Administration and Burden of Subcutaneous Immunotherapy for Allergic Rhinitis in U.S. and Canadian Clinical Practice

Allergy immunotherapy (AIT) is the only available treatment that alters the natural course of allergies and has possible disease-modifying effects. AIT is administered primarily via subcutaneous injection delivered in a physician's office. Few studies have been conducted in the United States or Canada to evaluate the costs of subcutaneous immunotherapy (SCIT).

To (a) describe SCIT administration processes, resources, and costs and (b) characterize the patient population receiving SCIT.

A multisite, prospective, observational time and motion study was conducted. Injection and wait times were collected by a third-party observer on 1 visit for each patient. Extract preparation processes were also observed. Site staff reported on treatment protocols, administrative time, supplies, and patient medical history. Patients responded to questionnaires on demographics, reasons for treatment, medication use, productivity, and travel time. Costs were estimated by applying unit costs to the time observations and the patient- and staff-reported data.

A total of 670 SCIT patients were enrolled at 6 sites in the United States and 6 sites in Canada. Average age in the United States was 41 years (SD = 18) and 44 years (15) in Canada, with 10% of the patients aged ≥ 65 years. Annual incomes were over $100,000 for 40% of U.S. patients and 30% of Canadian patients. U.S. patients had over 4 times as many different allergens in their SCIT treatments as Canadian patients, with a mean of 18 versus 4. The most common reasons reported for starting SCIT was a "desire to cure allergies once and for all" (73%) and that "symptoms are not improved by allergy medications" (60%). Percentages of patients taking allergy medications in the 4 weeks prior to observation were 86% in the United States and 66% in Canada: antihistamines 75% United States, 54% Canada; inhaled corticosteroids 32% United States, 22% Canada. The predominant comorbidity was asthma, 43% United States, 24% Canada. Site protocols for build-up treatment phases were 1 to 2 injections per week for an average of 25 weeks (range 12-52). Maintenance phases were 1 injection every 3 to 4 weeks for an average of 4 years (range 2.5-5). Eight of the sites had total mean staff times per injection visit of 7 to 22 minutes; 1 site averaged fewer minutes, and 3 sites averaged more. Total direct medical costs were an average of $30 for Canadian patients per visit and $32 per visit for U.S. patients, half accounted for by the cost of the extract. Pre- and postinjection administrative tasks were the second largest driver of direct costs. Total injection visit-related time for patients, including round-trip travel time, averaged about 80 minutes per visit in the United States and in Canada.

Analyses revealed substantial variation in SCIT regimens among sites, but the sites had commonalities in the injection process components. SCIT requires patient commitment to a long-term treatment regimen involving numerous clinic visits and resources for administration.