Although widely accepted as an important treatment approach offering significant benefit to patients with environmental allergies, allergen immunotherapy (AIT) comes with the risk of severe allergic reactions and rare fatalities, explains Matthew Greenhawt, MD, MBA, MSc. “The pandemic has further complicated matters, now adding the risk of contracting COVID-19 to the potential downsides of requiring observed injections for every patient. For a study published in The Journal of Allergy and Clinical Immunology: In Practice, Dr. Greenhawt and colleagues sought to assess a model for patients who met the criteria to continue AIT treatment with home immunotherapy self-administration (HITSA). “While it is acknowledged that, in exceptional circumstances, some patients may receive allergy shots outside of a clinical setting, this is the first formal evaluation of health and economic benefits of such a practice, particularly during a pandemic,” adds Dr. Greenhawt.”From the patient perspective, it is important to consider direct and indirect risks of allergy shots, observed at a clinic or home. This analysis allows the physician to weigh options in the circumstance in which many patients may otherwise have their allergy shots deferred or suspended during the pandemic.”


Considering a New Method

To understand the cost-effectiveness of HITSA for AIT in an idealized patient group under shelter-in-place or other scenarios resulting in unforeseen reductions in nonessential medial services, the study team used Markov cohort evaluations and microsimulations, comparing HITSA with in-office AIT. Participants were randomly assigned to clinic-administered AIT with 30-minute observation, HITSA, or provider-directed AIT discontinuation. Patients receiving HITSA were instructed to maintain two epinephrine autoinjectors (EAIs), and those experiencing a systemic reaction to immunotherapy (SRIT) were transitioned to a required EAI strategy with clinic-administered AIT. The study team developed criteria for HITSA qualification, including having been advised of the risks and benefits and provided informed consent, no history of previous SRIT, no comorbidities complicating anaphylaxis severity and/or treatment, high health literacy, and appropriate education on storage, handling, and administration of AIT.


Cost-Effectiveness & Patient Circumstances

HITSA was found to be cost-effective— with an incremental cost-effectiveness ratio of $44,554/quality-adjusted life-year—when considering both incremental EAI costs and COVID-19 risks. HITSA was estimated to cost $16,464, compared with $16,394 for in-clinic AIT, and $18,332 for AIT discontinuation. “HITSA is a cost-effective option associated with the highest net monetary benefit under our base assumptions,” notes Dr. Greenhawt. “By eliminating EAI costs, HITSA was even more cost-effective, at $15,210, compared with clinic AIT costs of $16,283.” However, outside of pandemic considerations, HITSA was not cost-effective, with an incremental cost-effectiveness ratio of nearly $2 million at annual EAI costs above $287.

When assessing the net monetary benefits associated with simple changes in the assumptions of the model, the researchers found how fickle some assumptions can be, explains Dr. Greenhawt (Figure). “The figure highlights how the rate of risk of COVID contraction and fatality, one’s hourly wage, rate of allergic reactions from AIT, AIT fatality risks, and particular costs of care all help contribute to the chances that HITSA  is or is not cost effective,” he adds.

The model suggests that HITSA can be a viable option for certain patients, especially in unprecedented circumstances. “In select contexts for patients without prior SRIT and with high health literacy, HITSA can be safe and cost-effective,” says Dr. Greenhawt. “In understanding the risk to safety proposition with HITSA and what we may be asking our patients to trade-off, this may be a feasible alternative to in-office injections for some patients, both in the pandemic and beyond. It can be beneficial during service disruptions and could be a way to increase access to a valuable and helpful therapy.”


Evolving & Innovating

“In the practice of medicine, everything can and will evolve,” notes Dr. Greenhawt. “Sometimes, it takes moments like this pandemic to drive change and reconsider best practices. Without knowing what the future may hold, we need out-of-the-box thinking to continue innovating how to deliver patient care.”