A Retrospective Chart Review Study of Patients With Chronic Lung Allograft Dysfunction-Bronchiolitis Obliterans Syndrome (CLAD-BOS) Post Lung Transplantation

Inclusion Criteria: 1. Adult patients ≥ 18 years of age on the date of CLAD-BOS diagnosis 2. Patients with a CLAD-BOS clinician diagnosis from as early as 01 January 2013 3. Patients with CLAD-BOS clinician diagnosis made at least 12 months after lung transplant 4. Patients received at least basic maintenance regimen of immunosuppressive agents including tacrolimus, a second agent such as but not limited to mycophenolate mofetil or azathioprine (or other anti-proliferative agent), and a systemic corticosteroid such as prednisone as third agent for at least 1 month before the index date. As long as the basic maintenance regimen is maintained for the abovementioned period, patients will still be considered eligible for the study even if they are receiving other immunosuppressive agents in addition to the basic maintenance regimen. Exclusion Criteria: 1. Patients with severe concomitant disease at the time of index date, which according to physician's judgment, can interfere with CLAD-BOS progression and mortality (e.g., malignancies, severe chronic diseases) 2. Patients who have been exposed to any investigational medical products in the 4 weeks prior to index date or during the post-diagnosis period 3. Patients with confirmed other CLAD phenotype (e.g., restrictive allograft syndrome) according to physician's judgment.