Abstract
The concept of identifying patients who are likely to respond to specific treatments in asthma has evolved from the landmark studies of biologic therapies in asthma that targeted specific biomarker-related phenotypes. This targeted approach in randomized controlled trials (RCTs) provided the evidence required for the successful registration and use of a range of biologics in severe asthma. Subsequently, most authorities have mandated biomarker criteria relevant to the biologic target to align treatment with the evidence obtained from the RCTs. To improve the cost-effectiveness of such expensive medications, most funding authorities also mandate severity criteria for access. These include a history of frequent severe exacerbations requiring oral steroids or the use of continuous oral steroid therapy. A good response to biologic treatment is often a requirement for ongoing funding, with a reduction in severe exacerbations and oral corticosteroid (OCS) use being key outcomes used for this purpose.