Abstract
Recent advances in asthma research have led to the development of novel biologicals that hinder the pathological actions of key molecules in severe asthma. Traditional randomised controlled studies (RCTs), the gold standard for evaluating the efficacy and safety of medical interventions with excellent internal validity, have proven the clinical benefits and favourable safety profiles of type 2 biologicals in severe asthma. However, RCTs are not always ideal because of shortcomings such as limited external validity and practical issues in the management of severe asthma that cannot be solved through strictly designed clinical trials. Thus, the applicability of their findings may be questioned because treatment adherence is frequently poor in the real world. Real-world evidence includes a wide range of real-world data (RWD) collected from multiple sources in clinical practice, such as electronic medical records, healthcare insurance claims and retrospective or prospective patient registries. RWD may help clinicians decide how to manage patients with severe asthma. Real-world evidence is also gaining attention in addressing clinical questions not answered by traditional RCTs. Because there are various types of RWD with different possibilities and limitations, it is important to decide which type of RWD could be "fit for purpose" to address a specific question. This narrative review discusses the challenges and opportunities of RWD for evaluating the effectiveness and clinical outcomes of biological treatments for severe asthma.