Design: Multinational registry cohort, up to 5 years' follow-up
Population: 19,324 patients with bronchiectasis in 30 countries
Primary outcome: Future exacerbations and severe (hospitalised) exacerbations
Effect: IRR 1.45 (1 prior) to 3.56 (≥4 prior); severe exacerbation IRR 3.96 after 1 prior admission

The frequent exacerbator phenotype in bronchiectasis has been defined as three or more exacerbations a year. This analysis of 19,324 patients in the EMBARC registry, across 30 countries in Europe and Asia and followed for up to five years, asked how much each prior exacerbation adds.

The risk rose steadily. Compared with no exacerbations, the incidence rate ratio for future exacerbations was 1.45 (95% CI 1.34–1.58) after one, 1.84 after two, 2.50 after three and 3.56 (3.32–3.82) after four or more. A single prior hospitalised exacerbation was associated with a 3.96-fold rate of future severe exacerbations. The pattern held across causes and regions.

The cut-off of three was always arbitrary. These data suggest that one or two exacerbations — and especially one admission — should already prompt a review of airway clearance, sputum microbiology and long-term preventive therapy.

Record the number of bronchiectasis exacerbations in the past year at every review.
Treat a single hospitalised exacerbation as a strong warning sign for future admissions.
Review airway clearance technique and send sputum culture after even one or two exacerbations.
Consider long-term macrolide or inhaled antibiotic prophylaxis earlier than the traditional threshold of three.
In India, exclude post-tuberculous bronchiectasis and non-tuberculous mycobacteria before long-term macrolides.

Why it matters

It challenges the three-exacerbation threshold that gates access to preventive therapy.

The statistics, in plain English

An incidence rate ratio of 1.45 means about 45% more exacerbations in the following years than in someone with none. The risk rises step by step with no clear jump at three, which is why a single cut-off misrepresents it. This is registry data, so it describes risk rather than showing that earlier prevention helps.