Introduction: Severe asthma is affecting 3-10% of the adult asthma population worldwide. In the last years biologic agents targeting IL-5/5R have been approved; their efficacy and safety have been evaluated in randomised controlled trials, which however are conducted under ideal conditions with strict inclusion and exclusion criteria.

Aim: We performed a systematic literature review in PubMed, in order to assess the effectiveness of anti-IL5/5R agents based on data from real-world observational studies.

Methods: We searched PubMed (until December 31st, 2022) for observational studies regarding anti-IL-5/5R biologics.

Results: The search resulted in 3542 studies, and after excluding studies in conference proceedings, RCTs, systematic reviews, meta-analyses and duplicates, 107 studies were evaluated, with 8,338 participants (45.4% female), mean age (SD) 48.3 (11.7) years. The distribution of the studies was: mepolizumab (74 studies-69.1%), benralizumab (29 studies-27.2%) and reslizumab (4 studies-3.7%). The following outcomes were available: FEV1 (81 studies-75.7%), exacerbations (76 studies-71%), hospitalisations (58 studies-54.2%), asthma control questionnaire (77 studies-71.9%), asthma quality of life questionnaire (71 studies-66.3%), oral corticosteroids reduction (72 studies-67.2%), FENO (35 studies-32.7%) and adverse events (42 studies-39.2%).

Conclusions: In this systematic review of observational studies on the effectiveness of anti-IL5/5R agents in severe asthma we have confirmed their efficacy in the treatment of the disease. More real-world studies are needed, especially for reslizumab, in order to assess and quantify their effectiveness rigorously.