Design: Multinational registry cohort
Population: 19,324 patients with bronchiectasis, 30 countries in Europe and Asia
Primary outcome: Future exacerbations and severe exacerbations over up to 5 years
Effect: IRR 1.45 (1 prior), 1.84 (2), 2.50 (3), 3.56 (≥4); prior admission and future severe exacerbation IRR 3.96 (95% CI 3.71–4.22)

This analysis of the EMBARC registry followed 19,324 patients with bronchiectasis across 30 countries in Europe and Asia for up to 5 years. It modelled how the number and severity of exacerbations in the previous year predicted later ones.

Risk rose with every exacerbation: the rate of future exacerbations was 1.45 times higher after one, 1.84 after two, 2.50 after three and 3.56 after four or more. A single exacerbation needing hospital admission was associated with nearly four times the rate of later severe exacerbations. The pattern held across causes and regions.

The old threshold of three exacerbations a year to define a frequent exacerbator is arbitrary. Even one or two exacerbations, and especially one admission, should prompt a review of airway clearance, sputum microbiology and long-term treatment.

Record exacerbations and admissions in the past year at every review
Treat one hospital admission as a marker of high risk
Review airway clearance technique and send sputum culture after any exacerbation
Consider long-term macrolide or inhaled antibiotics sooner rather than waiting for three events

Why it matters

It removes the idea of a safe number of exacerbations before prevention is stepped up.

The statistics, in plain English

Incidence rate ratios compare future exacerbation rates with patients who had none; 3.96 (95% CI 3.71–4.22) after a previous admission means roughly four times the rate of further severe exacerbations. These are associations in a registry and reflect prognosis, not the effect of any treatment.