Bronchiectasis in Europe: data on disease characteristics from the European Bronchiectasis registry (EMBARC)

Background Bronchiectasis is a heterogeneous, neglected disease with few multicentre studies exploring the causes, severity, microbiology, and treatment of the disease across Europe. This aim of this study was to describe the clinical characteristics of bronchiectasis and compare between different European countries. Methods EMBARC is an international clinical research network for bronchiectasis. We report on a multicentre, prospective, observational, non-interventional, cohort study (the EMBARC registry) conducted across 27 European countries and Israel. Comprehensive clinical data were collected from adult patients (aged & GE;18 years) at baseline and annual follow-up visits using electronic case report form. Data from individual countries were grouped into four regions (the UK, northern and western Europe, southern Europe, and central and eastern Europe according to modified EU EuroVoc classification). Follow-up data were used to explore differences in exacerbation frequency between regions using a negative binomial regression model.Findings Between Jan 12, 2015, and April 12, 2022, 16 963 individuals were enrolled. Median age was 67 years (IQR 57-74), 10 335 (60 & BULL;9%) participants were female and 6628 (39 & BULL;1%) were male. The most common cause of bronchiectasis in all 16 963 participants was post-infective disease in 3600 (21 & BULL;2%); 6466 individuals (38 & BULL;1%) were classified as idiopathic. Individuals with bronchiectasis experienced a median of two exacerbations (IQR 1-4) per year and 4483 (26 & BULL;4%) patients had a hospitalisation for exacerbation in the previous year. When examining the percentage of all isolated bacteria, marked differences in microbiology were seen between countries, with a higher frequency of Pseudomonas aeruginosa and lower Haemophilus influenzae frequency in southern Europe, compared with higher H influenzae in the UK and northern and western Europe. Compared with other regions, patients in central and eastern Europe had more severe bronchiectasis measured by the Bronchiectasis Severity Index (51 & BULL;3% vs 35 & BULL;1% in the overall cohort) and more exacerbations leading to hospitalisations (57 & BULL;9% vs 26 & BULL;4% in the overall cohort). Overall, patients in central and eastern Europe had an increased frequency of exacerbations (adjusted rate ratio [RR] 1 & BULL;12, 95% CI 1 & BULL;01-1 & BULL;25) and a higher frequency of exacerbations leading to hospitalisations (adjusted RR 1 & BULL;71, 1 & BULL;44-2 & BULL;02) compared with patients in other regions. Treatment of bronchiectasis was highly heterogeneous between regions.Interpretation Bronchiectasis shows important geographical variation in causes, microbiology, severity, and outcomes across Europe.