Longitudinal performance of the bronchiectasis severity index (BSI) in patients on regular intravenous (IV) antibiotic therapy for bronchiectasis

Introduction: – The Bronchiectasis Severity Index (BSI) is a multi-dimensional tool that identifies risk of future mortality, admissions to hospital and exacerbations in patients with bronchiectasis. We aimed to investigate if the BSI reflects changes in the severity of bronchiectasis over time. Methods: – Retrospective cohort study of patients with bronchiectasis on long-term intravenous (IV) antibiotics. Demographic data and clinical parameters required for calculation of BSI were gathered. Results: – Fifteen patients on regular IV antibiotics were assessed over 1 year. Median age was 66 and 40% were male. Median BSI rose from 11 (IQR 9 – 13) to 12 (10.5 – 14.5)( p =0.12, Wilcoxon-Signed Rank test). BSI remained static in 1 (6.7%), decreased in 3 (20%) and increased in 11 (73.3%) patients. Improvements in BSI were due to reduction in the number of exacerbations and hospital admissions (2, 13.3%) or improvement in predicted FEV1 (1, 6.7%). Worsening BSI was attributable to decline in predicted FEV1 (3, 20%), admissions to hospital (2, 13.3%), Pseudomonas colonisation (2, 13.3%), colonisation with other organisms (1, 6.7%), increased number of exacerbations (1, 6.7%) increasing age (1, 6.7%) and increasing breathlessness (1, 6.7%). Conclusion: – The BSI is sensitive enough to detect changes in disease severity, particularly in hospital admissions, number of exacerbations, predicted FEV1 and bacterial colonisation. It thus has a potential role as a tool to monitor response to interventions in bronchiectasis. Further work with longer follow-up and a larger cohort of patients may demonstrate a statistically significant change in BSI.