Acute exacerbations of bronchiectasis are critical determinants of disease progression and mortality. There is a need for practical biomarkers that can distinguish severity and predict prognosis to optimize care strategies. The advanced lung cancer inflammation index (ALI = BMI×serum albumin/neutrophil-to-lymphocyte ratio), a composite indicator for evaluating inflammation and nutrition, has shown potential in this regard. This study aimed to explore the association of ALI with exacerbation severity and clinical outcomes in bronchiectasis.

This observational, retrospective cohort study included 184 hospitalized patients with acute exacerbations of bronchiectasis. Eligible patients were grouped by ALI tertiles. The primary outcomes included bronchiectasis severity index (BSI), respiratory failure, and length of hospital stay.

ALI correlated inversely with C-reactive protein (rs = -0.55, P < 0.0001) and BSI scores (rs = -0.43, P < 0.0001) and positively with FEV1% predicted (rs = 0.25, P < 0.01) and FVC% predicted (rs = 0.29, P < 0.001). Multivariable Poisson and logistics analyses revealed that elevated ALI was independently associated with an decreased risk of respiratory failure, prolonged hospitalization and severe bronchiectasis. ALI outperformed its individual components in detecting severe bronchiectasis (AUC, 0.79; 95% CI, 0.70-0.87).

ALI is a simple biomarker that effectively reflects disease severity and the risk of poor clinical outcomes in patients with acute exacerbations of bronchiectasis. Its superior discriminative ability highlights its potential as a valuable tool for risk stratification and clinical management in this population.