Defining severity in non-cystic fibrosis bronchiectasis.

Bronchiectasis is a common disease with important impacts on patient's quality of life and on healthcare systems in terms of healthcare costs, hospitalisations and mortality. After decades of being regarded as an orphan disease there are an increasing numbers of treatments available, or in late-stage clinical trials. Assessment of disease severity is fundamental to clinical management. To date, however, there is no agreed definition of what constitutes mild, moderate or severe bronchiectasis. These terms are often applied to radiological appearances, but while important, computed tomography findings are not sufficiently precise to capture the complex impact of the disease. Studies are beginning to define the risk factors for mortality, hospital admissions, exacerbations and impaired quality of life in bronchiectasis, allowing us to propose new definitions of what constitutes severe bronchiectasis. An improved understanding of severity and prognosis in this disease will aid clinical decision making and the application of new therapies.

The bronchiectasis severity index. An international derivation and validation study.

RATIONALE: There are no risk stratification tools for morbidity and mortality in bronchiectasis. Identifying patients at risk of exacerbations, hospital admissions, and mortality is vital for future research. OBJECTIVES: This study describes the derivation and validation of the Bronchiectasis Severity Index (BSI). METHODS: Derivation of the BSI used data from a prospective cohort study (Edinburgh, UK, 2008-2012) enrolling 608 patients. Cox proportional hazard regression was used to identify independent predictors of mortality and hospitalization over 4-year follow-up. The score was validated in independent cohorts from Dundee, UK (n = 218); Leuven, Belgium (n = 253); Monza, Italy (n = 105); and Newcastle, UK (n = 126). MEASUREMENTS AND MAIN RESULTS: Independent predictors of future hospitalization were prior hospital admissions, Medical Research Council dyspnea score greater than or equal to 4, FEV1 < 30% predicted, Pseudomonas aeruginosa colonization, colonization with other pathogenic organisms, and three or more lobes involved on high-resolution computed tomography. Independent predictors of mortality were older age, low FEV1, lower body mass index, prior hospitalization, and three or more exacerbations in the year before the study. The derived BSI predicted mortality and hospitalization: area under the receiver operator characteristic curve (AUC) 0.80 (95% confidence interval, 0.74-0.86) for mortality and AUC 0.88 (95% confidence interval, 0.84-0.91) for hospitalization, respectively. There was a clear difference in exacerbation frequency and quality of life using the St. George's Respiratory Questionnaire between patients classified as low, intermediate, and high risk by the score (P < 0.0001 for all comparisons). In the validation cohorts, the AUC for mortality ranged from 0.81 to 0.84 and for hospitalization from 0.80 to 0.88. CONCLUSIONS: The BSI is a useful clinical predictive tool that identifies patients at risk of future mortality, hospitalization, and exacerbations across healthcare systems.