Bronchiolitis Obliterans Syndrome and Restrictive Allograft Syndrome: Do Specific Risk Factors Differ?

Purpose Chronic rejection is one of the major problems hampering long-term survival after lung transplantation (LTx). Recently, it became clear that patients with an irreversible decline in FEV1 can either develop an obstructive (Bronchiolitis Obliterans Syndrome, BOS) or a restrictive lung function defect (Restrictive allograft syndrome, RAS). Our aim was to investigate whether risk factors for BOS and RAS may be different. Methods and Materials A retrospective review of our patient cohort (LTx between 01/01/2001 and 01/11/2011) with a survival >90 days post LTx was performed (n=380). Patients with an irreversible decline in FEV1, not responding to azithromycin, and without another explanation were identified. BOS was diagnosed according to ISHLT criteria, RAS was diagnosed using TLC or FEV1/FVC ratio, combined with CAT-scan findings. Acute rejection (AR) and lymphocytic bronchiolitis (LB) were defined according to ISHLT criteria. Infections were defined as hospitalizations needing treatment with antibiotics. Colonization with Pseudomonas aeruginosa was defined as a positive culture of Pseudomonas in BAL fluid/sputum without need for treatment. Results 277 patients never experienced a persistent decline in FEV1 (stable, 69.8%). Within the remaining 103 patients, 24 developed RAS (23.3%) and 79 BOS (76.7%). Patients with RAS were significantly younger compared to BOS and stable patients (p Conclusions AR, LB, colonization with Pseudomonas, and infection are major risk factors for the later development of BOS and RAS. The exact mechanisms, remain to be established.