A double-blind study of the discontinuation of ragweed immunotherapy

Clinical Practice Guideline: Immunotherapy for Inhalant Allergy

OBJECTIVE

Allergen immunotherapy (AIT) is the therapeutic exposure to an allergen or allergens selected by clinical assessment and allergy testing to decrease allergic symptoms and induce immunologic tolerance. Inhalant AIT is administered to millions of patients for allergic rhinitis (AR) and allergic asthma (AA) and is most commonly delivered as subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT). Despite its widespread use, there is variability in the initiation and delivery of safe and effective immunotherapy, and there are opportunities for evidence-based recommendations for improved patient care.

PURPOSE

The purpose of this clinical practice guideline (CPG) is to identify quality improvement opportunities and provide clinicians trustworthy, evidence-based recommendations regarding the management of inhaled allergies with immunotherapy. Specific goals of the guideline are to optimize patient care, promote safe and effective therapy, reduce unjustified variations in care, and reduce the risk of harm. The target patients for the guideline are any individuals aged 5 years and older with AR, with or without AA, who are either candidates for immunotherapy or treated with immunotherapy for their inhalant allergies. The target audience is all clinicians involved in the administration of immunotherapy. This guideline is intended to focus on evidence-based quality improvement opportunities judged most important by the guideline development group (GDG). It is not intended to be a comprehensive, general guide regarding the management of inhaled allergies with immunotherapy. The statements in this guideline are not intended to limit or restrict care provided by clinicians based on their experience and assessment of individual patients.

ACTION STATEMENTS

The GDG made a strong recommendation that (Key Action Statement [KAS] 10) the clinician performing allergy skin testing or administering AIT must be able to diagnose and manage anaphylaxis. The GDG made recommendations for the following KASs: (KAS 1) Clinicians should offer or refer to a clinician who can offer immunotherapy for patients with AR with or without AA if their patients' symptoms are inadequately controlled with medical therapy, allergen avoidance, or both, or have a preference for immunomodulation. (KAS 2A) Clinicians should not initiate AIT for patients who are pregnant, have uncontrolled asthma, or are unable to tolerate injectable epinephrine. (KAS 3) Clinicians should evaluate the patient or refer the patient to a clinician who can evaluate for signs and symptoms of asthma before initiating AIT and for signs and symptoms of uncontrolled asthma before administering subsequent AIT. (KAS 4) Clinicians should educate patients who are immunotherapy candidates regarding the differences between SCIT and SLIT (aqueous and tablet) including risks, benefits, convenience, and costs. (KAS 5) Clinicians should educate patients about the potential benefits of AIT in (1) preventing new allergen sensitizations, (2) reducing the risk of developing AA, and (3) altering the natural history of the disease with continued benefit after discontinuation of therapy. (KAS 6) Clinicians who administer SLIT to patients with seasonal AR should offer pre- and co-seasonal immunotherapy. (KAS 7) Clinicians prescribing AIT should limit treatment to only those clinically relevant allergens that correlate with the patient's history and are confirmed by testing. (KAS 9) Clinicians administering AIT should continue escalation or maintenance dosing when patients have local reactions (LRs) to AIT. (KAS 11) Clinicians should avoid repeat allergy testing as an assessment of the efficacy of ongoing AIT unless there is a change in environmental exposures or a loss of control of symptoms. (KAS 12) For patients who are experiencing symptomatic control from AIT, clinicians should treat for a minimum duration of 3 years, with ongoing treatment duration based on patient response to treatment. The GDG offered the following KASs as options: (KAS 2B) Clinicians may choose not to initiate AIT for patients who use concomitant beta-blockers, have a history of anaphylaxis, have systemic immunosuppression, or have eosinophilic esophagitis (SLIT only). (KAS 8) Clinicians may treat polysensitized patients with a limited number of allergens.

Immunology of allergen immunotherapy

Allergen immunotherapy (AIT) is the only disease-modifying therapy for allergic disease. Through repeated inoculations of low doses of allergen-either as whole proteins or peptides-patients can achieve a homeostatic balance between inflammatory effectors induced and/or associated with allergen contact, and mediators of immunologic non-responsiveness, potentially leading to sustained clinical improvements. AIT for airborne/respiratory tract allergens and insect venoms have traditionally been supplied subcutaneously, but other routes and modalities of administration can also be effective. Despite differences of allergen administration, there are some similarities of immunologic responses across platforms, with a general theme involving the restructuring and polarization of adaptive and innate immune effector cells. Here we review the immunology of AIT across various delivery platforms, including subcutaneous, sublingual, epicutaneous, intradermal, and intralymphatic approaches, emphasizing shared mechanisms associated with achieving immunologic non-responsiveness to allergen.

Long-term efficacy of the sublingual and subcutaneous routes in allergen immunotherapy

Allergen immunotherapy is highly effective in selected patients with allergic rhinitis, allergic asthma, and Hymenoptera venom allergy. Unlike anti-allergic drugs, both subcutaneous and sublingual immunotherapies have been shown to modify the underlying cause of the disease, with proved long-term clinical benefits after treatment cessation. In this review, we analyzed 10 randomized, double-blind, placebo controlled clinical trials of allergen immunotherapy that included blinded follow-up for at least 1 year after treatment withdrawal. Three studies of pollen subcutaneous immunotherapy provided evidence that a sustained, tolerogenic effect of subcutaneous immunotherapy can be achieved after 3 years of treatment. Six trials of sublingual immunotherapy provided robust evidence for long-term clinical benefit and persistent immunologic changes after grass pollen, house-dust mite, or Japanese cedar immunotherapy, whereas a clinical trial of both sublingual and subcutaneous grass pollen immunotherapies showed that 2 years of immunotherapy were efficacious but insufficient to induce long-term tolerance. These studies strongly supported international guidelines that recommend at least 3 years of allergen immunotherapy of proven value to achieve disease modification and sustained clinical and immunologic tolerance.

Dynamic Changes, Correlation of Basophils, and the Therapeutic Effect in Patients With Allergic Rhinitis During Allergen-specific Immunotherapy

BACKGROUND

The role of basophils in allergic rhinitis (AR) has been studied extensively; however, there are very few reports on changes in basophils after allergen-specific immunotherapy (SIT).

OBJECTIVE

To examine the changes and correlation of peripheral blood basophils and the therapeutic effect in patients with AR during allergen-SIT.

METHODS

A total of 77 patients with AR who were allergic only to house dust mites received allergen-SIT. At 3 time points, patients underwent testing for the percentage and activation rate of basophils in peripheral blood, skin index (SI) measurement, visual analog scale (VAS) assessment, and rhinoconjunctivitis quality of life questionnaire (RQLQ) evaluation. The results were compared to a control group with congenital preauricular fistula.

RESULTS

(1) Before treatment, the percentage and activation rate of basophils in patients with AR were significantly higher than those in controls. There was no significant difference in the percentages and activation rates of basophils at the 3 time points. (2) The SIs, VAS, and RQLQ scores of the patients immediately after treatment and 2 years posttreatment decreased significantly compared to those before treatment; the SI, VAS, and RQLQ scores of the patients 2 years posttreatment increased significantly compared with those immediately after treatment. (3) There was no correlation between the patients' basophil activation rate and percentage and the SI, VAS, and RQLQ scores at all time points.

CONCLUSION

The percentage and activation rate of basophils were higher in patients with AR than in controls. The values did not change significantly after allergen-SIT and showed no correlation with treatment effectiveness. Therefore, the frequency and activation rate of basophils cannot be used as criteria for assessing the effectiveness of allergen-SIT for house dust mites. Allergen-SIT is effective for the management of AR, but the effect declines after the completion of therapy.

Immunological Responses and Biomarkers for Allergen-Specific Immunotherapy Against Inhaled Allergens

Long-term efficacy that occurs with allergen immunotherapy of proven value is associated with decreases in IgE-dependent activation of mast cells and tissue eosinophilia. This suppression of type 2 immunity is accompanied by early induction of regulatory T cells, immune deviation in favor of T_H1 responses, and induction of local and systemic IgG, IgG₄, and IgA antibodies. These "protective" antibodies can inhibit allergen-IgE complex formation and consequent mast cell triggering and IgE-facilitated T_H2-cell activation. Recent studies have highlighted the importance of innate responses mediated by type 2 dendritic cells and innate lymphoid cells in allergic inflammation. These cell types are under the regulation of cytokines such as thymic stromal lymphopoietin and IL-33 derived from the respiratory epithelium. Novel subsets of regulatory cells induced by immunotherapy include IL-35-producing regulatory T cells, regulatory B cells, a subset of T follicular regulatory cells, and IL-10-producing group 2 innate lymphoid cells. These mechanisms point to biomarkers that require testing for their ability to predict clinical response to immunotherapy and to inform novel approaches for better efficacy, safety, and long-term tolerance.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

Illustrative Case Series and Narrative Review of Therapeutic Failure of Immunotherapy for Allergic Rhinitis

This is a series of 4 cases (3 therapeutic failure and 1 early relapse) in adult patients treated with allergen immunotherapy (AIT) for allergic rhinitis (AR) in our immunotherapy clinic, which treats 110 new patients per year. AIT includes both subcutaneous and sublingual routes. The current national/international AIT recommendations and the literature have been searched to identify guidance for the optimal management of therapeutic failure of AIT in AR. There is scant information available to support clinicians when treatment failure and/or intolerable side effects occur. The importance is highlighted for developing the guidance and evidence base for the benefit of this patient subgroup. The potential strategies that clinicians have proposed are discussed in this article, though it is acknowledged that these are mostly not evidence-based.

SCIT Versus SLIT: Which One Do You Recommend, Doc?

Allergic rhinitis is a prevalent condition that has a significant impact on the quality of life of many patients. When initial therapy fails to control the symptoms, allergen immunotherapy (AIT) has been suggested as an option by the Joint Task Force on Practice Parameters. The 2 main forms of AIT are via subcutaneous and sublingual routes, called subcutaneous immunotherapy and sublingual immunotherapy, respectively. There is debate about which is the better option for patients with each method offering its own pros and cons. We present 2 patients with allergic rhinitisAR that were deemed good candidates for AIT and explore current evidence for both subcutaneous immunotherapy and sublingual immunotherapy. The advantages and disadvantages of each method are discussed with the goal of providing a framework for the physician when deciding on AIT for their patients. In addition, we explore the use of AIT in patients with asthma and atopic dermatitis as potential patient populations that may benefit from the treatment. We use the discussion to provide recommendations regarding which method of AIT is best suited for both our patients.

Duration of Allergen Immunotherapy for Long-Term Efficacy in Allergic Rhinoconjunctivitis

RATIONALE

Subcutaneous and sublingual immunotherapy are effective for allergic rhinitis. An important question is whether allergen immunotherapy provides a sustained clinical effect after treatment cessation. In view of potential side effects, cost and the necessary patient commitment, long-term benefit is an important consideration for the recommendation of immunotherapy over standard pharmacotherapy.

PURPOSE OF REVIEW

In this review, we analyse the existing evidence for long-term effects of both routes of administration in the context of double-blind, placebo-controlled, randomised clinical trials that included a follow-up phase of at least 1 year after treatment cessation.

RECENT FINDINGS

Overall, evidence suggests that 3 years of either subcutaneous or sublingual immunotherapy result in clinical benefit and immunological changes consistent with allergen-specific tolerance sustained for at least 2-3 years after treatment cessation.

SUMMARY

The data presented here support recommendations in international guidelines that both routes of administration should be continued for a minimum of 3 years. Gaps in the evidence remain regarding the long-term efficacy of immunotherapy for perennial rhinitis and studies performed in children.

EAACI Guidelines on Allergen Immunotherapy: Allergic rhinoconjunctivitis

Allergic rhinoconjunctivitis (AR) is an allergic disorder of the nose and eyes affecting about a fifth of the general population. Symptoms of AR can be controlled with allergen avoidance measures and pharmacotherapy. However, many patients continue to have ongoing symptoms and an impaired quality of life; pharmacotherapy may also induce some side-effects. Allergen immunotherapy (AIT) represents the only currently available treatment that targets the underlying pathophysiology, and it may have a disease-modifying effect. Either the subcutaneous (SCIT) or sublingual (SLIT) routes may be used. This Guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on AIT for AR and is part of the EAACI presidential project "EAACI Guidelines on Allergen Immunotherapy." It aims to provide evidence-based clinical recommendations and has been informed by a formal systematic review and meta-analysis. Its generation has followed the Appraisal of Guidelines for Research and Evaluation (AGREE II) approach. The process included involvement of the full range of stakeholders. In general, broad evidence for the clinical efficacy of AIT for AR exists but a product-specific evaluation of evidence is recommended. In general, SCIT and SLIT are recommended for both seasonal and perennial AR for its short-term benefit. The strongest evidence for long-term benefit is documented for grass AIT (especially for the grass tablets) where long-term benefit is seen. To achieve long-term efficacy, it is recommended that a minimum of 3 years of therapy is used. Many gaps in the evidence base exist, particularly around long-term benefit and use in children.

Chamber and Field Studies demonstrate Differential Amb a 1 Contents in Common Ragweed Depending on CO₂ Levels

Although atmospheric carbon dioxide (CO₂) has no apparent direct effect on human health, it does have direct effects on plants. The present study evaluated the influence of increased CO₂ levels on the concentration of allergens from common ragweed pollen by setting up a chamber study to model future air conditions and a field study to evaluate current air conditions. For the chamber study, we established 20 ragweed plants in an open-top chamber under different CO₂ levels (380–400, 500–520, 600–620, and 1,000–1,100 parts per million [ppm]). For the field study, we established ragweed plants in rural (Pocheon, Gyeonggi-do; mean CO₂ 320±54.8 ppm) and urban (Gangnam, Seoul; mean CO₂ 440±78.5 ppm) locations. Seeds of the common ragweed (Ambrosia artemisiifolia) were obtained from Daejin University. The Amb a 1 protein content of pollen extracts was quantified using a double sandwich enzyme-linked immunosorbent assay. In our chamber study, the median concentration of Amb a 1 in pollen increased with increasing in CO₂ concentration (1.88 ng/µg in 380–400 ppm CO₂; 3.14 ng/µg in 500–520 ppm CO₂; 4.44 ng/µg in 600–620 ppm CO₂; and 5.36 ng/µg in 1,000–1,100 ppm CO₂). In our field study, we found no significantly different concentration of Amb a 1 between the pollen extracts at the Pocheon (mean±standard deviation, 1.63±0.3 ng/µg pollen in 320±54.8 ppm CO₂) and the Gangnam (2.04±0.7 ng/µg pollen in CO₂ in 440±78.5 ppm CO₂) locations, although the concentration of Amb a 1 was increased in the Gangnam than in the Pocheon locations. Our results suggest that future increases in CO₂ levels to more than 600 ppm will significantly elevate the Amb a 1 content in common ragweeds, although the current different CO₂ levels do not cause differences in the Amb a 1 content of ragweed pollen.

Is clinical tolerance possible after allergen immunotherapy?

There is a growing evidence that allergen immunotherapy (AIT) can provide significant and long-lasting clinical benefit for a number of allergic individuals. However, it is less clear if AIT results in clinical tolerance, which is characterized by a persistent state of clinical non-reactivity to allergens after therapy is finished. Addressing this knowledge gap is particularly relevant for patients undergoing AIT for food allergies, as anything less than complete tolerance could have potentially devastating consequences. An increasing number of studies, in particular those involving oral immunotherapy, are attempting to assess tolerance induction following AIT. Clinical tolerance does appear to be achievable in a subset of patients undergoing AIT, but whether this is equivalent to the type of tolerance observed in nonallergic individuals remains unknown. Developing established criteria for assessing tolerance induction, as well as the use of consistent terminology when describing clinical tolerance, will be important for determining the disease-modifying potential of AIT.

Sustained effect of grass pollen subcutaneous immunotherapy on suppression of allergen-specific basophil response; a real-life, nonrandomized controlled study

BACKGROUND

An important advantage of allergen immunotherapy as compared to pharmacotherapy for allergic rhinitis is the long-term effect that persists after completing immunotherapy. The mechanism of the sustained effect of allergen immunotherapy is not completely understood.

METHODS

We conducted a 7-year study of monitoring allergen-specific basophil response and serological markers in 20 subjects with moderate-to-severe grass pollen-allergic rhinitis just before beginning and after up-dosing of subcutaneous grass pollen immunotherapy, before the first pollen season, and 1-2 years after completion of 3-5 years of treatment. Comparable untreated rhinitis subjects were followed at the same time points. Clinical outcomes included assessment of symptoms, use of rescue medication, and quality of life. The basophil response was also monitored after removal of IgG antibodies.

RESULTS

Basophil response assessed as area under the curve (AUC) halved during initiation of SCIT and was 55% lower 1-2 years after completing SCIT. In the untreated group, the basophil response remained comparable. Although immunotherapy-induced grass pollen-specific IgG4 levels decreased to near pre-immunotherapy levels after completing SCIT, the removal of IgG antibodies resulted in an increase in basophil response almost to the pre-immunotherapy levels. In untreated subjects, removal of IgG did not have any effect on basophil response.

CONCLUSIONS

Grass pollen immunotherapy induces sustained suppression of the allergen-specific basophil response that persists after completion of treatment and could account for long-term clinical tolerance. It also seems to be associated with persistent blocking activity of IgG antibodies.

Recommendations for the standardization of clinical outcomes used in allergen immunotherapy trials for allergic rhinoconjunctivitis: an EAACI Position Paper

BACKGROUND

Allergen immunotherapy (AIT) has been thoroughly documented in randomized controlled trials (RCTs). It is the only immune-modifying and causal treatment available for patients suffering from IgE-mediated diseases such as allergic rhinoconjunctivitis, allergic asthma and insect sting allergy. However, there is a high degree of clinical and methodological heterogeneity among the endpoints in clinical studies on AIT, for both subcutaneous and sublingual immunotherapy (SCIT and SLIT). At present, there are no commonly accepted standards for defining the optimal outcome parameters to be used for both primary and secondary endpoints.

METHODS

As elaborated by a Task Force (TF) of the European Academy of Allergy and Clinical Immunology (EAACI) Immunotherapy Interest Group, this Position Paper evaluates the currently used outcome parameters in different RCTs and also aims to provide recommendations for the optimal endpoints in future AIT trials for allergic rhinoconjunctivitis.

RESULTS

Based on a thorough literature review, the TF members have outlined recommendations for nine domains of clinical outcome measures. As the primary outcome, the TF recommends a homogeneous combined symptom and medication score (CSMS) as a simple and standardized method that balances both symptoms and the need for antiallergic medication in an equally weighted manner. All outcomes, grouped into nine domains, are reviewed.

CONCLUSION

A standardized and globally harmonized method for analysing the clinical efficacy of AIT products in RCTs is required. The EAACI TF highlights the CSMS as the primary endpoint for future RCTs in AIT for allergic rhinoconjunctivitis.

Allergen immunotherapy for house dust mite: clinical efficacy and immunological mechanisms in allergic rhinitis and asthma

INTRODUCTION

There is an increasing prevalence of atopic diseases such as allergic rhinitis and asthma with house dust mite (HDM) being the common allergen that is highly associated with allergic rhinitis and asthma. Allergen avoidance and pharmacotherapy are part of treatment but it has proved difficult to change the course of HDM-related allergic diseases. Allergen immunotherapy (AIT) has been in use for the past century and has been shown to be effective in the treatment of allergic respiratory disease.

AREAS COVERED

This review exclusively focuses on HDM-AIT and discusses the differences in clinical efficacy and safety, long-term effect after discontinuation and immunological changes observed in both HDM-subcutaneous immunotherapy (SCIT) and HDM-sublingual immunotherapy (SLIT) in the treatment of allergic rhinitis and asthma in both pediatric and adult populations.

EXPERT OPINION

The majority of studies involved small numbers of patients, variable doses of major allergens and are of variable quality. There is good evidence for HDM-SCIT efficacy and its long-term effect in adults and children, whereas at the present time, evidence for HDM-SLIT is unconvincing, particularly in children. In carefully selected patients, HDM-SCIT is effective and safe. More definitive trials are needed before HDM-SLIT can be recommended in routine practice for rhinitis and/or asthma.

Effectiveness of subcutaneous immunotherapy for allergic rhinoconjunctivitis and asthma: a systematic review

OBJECTIVES/HYPOTHESIS

To systematically review the effectiveness and safety of subcutaneous immunotherapy (SCIT) for treatment of allergic rhinoconjunctivitis and asthma, using formulations currently approved in the United States.

STUDY DESIGN

We searched the following databases up to May 21, 2012: MEDLINE, Embase, LILACS, and the Cochrane Central Register of Controlled Trials.

METHODS

We included randomized controlled trials published in English comparing SCIT to placebo, pharmacotherapy, or other SCIT regimens that reported clinical outcomes of interest. Studies of adults or mixed age populations were included. Studies were excluded if the diagnosis of allergy and/or asthma was not confirmed with objective testing. Paired reviewers selected articles for inclusion and extracted data. We assessed the risk of bias for each study and graded the strength of evidence for each outcome as high, moderate, or low.

RESULTS

Sixty-one studies met our inclusion criteria. Majority of the studies (66%) evaluated single-allergen immunotherapy regimens. The literature provides high-grade evidence that SCIT reduces asthma symptoms, asthma medication usage, rhinitis/rhinoconjunctivitis symptoms, conjunctivitis symptoms, and rhinitis/rhinoconjunctivitis disease-specific quality of life in comparison to placebo or usual care. There is moderate evidence that SCIT decreases rhinitis/rhinoconjunctivitis medication usage. Respiratory reactions were the most common systemic reaction. There were few reports of anaphylaxis; no deaths were reported.

CONCLUSIONS

Generally moderate to strong evidence supports the effectiveness of SCIT for treatment of allergic rhinitis and asthma, particularly with single-allergen immunotherapy regimens. Adverse reactions to SCIT are common, but no deaths were reported in the included studies.

Allergen immunotherapy for allergic respiratory diseases

Allergen specific immunotherapy involves the repeated administration of allergen products in order to induce clinical and immunologic tolerance to the offending allergen. Immunotherapy is the only etiology-based treatment that has the potential for disease modification, as reflected by longterm remission following its discontinuation and possibly prevention of disease progression and onset of new allergic sensitizations. Whereas subcutaneous immunotherapy is of proven value in allergic rhinitis and asthma there is a risk of untoward side effects including rarely anaphylaxis. Recently the sublingual route has emerged as an effective and safer alternative. Whereas the efficacy of SLIT in seasonal allergy is now well-documented in adults and children, the available data for perennial allergies and asthma is less reliable and particularly lacking in children. This review evaluates the efficacy, safety and longterm benefits of SCIT and SLIT and highlights new findings regarding mechanisms, potential biomarkers and recent novel approaches for allergen immunotherapy.

Immunotherapy - Vaccines for allergic diseases

Allergic diseases are some of the most commonly encountered problems in clinical practice. Drugs such as corticosteroids and antihistamines can provide effective symptomatic relief, but do not alter the course of the disease. Specific immunotherapy (SIT) was first used to treat pollen allergy in 1911, and has since evolved into an effective treatment for allergic rhinitis and asthma. SIT has been shown in clinical studies to reduce symptoms and medication use in patients with allergic rhinitis and asthma. Recent studies also showed that the therapeutic benefit is long-lasting after the completion of three to five years of treatment. SIT can also effectively reduce the risk of developing asthma and new allergic sensitizations in children with allergic rhinitis.

The role of immunotherapy in the management of childhood asthma

Subcutaneous immunotherapy (SCIT) is still questioned as a safe and efficacious way of treating allergic asthma in children. In a Cochrane review published in 2010 it was, however, concluded that SCIT has significant and beneficial effects on symptoms and medication use in both children and adults with mostly mild asthma. Only a few studies have been performed to specifically study if SCIT in children with moderate asthma reduces the need for inhaled corticosteroids. There are conflicting results that illustrate the problem of the heterogeneity of the asthma disease and the fact that allergies may play different roles on the severity and symptoms of the disease. Furthermore, children with severe allergic asthma are often sensitized to multiple allergens, which makes SCIT both complicated and less safe to administer. On the other hand, if the child suffers from asthmatic symptoms despite adherence to pharmacotherapy, omalizumab or a combination of omalizumab and allergen immunotherapy might be useful. There is a need for more studies on this combination before it can be considered as an additional therapy in children with asthma and severe allergies. Sublingual immunotherapy (SLIT) has also been shown to improve asthma symptoms and medication use. SLIT is safe although its efficacy compared with SCIT has been studied very little. Another approach is to try to prevent asthma by treating children with SCIT for allergic rhinoconjunctivitis before asthma has developed. The most attractive prospect, however, is to find ways of preventing asthma by vaccination against the most common viruses, particularly rhinovirus. There is evidence that there are children at high risk of developing asthma in whom a viral infection can also enhance the risk of allergen sensitization. So far this vaccination has not been achievable although research is in progress.

Long-term clinical and immunological effects of allergen immunotherapy

PURPOSE OF REVIEW

The present review updates current findings on long-term clinical and immunological outcomes after cessation of allergen immunotherapy for allergic respiratory disease.

RECENT FINDINGS

Recent studies have shown that allergen immunotherapy has sustained disease-modifying effects that persist for years after discontinuation. This is in contrast to the effects of antiallergic drugs that do not induce tolerance to offending allergens. Long-term effects of immunotherapy include a reduction in nasal symptoms, a decrease in the use of rescue medication and improvement in quality of life. These benefits are accompanied by immunological changes such as the induction of allergen-specific IgG antibodies with inhibitory activity for IgE-facilitated binding of allergen-IgE complexes to B cells. One study reported a reduction in the development of asthma in children with seasonal pollen-induced rhinitis.

SUMMARY

Allergen immunotherapy induces clinical and immunological tolerance as defined by persistence of clinical benefit and associated long-term immunological parameters after discontinuation of treatment. These findings are largely confined to studies of subcutaneous and sublingual immunotherapy for seasonal pollinosis. Further studies are needed to address potential long-term clinical effects for other seasonal and perennial inhaled allergens in both children and adults, and to identify potential biomarkers of tolerance.

Sustained effects of grass pollen AIT

We report the sustained efficacy of the SQ-standardized grass allergy immunotherapy tablet Grazax® (Phleum pratense 75000 SQ-T/2,800 BAU, ALK, Denmark) from a 5-year randomized, double-blind, placebo-controlled phase III trial. Adults with moderate-to-severe grass pollen allergy inadequately controlled by symptomatic medications were followed for 2 years after the completion of 3 years of treatment. The active group demonstrated a 31% reduction in median rhinoconjunctivitis symptom score over the season compared with placebo. Individual symptom scores favoured active treatment. Combined symptom and medication scores demonstrated a 33% reduction in medians with active treatment. Persistent clinical efficacy was accompanied by prolonged increases in allergen-specific IgG(4) antibodies and IgE-blocking factor, confirming clinical and immunological tolerance for at least 2 years after the treatment completion. No safety issues were identified during follow-up.

Long-term clinical efficacy in grass pollen-induced rhinoconjunctivitis after treatment with SQ-standardized grass allergy immunotherapy tablet

BACKGROUND

Sustained and disease-modifying effects of sublingual immunotherapy have never before been confirmed in a large-scale randomized, double-blind, placebo-controlled trial.

OBJECTIVE

We sought to investigate sustained efficacy 1 year after a 3-year period of daily treatment with the SQ-standardized grass allergy immunotherapy tablet Grazax (Phleum pratense 75,000 SQ-T/2,800 BAU; ALK-Abelló, Hørsholm, Denmark).

METHODS

A randomized, double-blind, placebo-controlled, phase III trial including adults with a history of moderate-to-severe grass pollen induced rhinoconjunctivitis inadequately controlled by symptomatic medications. The analysis set comprised 257 subjects at the follow-up. Efficacy end points were rhinoconjunctivitis symptom and medication scores, quality of life, and percentages of symptom and medication free days. Immunologic end points included grass pollen-specific serum IgG4 and IgE-blocking factor. Safety was assessed based on adverse events.

RESULTS

Significant improvements in efficacy were consistently shown during 3 years' treatment. One year after treatment, the active group showed sustained reductions in mean rhinoconjunctivitis symptom scores (26%, P < .001) and medication scores (29%, P = .022) when compared with placebo. This level was similar to the efficacy observed during the 3-year treatment period. The differences in percentages of symptom- and medication-free days were significant during and 1 year after treatment. The active group also reported sustained and significant improvements in quality of life. Sustained clinical benefit was accompanied by immunologic changes. No safety issues were identified.

CONCLUSION

Three years of treatment with the SQ-standardized grass allergy immunotherapy tablet resulted in consistent clinical improvement and accompanying immunologic changes that were sustained 1 year after treatment, which is indicative of disease modification and associated long-term benefits.

Allergen-specific immunotherapy in allergic rhinitis and asthma. Mechanisms and proof of efficacy

Appeared at the beginning of the 20th century, allergen-specific immunotherapy (SIT) has long been used in allergic rhinitis and asthma without any knowledge of its mechanisms of action or any tangible proof of its efficacy. However, from the beginning of the era of evidence-based medicine, a number of placebo-controlled studies have been published and reached a sufficient number to assess the cellular events induced by SIT and allow meta-analysis to provide guidelines based on proofs. Controlled studies and meta-analysis concerned not only subcutaneous immunotherapy but also the sublingual route, demonstrating an effect of SIT on symptoms and medication use. Most recently sublingual tablets were proposed in allergic rhinitis. This paper reviews the mechanisms of SIT, the evidence of efficacy of SIT from the injective to the sublingual route and reminds the current guidelines.

Duration of allergen immunotherapy in respiratory allergy: when is enough, enough?

OBJECTIVES

To investigate the duration of effective inhalant subcutaneous immunotherapy (SCIT) reported in the published literature and to determine if any specific biomarkers or clinical predictors exist that may identify patients who will remain in long-term remission after discontinuing treatment.

DATA SOURCES

Articles were selected from a search of the PubMed database from 1976 to 2006 using the search terms immunotherapy and allergen immunotherapy in combination with venom, allergic rhinitis, asthma, mechanism, efficacy, and duration, as well as articles known to the authors and referenced in review articles.

STUDY SELECTION

Articles were selected if evaluation of efficacy of the primary allergic disease treated after discontinuation of SCIT was stated as one of the objectives of the study.

RESULTS

The rate of relapse after discontinuing SCIT ranges from 0% to 55% of patients in the studies reviewed in this article. The length of the specific allergen immunotherapy and allergen type (ie, perennial vs seasonal) may be variables that affect the duration of clinical remission after cessation of SCIT. One study found the duration of SCIT efficacy after discontinuation depended on duration of treatment and correlated with decrease in skin test reactivity.

CONCLUSION

Until specific tests or clinical markers are identified that will clearly distinguish between patients who will relapse from those who will remain in long-term clinical remission after discontinuing effective allergen immunotherapy, the decision to continue or stop immunotherapy must be individualized.

Allergen injection immunotherapy for seasonal allergic rhinitis

BACKGROUND

Allergic rhinitis is the most common of the allergic diseases. Despite improved understanding of the pathophysiology of allergic rhinitis and advances in its pharmacological treatment, its prevalence has increased worldwide. For patients whose symptoms remain uncontrolled despite medical treatment, allergen injection immunotherapy is advised. An allergen-based treatment may reduce symptoms, the need for medication and modify the natural course of this disease.

OBJECTIVES

To evaluate the efficacy and safety of subcutaneous specific allergen immunotherapy, compared with placebo, for reducing symptoms and medication requirements in seasonal allergic rhinitis patients.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2006), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), Pre-MEDLINE, KOREAMED, INDMED, LILACS, PAKMEDINET, Scisearch, mRCT and the National Research Register. The date of the last search was February 2006.

SELECTION CRITERIA

All studies identified by the searches were assessed to identify randomised controlled trials involving participants with symptoms of seasonal allergic rhinitis and proven allergen sensitivity, treated with subcutaneous allergen specific immunotherapy or corresponding placebo.

DATA COLLECTION AND ANALYSIS

Two independent authors identified all studies reporting double-blind, placebo controlled randomised trials of specific immunotherapy in patients with seasonal allergic rhinitis due to tree, grass or weed pollens. Two authors independently performed quality assessment of studies. Data from identified studies were abstracted onto a standard extraction sheet and subsequently entered into RevMan 4.2.8. Analysis was performed using the Standardised Mean Difference (SMD) method and a random-effects model; P values < 0.05 were considered statistically significant. The primary outcome measures were symptom scores, medication use, quality of life and adverse events.

MAIN RESULTS

We retrieved 1111 publications of which 51 satisfied our inclusion criteria. In total there were 2871 participants (1645 active, 1226 placebo), each receiving on average 18 injections. Duration of immunotherapy varied from three days to three years. Symptom score data from 15 trials were suitable for meta-analysis and showed an overall reduction in the immunotherapy group (SMD -0.73 (95% CI -0.97 to -0.50, P < 0.00001)). Medication score data from 13 trials showed an overall reduction in the immunotherapy group (SMD of -0.57 (95% CI -0.82 to -0.33, p<0.00001)). Clinical interpretation of the effect size is difficult. Adrenaline was given in 0.13% (19 of 14085 injections) of those on active treatment and in 0.01% (1 of 8278 injections) of the placebo group for treatment of adverse events. There were no fatalities.

AUTHORS' CONCLUSIONS

This review has shown that specific allergen injection immunotherapy in suitably selected patients with seasonal allergic rhinitis results in a significant reduction in symptom scores and medication use. Injection immunotherapy has a known and relatively low risk of severe adverse events. We found no long-term consequences from adverse events.

Long-lasting effects of sublingual immunotherapy for house dust mites in allergic rhinitis with bronchial hyperreactivity: A long-term (13-year) retrospective study in real life

BACKGROUND

Subcutaneous immunotherapy for respiratory allergy has shown a long lasting efficacy after its discontinuation, whereas evidence in the case of sublingual immunotherapy (SLIT) is weak. This retrospective study evaluates whether SLIT exerts a long-lasting effect and whether it relates to its duration.

METHODS

Sixty-five patients allergic to mite and positive to methacholine challenge 13 years ago were studied. Twelve (control group, SLIT 0) were treated for 4 years only with standard pharmacological therapy (SPT), while 53 received SLIT and SPT. Among these, four groups were identified according to SLIT duration. Fifteen patients were treated for 1 year (SLIT 1), 10 for 2 (SLIT 2), 14 for 3 (SLIT 3) and 14 for 4 years (SLIT 4). Clinical parameters (symptom monthly score, SMS), bronchial reactivity and FEV1 were evaluated in 1992 (run-in), 1993 (baseline) and every 2 years from 1997 to 2005.

RESULTS

Two to 3 years after the treatment ended, a positive effect on SMS, but not methacholine challenge and FEV1, was seen in the SLIT groups versus SLIT 0. At this time interval an effect on methacholine challenge was also seen in SLIT 3. After 7-8 years a significant difference was seen for SMS, i.e., it was significantly better in SLIT 4 than in the other groups, while bronchial reactivity was still improved in SLIT 1, 3 and 4 only after 5-6 years.

CONCLUSIONS

The effects of a 4-year SLIT on clinical parameters but not bronchial reactivity and FEV1 last 7-8 years after its discontinuation. SLIT shorter than 4 years yields proportionally less impressive results.

Long-term immunologic effects of broad-spectrum aeroallergen immunotherapy

BACKGROUND

Limited data exist regarding extended, long-term immunologic effects of immunotherapy in polysensitized individuals. To study possible long-term effects, skin tests and specific IgE levels were obtained from subjects who had previously received broad-spectrum aeroallergen immunotherapy years before.

METHODS

Eighty-two subjects (78% male, mean age 23 years) previously enrolled in a randomized, placebo-controlled trial of immunotherapy for treatment of childhood allergic asthma were reevaluated in adulthood (mean follow-up interval, 10.8 years) by puncture skin tests and CAP-RAST levels for major aeroallergens. All completed at least 18 months (median 27 months) of maintenance active treatment or placebo injections without subsequent immunotherapy.

RESULTS

At adult follow-up, 36% of all skin tests to treatment allergens among subjects who received immunotherapy (n = 41) had significantly reduced intensity versus 26% of skin tests among placebo recipients (n = 41; p = 0.03). No significant differences were noted for individual treatment allergens. No significant differences were observed in the long-term changes of serum-specific IgE antibody levels for all treatment allergens between immunotherapy treatment and placebo groups (p = 0.43). The treatment and placebo groups had a similar acquisition of new skin test sensitivities from time of randomization in the original childhood trial to debriefing (15 vs. 20%; p = 0.28) and to adult follow-up (30 vs. 31%; p = 0.75).

CONCLUSIONS

Immunotherapy suppresses skin test sensitivity 8-16 years after discontinuation of treatment, but long-term effects on specific IgE levels in serum are not observed. Broad-spectrum immunotherapy does not appear to affect the acquisition of new inhalant sensitivities.

Effect of pretreatment with fexofenadine on the safety of immunotherapy in patients with allergic rhinitis

BACKGROUND

Allergen-specific immunotherapy, although not a cure, remains the only treatment available that can alter the natural course of an allergic disease. However, the risk of allergen specific immunotherapy-related systemic reactions (SRs), reported to occur in approximately 1% to 14% of patients and which can range from mild to fatal in seriousness, represents a barrier to implementing this unique and effective treatment option.

OBJECTIVE

To explore the possibility that pretreatment with the H1-antihistamine fexofenadine could prevent the occurrence of severe SRs induced by immunotherapy in Japanese patients with allergic rhinitis.

METHODS

In this open-label, multicenter study, 134 patients receiving immunotherapy for allergic rhinitis were randomized 1:1 to a group receiving pretreatment with fexofenadine hydrochloride (60 mg) 2 hours before immunization injection (n = 67) or to a control group receiving no pretreatment (n = 67). Patients were further grouped into those who received cedar pollen immunotherapy and those who received dust mite immunotherapy.

RESULTS

Pretreatment with fexofenadine 2 hours before immunotherapy significantly reduced the occurrence of severe SRs (P = .03), significantly increased the proportion of patients receiving cedar pollen immunotherapy who achieved the target maintenance dose (TMD) (P = .03), and significantly reduced the length of time to attain the TMD (P = .047 and P = .003 for patients receiving cedar pollen and dust mite immunotherapy, respectively).

CONCLUSIONS

This study suggests a novel role for fexofenadine in enhancing the safety of immunotherapy and increasing the proportion of patients achieving the TMD.

Twelve-year follow-up after discontinuation of preseasonal grass pollen immunotherapy in childhood

BACKGROUND

In a previous controlled study, we demonstrated that preseasonal grass pollen immunotherapy for 3 years was effective in children. Moreover, a significant clinical benefit could still be observed 6 years after discontinuation of specific immunotherapy (SIT). In the current study, we examined the same group of patients again to investigate whether there is a prolonged benefit 12 years after SIT is stopped.

METHODS

Twenty-two patients with previous SIT (from 1989 through 1991) or standardized seasonal pharmacotherapy only were prospectively followed during the grass pollen season of 2003. Primary end points were symptom score, medication use, and combined symptom and medication score. In addition, skin prick test reactivity, development of new sensitizations, and prevalence of seasonal asthma were evaluated.

RESULTS

Total hay fever symptom score (P < 0.03), use of medication (P < 0.05), and combined symptom and medication score (P < 0.03) remained lower in patients with previous SIT when compared with the control group. Decreased immediate skin response to grass pollen returned 12 years after cessation of SIT. The percentage of new sensitization, however, continued to be significantly smaller in patients with previous SIT (58%) compared with the controls (100%, P < 0.05). There was a tendency for lower prevalence of seasonal asthma in the post-SIT group (P = 0.08).

CONCLUSION

This prospective controlled prolonged follow-up study demonstrates the ongoing clinical benefit 12 years after discontinuation of SIT. Furthermore, the reduction in onset of new sensitization, which was found 6 years after discontinuation of SIT, is sustained 6 years later.

Possible reasons for lack of effect of allergen avoidance in atopy-prone infants and sensitive asthmatic patients

The basic paradigm that allergen exposure produces atopic sensitization, and that continued exposure leads to clinical asthma throughout the development of airway inflammation and bronchial hyperreactivity has been challenged. However, because it was observed that epidemiological evidence suggests that around 40% of asthma cases are attributable to atopy (even using restrictive criteria), the obvious corollary is that if allergen avoidance begins before the onset of sensitization (primary prevention), then it should be associated with a reduced number of new cases of the disease. However, there are conflicting results regarding the effect of allergen avoidance on primary prevention of atopic sensitization and asthma onset. Instead, more uniform and positive results are available from secondary prevention studies. Secondary prevention obviously is an attractive opportunity for pediatricians who may recognize the patients who might benefit from these interventions simply by screening for food allergy in young children with atopic dermatitis. The conflicting results of tertiary prevention are most frequently observed in adult patients and sometimes result from incomplete avoidance of allergens responsible for the sensitization.

Efficacy and safety of subcutaneous immunotherapy with a biologically standardized extract of Ambrosia artemisiifolia pollen: a double-blind, placebo-controlled study

BACKGROUND

The allergological relevance of Ambrosia in Europe is growing but the efficacy of the injective immunotherapy for this allergen has been documented only in Northern America.

OBJECTIVE

We sought to study the safety and efficacy of injective immunotherapy in European patients sensitized to Ambrosia artemisiifolia.

METHODS

Thirty-two patients (18 M/14 F, mean age 36.78, range 23-60 years) suffering from rhinoconjunctivitis and/or asthma and sensitized to Ambrosia were enrolled and randomized in a double-blind, placebo-controlled (DBPC) study lasting 1 year. A maintenance dose corresponding to 7.2 microg of Amb a 1 was administered at 4-week intervals after the build-up. During the second and the third year, all patients were under active therapy in an open fashion. Symptom and medication scores, skin reactivity to Ambrosia (parallel line biological assay), and pollen counts were assessed throughout the trial.

RESULTS

Twenty-three patients completed the trial. No severe adverse event was observed. During the DBPC phase, actively treated patients showed an improvement in asthmatic symptoms (P=0.02) and drug (P=0.0068) scores days with asthmatic symptoms (P=0.003), days with rhinitis symptoms (P=0.05), and days with intake of drugs (P=0.0058), as compared to before therapy. No improvement for any of these parameters was detected in the placebo group. Moreover, the number of days with rhinitis and asthma was significantly higher in the placebo as compared to the active group (P=0.048 and P<0.0001, respectively). Patients who switched from placebo to active therapy improved in rhinoconjunctivitis, asthma, and drug intake. The skin reactivity decreased significantly (12.2-fold, P=0.0001) in the active group whereas a slight increase (1.07-fold, P=0.87) was observed in the placebo group after the DBPC phase. After switching to active therapy, patients previously under placebo showed a significant decrease of this parameter (4.78-fold, P=0.002).

CONCLUSION

Injective immunotherapy is safe and clinically effective in European patients sensitized to Ambrosia.

Allergen immunotherapy in the prevention of asthma

PURPOSE OF REVIEW

Asthma is a disease causing significant morbidity and mortality. In the recent past, there has been an explosion of pharmacotherapeutic options attempting to control the disease. Unfortunately, none of the current options offers the promise of prevention or a permanent cure. However, there appear to be exciting, new data emerging to support the hypothesis that the prevention or early treatment of allergic rhinitis, such as with the use of allergen immunotherapy, may help mitigate the severity of bronchial symptoms and even prevent the development of asthma. In this paper, we review recent research published proposing immunotherapy as a means of preventing the development of, or at least ameliorating, allergic asthma.

RECENT FINDINGS

There is evidence that the upper and lower airways may be considered a single unit, with the nasal and bronchial mucosa having features in common. Epidemiological, pathophysiological and clinical studies have shown that they can be affected by similar inflammatory triggers, with interconnected mechanisms amplifying the inflammatory cascade. Allergic rhinitis is interrelated to, and is a risk factor for, the development of asthma. An evidence-based review validates the successful use of allergen immunotherapy in treating allergic rhinitis and asthma. There is promising evidence advocating its use in the prevention of clinical asthma.

SUMMARY

This article explores current research pertaining to the use of immunomodulation, such as by using allergen immunotherapy, to ameliorate and prevent the development of allergic asthma.

Clinical efficacy of sublingual and subcutaneous birch pollen allergen-specific immunotherapy: a randomized, placebo-controlled, double-blind, double-dummy study

BACKGROUND

Both sublingual allergen-specific immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT) have a documented clinical efficacy, but only few comparative studies have been performed.

OBJECTIVE

To investigate the clinical efficacy of SLIT vs SCIT and secondary to compare SLIT and SCIT with placebo and to evaluate the relative clinical efficacy in relation to systemic side-effects.

METHODS

A 3-year randomized, placebo-controlled, double-blind, double-dummy study including 71 adult birch pollen hay fever patients treated for two consecutive years after a baseline year. Allocation to treatment groups was based on disease severity in the baseline season, gender and age.

RESULTS

Clinical efficacy was estimated in 58 patients completing the first treatment year by subtracting baseline data and by calculating the ratio first treatment season vs baseline. SLIT diminished the median disease severity to one-half and SCIT to one-third of placebo treatment. No statistical significant difference between the two groups was observed. Both for symptoms and medication scores actively treated patients showed statistically significant and clinical relevant efficacy compared with placebo. SLIT treatment only resulted in local mild side-effects, while SCIT resulted in few serious systemic side-effects.

CONCLUSION

Based on the limited number of patients the clinical efficacy of SLIT was not statistically different from SCIT, and both treatments are clinically effective compared with placebo in the treatment of birch pollen rhinoconjunctivitis. The lack of significant difference between the two treatments does not indicate equivalent efficacy, but to detect minor differences necessitates investigation of larger groups. Due to the advantageous safety profile SLIT may be favored.

25. Immunotherapy of allergic disease

Specific immunotherapy involves the administration of allergen extracts to achieve clinical tolerance of the allergens which cause symptoms in patients with allergic conditions. Immunotherapy has been shown to be effective in patients with mild forms of allergic disease, and also in those who do not respond well to standard drug therapy. Recent studies suggest that specific immunotherapy may also modify the course of allergic disease, by reducing the risk of developing new allergic sensitizations, and also inhibiting the development of clinical asthma in children treated for allergic rhinitis. Specific immunotherapy remains the treatment of choice for patients with systemic allergic reactions to wasp and bee stings. The precise mechanisms responsible for the beneficial effects of SIT remain a matter of research and debate. An effect on regulatory T cells seems most probable, associated with switching of allergen-specific B cells towards IgG4 production. Few direct comparisons of specific immunotherapy and drug therapy have been made. Existing data suggest that the effects of specific immunotherapy take longer to come on, but once established, specific immunotherapy will give long-lasting relief of allergic symptoms, whereas the benefits of drugs only last as long as they are continued.

Long-term and preventive effects of sublingual allergen-specific immunotherapy: a retrospective, multicentric study

There is now an increasing body of evidence to support the practice of allergen-specific sublingual-swallow immunotherapy (SLIT) in the treatment of IgE-mediated respiratory allergies. Recent studies on traditional injection therapy have pointed out that this form of treatment is not only capable to decrease actual allergic symptoms, but may also have long-term clinical and preventive effects and may influence atopy natural history. In the year 2000, our group published a retrospective, multicenter study showing the efficacy and safety of SLIT in a survey of 302 patients. We now carried out a second study on the same patients, with the aim of investigating long-term and preventive effects of SLIT. Beside the well-known safety and efficacy of this treatment (80.8% of patients reported clinical benefits), SLIT proved also to elicit long term clinical effects: over a mean follow-up of 11.6 months after the end of treatment, 80.8% of patients still maintained the previously achieved benefits. During the follow-up period, only 1% of non-asthma patients reported an onset of respiratory symptoms, and only 9.6% of patients undergoing new skin tests showed new sensitizations. All the clinical benefits were strongly linked to the length of treatment: patients with long-lasting benefits were treated for a mean length of 29.1 months, while patients showing a return to pre-SLIT condition were treated for a mean 13.3 months. SLIT can obtain long-term and preventive effects so far attributed to injection immunotherapy.

Long-term efficacy of preseasonal grass pollen immunotherapy in children

BACKGROUND

In a previous controlled study we demonstrated that preseasonal grass pollen immunotherapy for three years was effective in children. In the current study we examined the same group of patients to see if there is still a benefit six years after discontinuation of treatment.

METHODS

Thirteen of 14 patients with previous specific immunotherapy (SIT) and 10 out of 14 patients of the control group were prospectively followed during the grass pollen season. Outcome measures were seasonal symptom scores for eyes, nose and chest, the use of symptomatic medication and visual analog scale. Objective measures included skin prick test reactivity to seasonal and perennial allergens and conjunctival provocation testing.

RESULTS

During the 13 week observation time scores for overall hayfever symptoms (P < 0.004) and individual symptoms for eyes (P < 0.02), nose (P < 0.04) and chest (P < 0.01) as well as combined symptom and medication scores (P < 0.002) remained lower in the group with previous SIT. Only 23% of patients with previous pollen-asthma who had received SIT experienced pollen-associated lower respiratory tract symptoms compared to 70% in the control group (P < 0.05). There was no significant difference in the use of pharmacological treatment during the pollen season except for asthma medication. The average visual analog scale was lower in the post-SIT group (P < 0.05). Six years after cessation of SIT the immediate skin response to grass pollen remained decreased compared to the reaction of the controls (P < 0.01). There was also a tendency for higher allergen concentration to provoke a conjunctival response in the post-SIT group but without reaching statistical significance. Eight years after commencement of SIT, 61% of the initially pollen-monosensitized children had developed new sensitization to perennial allergens compared to 100% in the control group (P < 0.05).

CONCLUSIONS

There is still a significant clinical benefit six years after discontinuation of preseasonal grass pollen immunotherapy in childhood. SIT in children with pollen-allergy reduces onset of new sensitization and therefore has the potential to modify the natural course of allergic disease.