Real-world evaluation of severe asthma treatment Before and during the COVID-19 pandemic

Real-world studies add to the knowledge of severe asthma therapies by addressing issues within the heterogeneity of daily clinical practice, including its diverse patient population. In this way, real-world studies are complementary to traditional clinical trials, which take place in tightly controlled settings and include homogeneous patient populations. In the thesis several key real-world research questions regarding severe asthma treatment were addressed, relevant to the period before and during the COVID-19 pandemic. Issues addressed were for instance the harmful overuse of oral corticosteroids in asthma patients, the high prevalence of suboptimal use of inhaler therapy in these patients, and subsequent implications for the new targeted therapies for asthma (i.e. biologics). Furthermore, long-term therapy response to biologics targeting the interleukin (IL)-5 pathway was assessed, revealing that many patients still suffer from residual disease manifestations which were the main reasons for switches between anti-IL-5 biologics. Also, the safety of switching between biologics was explored. During the preparation of the thesis, the COVID-19 pandemic emerged, raising many new real-world research questions. For instance on the COVID-19 related risks for severe asthma patients, and the role for severe asthma therapies such as biologics. These issues were addressed in a review, editorial and original article, which used real-world data from the Dutch severe asthma registry “RAPSODI”. Finally, the impact of the pandemic on severe asthma care was investigated in a pan-European survey-based study. Thus, the thesis showed the valuable contribution of real-world studies to a wide variety of research questions related to severe asthma therapies.