Validation of the Bronchiectasis Severity Index in alpha-1 antitrypsin deficiency

Bronchiectasis is increasingly recognised in patients with alpha-1 antitrypsin deficiency (AATD), yet prognostic tools validated in general bronchiectasis populations have not been specifically evaluated in this group. The Bronchiectasis Severity Index (BSI) is a widely used multidimensional score predicting mortality, hospitalisation, and exacerbations in all-cause bronchiectasis. This study aimed to validate the BSI in a cohort of patients with AATD-bronchiectasis. Clinical data were obtained from the Birmingham AATD registry. Patients with severe AATD genotypes and CT-confirmed bronchiectasis were included, while those with non-severe genotypes or alternative causes of bronchiectasis were excluded. BSI scores were calculated using available registry data with minor adjustments reflecting the limitations of cross-sectional data collection. Associations between BSI and mortality were assessed using Kaplan–Meier survival analysis and Cox proportional hazards models adjusted for COPD, smoking status, and sex. Secondary analyses evaluated associations between BSI and lung function decline (FEV 1 and KCO) and health-related quality of life (SGRQ). A total of 198 patients were included (mean age 54.3 ± 9.7 years; 53.5% male), the majority with the ZZ genotype (97.5%) and coexisting COPD (87.4%). Median BSI score was 5 (range 0–14). Mortality differed significantly across BSI severity groups (p 1 decline or SGRQ score. The Bronchiectasis Severity Index is associated with mortality risk in patients with AATD-associated bronchiectasis, supporting its use as a prognostic tool in this population. These findings provide evidence that a severity score derived from all-cause bronchiectasis cohorts can be applied to AATD, although prospective validation in larger multicentre datasets is warranted.