An International ISHLT/ATS/ERS Clinical Practice Guideline: Diagnosis and Management of BOS after Lung Transplant

Chronic lung allograft dysfunction (CLAD) is the leading cause of late mortality after lung transplantation. Bronchiolitis obliterans syndrome (BOS) is the obstructive phenotype of CLAD.

ISHLT/ATS/ERS clinical practice guideline.

CLAD encompasses two phenotypes: (1) BOS (obstructive, FEV1 decline, no CT findings) and (2) RAS (restrictive allograft syndrome, TLC + FEV1 decline, upper lobe fibrosis on CT). BOS staging: BOS 0 (baseline), BOS 0-p (potential), BOS 1 (FEV1 66–80%), BOS 2 (51–65%), BOS 3 (≤50%). Azithromycin, inhaled cyclosporine, and anti-reflux surgery are treatment options.

Know the BOS staging system and the two CLAD phenotypes (BOS vs RAS). BOS = obstructive decline, better prognosis. RAS = restrictive decline, worse prognosis. Azithromycin is first-line treatment for BOS (anti-inflammatory, not antibiotic effect).

Guideline — limited RCT evidence for most BOS treatments. CLAD phenotyping is evolving.