Factors Associated With Asthma Biologic Prescribing and Primary Adherence among Adults in a Large Health System

Background: The availability of asthma biologics may not benefit all patients equally. Objective: We sought to identify patient characteristics associated with asthma biologic prescribing, primary adherence, and effectiveness. Methods: A retrospective, observational cohort study of 9,147 adults with asthma who established care with a Penn Medicine asthma subspecialist was conducted using Electronic Health Record data from January 1, 2016, to October 18, 2021. Multivariable regression models were used to identify factors associated with (1) receipt of a new biologic prescription; (2) primary adherence, defined as receiving a dose in the year after receiving the prescription, and (3) oral corticosteroid (OCS) bursts in the year after the prescription. Results: Factors associated with a new prescription, which was received by 335 patients, included being a woman (odds ratio [OR] 0.66; P = .002), smoking currently (OR 0.50; P = .04), having an asthma hospitalization in the prior year (OR 2.91; P < .001), and having 4+ OCS bursts in the prior year (OR 3.01; P < .001). Reduced primary adherence was associated with Black race (incidence rate ratio 0.85; P < .001) and Medicaid insurance (incidence rate ratio 0.86; P < .001), although most in these groups, 77.6% and 74.3%, respectively, still received a dose. Nonadherence was associated with patient-level barriers in 72.2% of cases and health insurance denial in 22.2%. Having more OCS bursts after receiving a biologic prescription was associated with Medicaid insurance (OR 2.69; P = .047) and biologic days covered (OR 0.32 for 300–364 d vs 14–56 d; P = .03). Conclusions: In a large health system, primary adherence to asthma biologics varied by race and insurance type, whereas nonadherence was primarily explained by patient-level barriers.