In the current (see page 360) and forthcoming issues of Thorax we are publishing a series examining current practice and evidence of the epidemiology and pathogenesis, prevention and treatment of pulmonary exacerbations in patients with cystic fibrosis (CF) and bronchiectasis.^1–,⁴ This follows on from a recent series examining aspects of exacerbations of chronic obstructive pulmonary disease and asthma. These reviews involved authors from Australia, USA and the UK, and each has considered the topics from both a paediatric and adult perspective. Several themes emerge in these reviews, including: (1) the challenges of diagnostic precision of definitions of respiratory exacerbations; (2) the need to develop new and/or novel endpoints for therapeutic trials for the treatment of exacerbations; and (3) the urgent need for multicentre studies to investigate both preventive and therapeutic interventions for patients with CF and bronchiectasis.

Goss and Burns highlight recent studies which have used definitions of pulmonary exacerbations in patients with CF.¹ While many of the multicentre studies have used formal definitions of exacerbations, all have included components which are subjective and have had only limited validation.^5,6 Even the role of objective clinical measures in the definition …