Adherence to Subcutaneous Allergen Immunotherapy Is Suboptimal

Brandon May

November 07, 2022

A recent systematic review of real-world data that was published in the International Forum of Allergy and Rhinology shows that persistence and adherence to subcutaneous allergen immunotherapy is suboptimal, suggesting that many patients with allergic rhinitis who are treated with this therapy may not achieve long-term disease control.

In an email to Medscape Medical News, study investigator Sandra Y. Lin, MD, of the University of Wisconsin School of Medicine, explained that subcutaneous immunotherapy (SCIT) is not only helpful for the control of allergic rhinitis symptoms but can also provide long-term relief years after the therapy has been completed. "However, to maximize the chances of benefiting from long-term symptom control, patients need 3 to 5 years of regular injections," she said.

Edwin H. Kim, MD, a pediatric allergist and immunologist and associate professor at the University of North Carolina School of Medicine, in Chapel Hill, explained that for some patients with allergic rhinitis, SCIT can provide long-term resolution of symptoms.

"But in order for us to try to achieve those longer lasting benefits, we really need patients to stay on therapy for an extended period of time to actually make those changes to the immune system, which would be probably the number one reason that the adherence would be important to us," Kim, who wasn't involved in the study, said by phone.

Real-World Studies Assessed

The systematic review by Lin and colleagues focused on real-world studies reporting on SCIT adherence and persistence. The authors defined adherence as "persistence in accordance with prescribed SCIT dose, dosing schedule, and duration." They defined persistence of SCIT as continuation of therapy and not being lost to follow-up after treatment initiation.

A total of 17 real-world studies with 263,221 patients with allergic rhinitis met the inclusion criteria and were subsequently reviewed by the investigators. Studies included in this review enrolled children and adults ranging in age from 1 to 90 years. Ten studies were conducted in the United States. Other geographic locations included the Netherlands, Kuwait, Denmark, Turkey, Italy, and South Korea.

Rates of SCIT persistence in the 14 studies that reported these rates ranged from 16.0% to 93.7%. In the seven studies that reported on adherence, rates of adherence to SCIT ranged from 15.1% to 99%.

The researchers suggest that the wide ranges reported in these studies may in part be due to differences in demographic characteristics, including age and type of insurance coverage.

For instance, the researchers note that US Medicare or Medicaid patients may be less adherent to SCIT than patients who have insurance from commercial payers. The reasoning behind this association was not explained by the researchers.

In three studies, patient-reported reasons for treatment discontinuation included inconvenience related to therapy, such as injection frequency and frequency of hospital visits. Another study reported local side effects as the most common reason for lack of adherence. Summarizing previous research, Lin commented that problems with insurance coverage represent another primary reason why patients discontinue therapy.

Given that SCIT often involves an in-office monitoring period, some patients with work commitments or other commitments may find this therapy inconvenient, according to Kim. He noted that clinics who manage patients with allergic rhinitis with SCIT should offer more treatment times that are convenient to patients.

"Whether this means office hours outside of regular business hours or office hours on the weekend," he said, "this is an important step to trying to make it easier for patients."

Lin added that clinicians should be diligent in monitoring adherence to subcutaneous allergen immunotherapy, as this could help to better "understand and hopefully address barriers to continuing treatment."

Kim also noted that clinicians could start treatment by setting expectations with patients, many of whom are looking for immediate relief from symptoms.

"If they go in with that expectation, they will be disappointed, because it really is more of a longer-term treatment and a longer-term benefit that they achieve," he said. "If we have patients that are more educated on the expected timeline of benefit, it may help them understand the importance of staying on the regimen."

The study received no industry funding. Lin and Kim report no relevant financial relationships.

Int Forum Allergy Rhinol. Published online September 9, 2022. Full text

Brandon May is a freelance medical journalist who has written more than 900 articles for medical publications in the United States and the United Kingdom. He resides in downtown Brooklyn, New York City. Twitter: @brandonmilesmay.

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