The health economics of allergen immunotherapy

Effects of subcutaneous immunotherapy in allergic rhinitis children sensitive to dust mites

BACKGROUND

Subcutaneous immunotherapy (SCIT) is now the only treatment that can modify the natural course of allergic rhinitis (AR). However, not all children with AR benefit from SCIT.

OBJECTIVE

To evaluate the efficacy of SCIT in dust-mites-induced AR children and explore correlative factors predicting treatment response to SCIT.

METHODS

225 children aged 4-17 years old with AR were recruited from January 2016 to September 2019, and monitored at baseline, 4, 12, and 24 months after the start of SCIT treatment. The visual-analogue-score (VAS) was used to assess the clinical symptoms. Multivariate binary logistic regression analyses and receiver operating characteristic curves were used to explore correlative factors in predicting the efficacy of SCIT.

RESULTS

The significant declines in VAS started after 4 months of SCIT and continued to improve throughout the study compared with baseline. An increase in children's age (OR=0.688, 95%CI: 0.479-0.988) and those with allergic history (OR=0.097, 95%CI: 0.009-1.095) were negatively associated with the risk of poor efficacy. Polysensitized children were more likely to suffer poor efficacy (OR=15.511 95%CI: 1.319-182.355). The clinical response at month 4 (r=0.707) and month 12 (r=0.925) was related to that at month 24. The area under the curve (AUC) for improvement at month 4 and month 12 was 0.746 and 0.860, respectively.

CONCLUSION

Our study confirmed the clinical efficacy of SCIT in AR children. Children with younger age, negative allergic history, and multiple allergens may predict a worse efficacy. The onset of action and the clinical response to SCIT in the second year can be predicted as early as by month 4.

[Costs of allergic diseases and saving potential by allergen-specific immunotherapy : A personal assessment]

BACKGROUND

The burden of allergic diseases is of particular relevance for the economy and the social welfare and health insurance framework. Allergic rhinitis (AR) has a life-time prevalence of approximately 30% and is one of the most common chronic diseases with considerable socioeconomic impact thus leading to substantial direct, indirect and intangible costs. This article explores the common hypothesis that allergen-specific immunotherapy (ASIT) saves national economic expenses in the long term in comparison to other standard symptomatic treatment or no therapy.

METHODS

We conducted a selective search and analysis of the literature in PubMed and Medline including otherwise listed publications in German. Using a predefined model and data extrapolation over 9 years for data from different sources and short-term clinical studies we further discuss the problems and difficulties in analyzing heterogeneous datasets.

RESULTS

Using a health-economic model with currently available and accepted variables ASIT proves to be cost-effective in comparison to symptomatic treatment in allergic rhinitis; however, numerous parameters from other models have to be controlled, such as adherence to therapy and therapy discontinuation, heterogeneous costs for different treatment modalities, effect sizes with respect to symptoms including cross-influences with symptomatic rescue medication, duration of efficacy after treatment discontinuation and asthma protection.

DISCUSSION

The personal appraisal of the authors demonstrates not only the current knowledge but also the problems in health economical evaluation of ASIT in allergic diseases.

Fusion proteins consisting of Bet v 1 and Phl p 5 form IgE-reactive aggregates with reduced allergenic activity

The cross-linking of effector cell-bound IgE antibodies by allergens induces the release of inflammatory mediators which are responsible for the symptoms of allergy. We demonstrate that a recombinant hybrid molecule consisting of the major birch (Bet v 1) and grass (Phl p 5) pollen allergen exhibited reduced allergenic activity as compared to equimolar mixes of the isolated allergens in basophil activation experiments. The reduced allergenic activity of the hybrid was not due to reduced IgE reactivity as demonstrated by IgE binding experiments using sera from allergic patients. Physicochemical characterization of the hybrid by size exclusion chromatography, dynamic light scattering, negative-stain electron microscopy and circular dichroism showed that the hybrid occurred as folded aggregate whereas the isolated allergens were folded monomeric proteins. IgG antibodies raised in rabbits against epitopes of Bet v 1 and Phl p 5 showed reduced reactivity with the hybrid compared to the monomeric allergens. Our results thus demonstrate that aggregation can induce changes in the conformation of allergens and lead to the reduction of allergenic activity. This is a new mechanism for reducing the allergenic activity of allergens which may be important for modifying allergens to exhibit reduced side effects when used for allergen-specific immunotherapy.

Impact of increasing treatment rates on cost-effectiveness of subcutaneous immunotherapy (SCIT) in respiratory allergy: a decision analytic modelling approach

BACKGROUND

Specific immunotherapy is the only causal treatment in respiratory allergy. Due to high treatment cost and possible severe side effects subcutaneous immunotherapy (SCIT) is not indicated in all patients. Nevertheless, reported treatment rates seem to be low. This study aims to analyze the effects of increasing treatment rates of SCIT in respiratory allergy in terms of costs and quality-adjusted life years (QALYs).

METHODS

A state-transition Markov model simulates the course of disease of patients with allergic rhinitis, allergic asthma and both diseases over 10 years including a symptom-free state and death. Treatment comprises symptomatic pharmacotherapy alone or combined with SCIT. The model compares two strategies of increased and status quo treatment rates. Transition probabilities are based on routine data. Costs are calculated from the societal perspective applying German unit costs to literature-derived resource consumption. QALYs are determined by translating the mean change in non-preference-based quality of life scores to a change in utility. Key parameters are subjected to deterministic sensitivity analyses.

RESULTS

Increasing treatment rates is a cost-effective strategy with an incremental cost-effectiveness ratio (ICER) of 3484€/QALY compared to the status quo. The most influential parameters are SCIT discontinuation rates, treatment effects on the transition probabilities and cost of SCIT. Across all parameter variations, the best case leads to dominance of increased treatment rates while the worst case ICER is 34,315€/QALY. Excluding indirect cost leads to a twofold increase in the ICER.

CONCLUSIONS

Measures to increase SCIT initiation rates should be implemented and also address improving adherence.

Allergen immunotherapy for the treatment of respiratory allergies in the elderly

PURPOSE OF REVIEW

Respiratory allergies, including asthma and allergic rhinitis can also occur in the elderly. Allergen immunotherapy for allergic diseases is the only disease-modifying treatment for patients with allergies available thus far. Here, we review current evidence supporting the use of allergen immunotherapy in the elderly and discuss its efficacy and utility for the treatment of respiratory allergic diseases in this setting.

RECENT FINDINGS

Subcutaneous and/or sublingual immunotherapy are effective therapeutic options in not only young but also older patients. Allergen immunotherapy reduces medication and symptom scores in the elderly and can thus be safely prescribed in this population.

SUMMARY

Elderly individuals with proven, clinically relevant immunoglobulin E sensitization to inhalant allergens may benefit from allergen immunotherapy for respiratory allergic diseases. Older patients without contraindications should therefore be considered for treatment, with the additional benefit of reduced medication and symptom scores.

Persistence and evolution of allergen-specific IgE repertoires during subcutaneous specific immunotherapy

BACKGROUND

Specific immunotherapy (SIT) is the only treatment with proved long-term curative potential in patients with allergic disease. Allergen-specific IgE is the causative agent of allergic disease, and antibodies contribute to SIT, but the effects of SIT on aeroallergen-specific B-cell repertoires are not well understood.

OBJECTIVE

We sought to characterize the IgE sequences expressed by allergen-specific B cells and track the fate of these B-cell clones during SIT.

METHODS

We used high-throughput antibody gene sequencing and identification of allergen-specific IgE with combinatorial antibody fragment library technology to analyze immunoglobulin repertoires of blood and the nasal mucosa from aeroallergen-sensitized subjects before and during the first year of subcutaneous SIT.

RESULTS

Of 52 distinct allergen-specific IgE heavy chains from 8 allergic donors, 37 were also detected by using high-throughput antibody gene sequencing of blood samples, nasal mucosal samples, or both. The allergen-specific clones had increased persistence, higher likelihood of belonging to clones expressing other switched isotypes, and possibly larger clone size than the rest of the IgE repertoire. Clone members in nasal tissue showed close mutational relationships.

CONCLUSION

In the future, combining functional binding studies, deep antibody repertoire sequencing, and information on clinical outcomes in larger studies might aid assessment of SIT mechanisms and efficacy.

Subcutaneous Immunotherapy Improves the Symptomatology of Allergic Rhinitis

Introduction The relevance of allergic rhinitis is unquestionable. This condition affects people's quality of life and its incidence has increased over the last years.

Objective Thus, this study aims to analyze the effectiveness of subcutaneous injectable immunotherapy in cases of nasal itching, sneeze, rhinorrhea and nasal congestion in allergic rhinitis patients.

Methods In the present study, the same researcher analyzed the records of 281 patients. Furthermore, the researchers identified allergens through puncture cutaneous tests using standardized extracts containing acari, fungi, pet hair, flower pollen, and feathers. Then, the patients underwent treatment with subcutaneous specific immunotherapy, using four vaccine vials for desensitization, associated with environmental hygiene. The authors analyzed conditions of nasal itching, sneeze, rhinorrhea, and nasal congestion throughout the treatment, and assigned them with a score ranging from zero (0), meaning absence of these symptoms to three (3), for severe cases. The symptoms were statistically compared in the beginning, during, and after treatment.

Results In this study, authors analyzed the cases distribution according to age and the evolution of symptomatology according to the scores, comparing all phases of treatment. The average score for the entire population studied was 2.08 before treatment and 0.44 at the end. These results represent an overall improvement of ∼79% in symptomatology of allergic rhinitis in the studied population.

Conclusion The subcutaneous immunotherapy as treatment of allergic rhinitis led to a reduction in all symptoms studied, improving the quality of life of patients, proving itself as an important therapeutic tool for these pathological conditions.

Patient initiation and persistence with allergen immunotherapy

BACKGROUND

Allergen immunotherapy (AIT) is advised for patients with allergic rhinitis who remain symptomatic despite the use of pharmacotherapy and allergen avoidance. Several factors influence the decision to initiate and complete the AIT regimen.

OBJECTIVE

To evaluate patient initiation and persistence with subcutaneous and sublingual immunotherapies (SCIT and SLIT) according to physician recommendation.

METHODS

A retrospective review of electronic health records of patients with allergic rhinitis for whom AIT was recommended was conducted in a large private allergy practice in Pennsylvania.

RESULTS

Of 8,790 patients advised to consider AIT, 36.2% initiated AIT (57% adults, 43% children); 78% chose SCIT and 22% chose SLIT drops. Election of AIT was significantly associated with select comorbidities, specifically chronic sinusitis (8.1% for AIT vs 10% for no AIT), allergic conjunctivitis (12.5% for AIT vs 18.5% for no AIT), and asthma (33.8% for AIT vs 37.4% for no AIT; P < .05). Choice of SCIT vs SLIT drops was significantly associated with older age, female sex, select comorbidities, and more allergy medications at initiation (P < .05). Of adults, 30.2% completed at least 3 years of recommended treatment. Median time on treatment was longer for adults on SCIT vs SLIT drops (3 vs 1.6 years). Similarly, 35.4% of children completed treatment, with a longer median time on treatment for SCIT (4.7 years) vs SLIT drops (3.5 years).

CONCLUSION

A minority of patients initiated AIT according to allergist recommendation and a subset of these patients completed therapy. AIT might be an underused option that could benefit patients unable to manage allergic rhinitis symptoms by other means.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01549340.

Chapter 17: Immunomodulation of allergic sinonasal disease

IgE hypersensitivity is important to the pathogenesis of allergic diseases and the development and persistence of airway inflammation. Allergic immunomodulation encompasses various therapies that attempt to suppress or modify the immune mechanisms responsible for IgE-mediated disease. These include allergy immunotherapy (AIT) in the forms of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT), as well as the emergence of biological agents, such as anti-IgE, for allergic respiratory disease. Clinical evidence strongly supports the efficacy and safety of AIT for the treatment of allergic rhinitis, allergic conjunctivitis, and allergic asthma, but for chronic rhinosinusitis evidence is lacking. In allergic rhinitis, the decision to initiate AIT depends on the degree to which symptoms can be reduced by avoidance and medication, the amount and type of medication required to control symptoms, the adverse effects of medication, the severity and duration of symptoms, and their effect on quality of life. AIT has the potential to produce sustained long-lasting immune modulation and possibly avoid or reduce lifelong requirements for medical therapy. Although SLIT is currently being evaluated, SCIT remains the preferred form of AIT in the United States because of robust efficacy data, availability of allergen extracts, and current Food and Drug Administration approval. However, SLIT holds the potential for greater patient safety and convenience. Other immunomodulators such as anti-IgE also hold promise, but require further investigation.

[Role of allergen-specific immunotherapy (desensitization) for the treatment of allergies in Germany. Current situation]

Allergen-specific immunotherapy (SIT, desensitization) is applied monthly with subcutaneous injections (SCIT) or sublingually (SLIT) with droplets or tablets on a daily basis. Numerous immunological changes during SIT induce long-lasting tolerance. Efficacy has been demonstrated by a number of controlled studies for insect venom hypersensitivity (SCIT), allergic rhinoconjunctivitis (SCIT, SLIT particularly in grass pollen allergy), and allergic asthma (SCIT > SLIT). SIT is indicated in children and adults with severe allergic reactions from insect venoms (e.g., bee, wasp) or cumbersome symptoms from pollen, house dust mites or mold allergens and proven immediated-type allergy. Contraindications must be considered individually. SIT is performed for 3 years, in case of venom allergy 3-5 years. Severe systemic reactions are rare after SCIT. After SLIT rather local allergic symptoms of short duration occur in the mouth and throat. At present, the number prescriptions for SIT has decreased due to inadequate reimbursement of allergy-related services (diagnostics, therapies, monitoring). In the future, inferior medical care of allergic patients in Germany is expected, who until now have benefited from the preventive effects of SIT (reduced risk of developing asthma and new allergic sensitizations).

Can Serum-Specific IgE/Total IgE Ratio Predict Clinical Response to Allergen-Specific Immunotherapy in Children Monosensitized to House Dust Mite?

Background. Allergen-specific immunotherapy (SIT) is one of the important regimens for the treatment of allergic diseases. Predictive tests for the clinical response to SIT are limited. In this study we aimed to evaluate whether specific IgE/total IgE levels can predict clinical improvement in monosensitized patients to house dust mite treated with immunotherapy. Patients and Methods. We analyzed 32 patients who had undergone 2 years of SIT. Serum t-IgE and s-IgE levels, and serum s-IgE/t-IgE ratios were calculated and tested for correlation with clinical response to SIT. Asthma symptom score (ASS), rhinitis symptom score (RSS), pulmonary functions and visual analogue scales (VAS) were evaluated at the beginning and after 2 years. Results. There were 17 boys and 15 girls with the mean age of 10.78 ± 3.03 years. The mean serum house dust mite s-IgE level was 128.62 ± 142.61 kU/L, t-IgE 608.90 ± 529.98 IU/mL, and s-IgE/t-IgE ratio 33.83 ± 53.18. Before immunotherapy, ASS was 6.23 ± 1.63, RSS; 8.20 ± 1.88, VAS; 7.38 ± 2.01, FEV1 (%); 89.14 ± 8.48, PEF (%); 88.93 ± 13.57, and after 2 years, these values were determined as 1.90 ± 1.10, 3.05 ± 1.39, 1.35 ± 1.24, 97.6 ± 11.26, and 97.0 ± 11.55, respectively. s-IgE/t-IgE ratio was correlated with change in RSS (r = −0.392, P = 0.08) and VAS (r = −0.367, P = 0.05). Conclusion. Although SIT is very effective treatment, all patients do not benefit from treatment. We assumed that s-IgE/t-IgE ratio would be useful to predict the clinical response to SIT.

Analysis of allergen immunotherapy studies shows increased clinical efficacy in highly symptomatic patients

BACKGROUND

The assessment of allergen immunotherapy (AIT) efficacy in the treatment for seasonal allergic rhinoconjunctivitis (SAR) symptoms is challenging. Allergen immunotherapy differs from symptomatic therapy in that while symptomatic therapy treats patients after symptoms appear and aims to reduce symptoms, AIT is administered before symptoms are present and aims to prevent them. Thus, clinical studies of AIT can neither establish baseline symptom levels nor limit the enrolment of patients to those with the most severe symptoms. Allergen immunotherapy treatment effects are therefore diluted by patients with low symptoms for a particular pollen season. The objective of this analysis was to assess the effect possible to achieve with AIT in the groups of patients presenting the most severe allergic symptoms.

METHODS

Study centres were grouped into tertiles categorized according to symptom severity scores observed in the placebo patients in each centre (low, middle and high tertiles). The difference observed in the average score in each tertile in active vs placebo-treated patients was assessed. This allowed an estimation of the efficacy that could be achieved in patients from sites where symptoms were high during the pollen season.

RESULTS

An increased treatment effect was observed in the most severe patients and was independent of the study analysed and symptom score used.

CONCLUSIONS

The use of a tertile approach to analyse efficacy in AIT in SAR clinical studies can give a more accurate assessment of potential clinical benefit.