Allergy immunotherapy utilisation

Allergy immunotherapy (AIT) is a treatment available to many Americans suffering from allergic rhinitis (AR), but before this study, there existed only limited evidence on both the burden of disease in patients receiving AIT, as well as the economic patterns behind the initiation of AIT. In this study patients were divided into three groups: 1. Any AIT claim, 2. Reaching maintenance defined by ≥25 injection claims for AIT, and 3. AR patients with no claims for AIT.

When comparing the full group of patients initiating AIT to patients diagnosed with AR not initiating AIT, it is seen that AIT patients on average had more health care claims associated with AR comorbidities in the 12-months leading up to AIT initiation than the non-AIT group in the year leading up to their first claim for AR. More than 20 comorbidities were selected as being related to AR. The proportion of AIT patients having a claim for an AR-related comorbidity at the time of initiation was higher for all AR-related comorbidities  ̶  including asthma, respiratory tract infection, eczema and chronic cough – compared to non-AIT (time of diagnosis of AR), i.e., indicating a greater burden of disease in AR patients initiating AIT.

Interestingly, in the 12 months following initiation of AIT, the patients, who reached the maintenance phase of treatment (≥25 injections), presented decreased rates of claims for all AR related comorbidities compared to observed rates during the 12-month pre-initiation period. This included eczema (-41%), chronic cough (-24%), and any upper respiratory tract infection (-10%). For all non-AIT AR patients, claims for AR-related comorbidities increased following their AR diagnosis, indicating a progression in disease.

Another finding was the reduction in the use of AR symptom-relieving medication. Among AIT patients reaching maintenance (≥25 injections), claims for antihistamines reduced by 6%, intranasal corticosteroids by 20%, and nasal spray by 20% for the year following AIT initiation.

In randomised clinical trials, the efficacy of AIT is often measured using a combined symptom and medication score as recommended by the European Medicines Agency (EMA). In real world evidence studies relying on data collected from routine clinical practice, the reduction in use of AR medication has often been used as a surrogate marker for effectiveness, as patient-reported symptoms are not collected in a structured way in routine clinical practice.

For patients reaching maintenance (≥25 injections), the study found that the number of patients with a claim for an emergency department (ED) visit related to AR reduced by 19% in the year following AIT initiation. On the other hand, patients in the non-AIT group had an increase in their AR-related ED visits of 42% in the year following their first diagnosis of AR, speaking to the progressive nature of AR.

When focusing on the costs for AIT patients reaching maintenance (≥25 injection), a decrease in AR-related costs for all service categories (inpatient costs, ED costs, doctor consultations, specialist consultations, laboratory costs, and other outpatient costs) is seen in the year following AIT initiation, except for ‘other outpatient costs’ which increased in the short term. This is where AIT treatment costs are captured, including consultation fees for allergy immunotherapy when administered as subcutaneous injections (SCIT, or allergy shots). This meant that total health care costs increased in the short term by on average USD 1,765, where the cost associated to treatment with AIT was USD 2,150 indicating cost offsets of USD 385 in other service categories.

For the non-AIT group on the other hand, increases were seen for all service categories. On average, total health care costs increased USD 677 from pre-diagnosis to the year following an AR diagnosis. This increase was primarily driven by physician office visit cost and other outpatient costs.

In this study, AIT patients were on average 34 years old (non-AIT 32 years old), with almost 25% of patients younger than 18 years old.  Approximately 58% were female (56% in non-AIT).

The comorbidity patterns indicate how AR is a progressive disease. Based on the comorbidities, AIT patients seem to be much more progressed in their disease, suggesting AIT is underutilised and seen as a last resort. This is supported by the fact that less than 5% of the current AR sample is initiating AIT.

Stone et al.; “Real-World Mapping of Allergy Immunotherapy in the United States: The Argument for Improving Adherence”, Allergy and Asthma Proceedings (2021)42:55-64. https://doi.org/10.2500/aap.2021.42.200114

Tkacz et al.; “Real-World Evidence Costs of Allergic Rhinitis and Allergy Immunotherapy in the Commercially Insured United States Population”, Current Medical Research and Opinion (2021)37(6):957-965. https://doi.org/10.1080/03007995.2021.1903848

EMA Guideline on the Clinical Development of Products for Specific Immunotherapy for the Treatment of Allergic Disease. CHMP/EWP/18504/2006