the treatment of allergic rhinitis, with ongoing studies aiming to further define their relative efficacy and safety profiles 5.
• The use of SCIT and SLIT in the real world is influenced by various factors, including patient demographics, disease severity, and access to healthcare services 5.