Purpose: Patients with severe asthma (SA) experience significant morbidity, due to high exacerbation rates and frequent use of oral corticosteroids (OCS). In randomized trials, biologic therapies (biologics) consistently improve SA outcomes. Using pharmacy claims data, the AUBOCIAS study estimated OCS use before and after initiation of biologics, and yearly trend of biologics use among SA patients.

Procedures: Anonymized dispensation data from pharmacies (IQVIA Switzerland LRx network) were retrieved between 2018 and 2023. SA patients aged ≥12 were identified by regular use of fixed-dose combinations over ≥12 months, or OCS, or any biologics used for SA. Main outcome was the change in total annual dose (TAD) of OCS after initiation of biologics.

Main findings: In 2023, among a total of 26,146 patients with likely asthma, 3882 (10.6 %) were identified as having SA. The mean age was 61 years and 57.0 % were females. Of those 63.0 % were using OCS, with a mean TAD of 1760 mg. Initiations of biologics for SA increased from 0.4 % (2018) to 14.3 % (2023). Over the study period, among 532 biologics initiators, 282 (53.0 %) used OCS: 87 patients (36.0 %) could be weaned (p < 0.0001). Among persistent OCS users, the mean TAD decreased from 1200-375 mg (-68.8 %; p < 0.0001).

Conclusions: In Switzerland, 10.6 % of patients with likely asthma identified in the LRx database were considered to have SA. OCS were frequently used at high TAD, while biologics were increasingly initiated. Most biologics initiators were able to reduce or discontinue OCS.