Adherence and outcomes among patients with moderate-to-severe asthma prescribed biologics

Published: May 28, 2022

Asthma biologic therapy is a relatively new treatment for patients with moderate-to-severe asthma. However, details of adherence to this type of asthma therapy remain unclear. Biologics differ from typical asthma medications. For example, asthma biologic therapy is for individuals with greater asthma severity, cost relatively more than traditional therapy, and have different mechanisms of delivery (injectable or intravenous infusion), with differing administration settings and frequency of administration. Therefore, adherence barriers may not be uniform for patients on asthma biologics.

The 3 aims examined in a recent Journal of Allergy and Clinical Immunology: In Practice article by Osazuwa-Peters and colleagues are as follows: first, they described differences in the characteristics of patients with moderate-to-severe asthma on biologic therapy by biologic therapy administration setting (Home, Clinic-only, and Hybrid); second, the investigators examined factors associated with asthma biologic adherence by administration setting; lastly, they assessed whether adherence to asthma biologic therapy was associated with 1-year emergency department (ED) visits.

Osazuwa-Peters et al used a database of commercially and publicly insured enrollees to identify a cohort of patients who had not previously started asthma biologics. They included individuals if, between January 1, 2015, to April 30, 2020, they had at least 1 pharmacy claim for asthma biologics. Patients were required to have continuous medical and prescription insurance coverage 6 months before and after their index date (when they first filled their prescription). The investigators measured adherence for 6 months starting from index date. The authors categorized patients by their biologic administration setting based on (a) solely medical claims (Clinic-only), (b) pharmacy claims only (Home), or (c) both medical and pharmacy claims (Hybrid). Then they calculated days supply per pharmacy claim as the difference between fill end date and adjusted fill date.

Two main outcomes were examined. The first outcome was estimated biologic adherence, expressed as the number of observed biologic doses administered divided by the number of brand-specific expected biologic dose administrations within the follow-up period. The second outcome considered was an all-cause emergency department visit up to one year from the day after the end of follow-up for adherence

There were 3,932 patients with moderate-to-severe asthma started on asthma biologic therapy who met the study inclusion criteria. Biologics adherence was 0.75 in Clinic setting, the most common administration setting, and 0.83 in both Home and Hybrid settings. Specialist access was consistently associated with better biologic adherence, whereas Black race, Hispanic ethnicity, lower education, Medicare only insurance, and higher patient out-of-pocket cost were associated with worse biologic adherence in some settings. Home and Hybrid patients were distinct from Clinic-only patients, being relatively older, with at least 70% on Medicare insurance types, and having a higher burden of comorbidities as well as significantly higher patient cost for either index biologics or total patient cost for all medications during the prior 6 months. In the Hybrid setting, hazard for a 1-year all-cause ED visit decreased with biologic adherence.

Asthma biologic adherence varies with administration setting, with lowest rates in the Clinic setting, whereas racial and ethnic as well as insurance-related disparities were apparent among patients who self-administer.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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