Subcutaneous and Sublingual Immunotherapy Cost-effective for Children With House Dust Mite Allergic Asthma

Results of a study published in Allergy: European Journal of Allergy and Clinical Immunology and based in Portugal showed subcutaneous (SCIT) and sublingual immunotherapy (SLIT) tablets to be more cost-effective than the standard of care (SOC) treatment in children with house dust mite-driven (HDM) allergic asthma.

Researchers aimed to compare the cost-effectiveness of SCIT and SLIT tablets in children with HDM allergic asthma to the SOC treatment within the context of the Portuguese health care system. The SOC treatment involves prescribing an inhaled corticosteroid (ICS) plus long-acting beta-agonists (LABA). AIT induces allergen-specific immune tolerance and therefore may aid in children with HDM allergic asthma. Studying the cost-effectiveness of AIT in children is necessary to inform clinical and policy-making decisions, the researchers said.

Researchers developed a hypothetical Markov model in order to compare the cost and health outcomes of SCIT and SLIT tablets with the SOC treatment in Portuguese children with HDM allergic asthma. The Markov model was based on the Global Initiative for Asthma (GINA) severity steps, which defined the health states of patients with asthma. A hypothetical cohort of 1000 children aged 12 years was created for each strategy (SCIT, SLIT, and SOC treatment) to compare them over a 10-year period divided into cycles of 6 months.

Cost-effectiveness was determined by calculating the incremental cost-effectiveness ratio (ICER). ICER was calculated by dividing incremental costs by incremental quality-adjusted life-years (QALYs) with the SOC treatment as the reference.

The ICER for the SCIT tablets was 1281€ gained per QALY compared with the SOC strategy. The ICER for the SLIT tablets was 771€ gained per QALY compared with the SOC strategy. Per patient, the incremental cost for SCIT tablets was 438€ with an incremental QALY of 0.342. The incremental cost for SLIT tablets per patient was 1021€ with an incremental QALY of 0.132. Both treatment strategies were below the cost-effectiveness threshold for Portugal of 18,482.80€.

The effect of AIT on reducing moderate and severe exacerbations and asthma controller medication was a major contributor to the study results. For SCIT, researchers estimated a reduction of 1898 moderate exacerbations and 45 severe exacerbations with a cost difference of 242,304€ and 125,542€, respectively. For SLIT, researchers estimated a reduction of 764 moderate exacerbations and 12 severe exacerbations.

A sensitivity analysis was conducted to assess the model they developed. SCIT had a higher probably of being cost-effective than SLIT did. For a cost-effectiveness threshold for Portugal of 20,000€, the probability of being cost-effective was 99% for SCIT and 75% for SLIT.

Researchers evaluated other scenarios as well in order to strengthen the results of their model. None of the ICER values reached the cost-effectiveness threshold. One of the alternative scenarios evaluated included allergic rhinitis as a comorbidity for children with asthma. This resulted in markedly reduced ICER values, especially for the SCIT strategy.

While the model in this study was applied to Portugal, the researchers note that the model is adaptable to other settings by changing parameters based on data from that setting. Other limitations include the fact that Markov models are dependent on previous data and therefore some parameters used in creating the model led to large variations in ICER values. This study did not include nonmedical costs, which may have effects ICER estimates.

Study results showed both SCIT and SLIT to be cost-effective when compared to the SOC treatment. “However, SCIT showed more consistent results and seemed to have a greater impact on clinical and quality of life outcomes by reducing exacerbations leading to emergency department visits and medication requirements,” the researchers concluded.

Reference

Farraia , Paciência I, Mendees FC, et al. Cost-effectiveness analysis of house dust mite allergen immunotherapy in children with allergic asthma. Allergy: Eur J Allergy Clin Immunol. Published online April 22, 2022. doi: 10.1111/all.15321