Targeted literature review: epidemiology of severe and uncontrolled asthma and associated biomarkers in France, Germany, Italy, Spain and the UK

Abstract

<b>Introduction:</b> Severe and uncontrolled asthma are associated with high disease burden. Use of biological therapies in severe asthma is guided by the presence of specific biomarker levels. <b>Objective:</b> To summarize data on the prevalence of severe and uncontrolled asthma and associated biomarkers in France, Germany, Italy, Spain and the UK. <b>Methods:</b> We conducted targeted searches of Medline, Embase and websites of governmental bodies and asthma agencies. Included studies reported relevant data from patients with moderate to severe asthma in France, Germany, Italy, Spain or the UK. We primarily extracted data on severe asthma. A further search for biomarker data was conducted, with no restriction by asthma severity. <b>Results:</b> Among 29 relevant articles identified (EU [4], France [4], Germany [1], Italy [3], Spain [4], UK [13]), the reported asthma prevalence ranged from 5% (Germany) to ~8% (UK). Across studies, 4–20% of patients with asthma had severe asthma and up to 50% had uncontrolled asthma. Literature sources used different definitions of severity, making cross-study comparison difficult. In Italy, 59–71% of patients with severe asthma had ≥300 blood eosinophils/μL and 48–59% had fractional exhaled nitric oxide levels of ≥25 ppb. Of 363 558 patients in the UK, 0.8% had severe, uncontrolled eosinophilic asthma (≥300 blood eosinophils/µL). No high-quality data on biomarker prevalence in the other three countries were identified. <b>Conclusion:</b> Severe asthma prevalence varied by country. Further research using a standardized definition is needed on severe asthma prevalence and its phenotypes based on biomarker levels and other clinical attributes.