A Retrospective Chart Review Study of Patients With CLAD-BOS Post Lung Transplantation

This was a retrospective, multinational, multicenter, observational chart review study conducted in adult patients with clinically diagnosed chronic lung allograft dysfunction-bronchiolitis obliterans syndrome (CLAD-BOS) following lung transplantation. All data were retrospectively collected from existing patient medical records; no interventions were applied as part of the study, and no protocol-mandated patient assessments or follow-up visits were required. The observational period for each patient encompassed multiple time points relevant to the development and progression of CLAD-BOS. Patients were identified within a CLAD-BOS diagnosis window spanning from 01 January 2013 through the most recent data available at the participating study sites. The index date was defined as the date of clinician diagnosis of CLAD-BOS as documented in the medical record. Spirometry parameters at diagnosis were based on the spirometry assessment closest to the diagnosis date. Personal best FEV1 was defined as the highest post-transplant FEV1 value documented prior to the diagnosis of CLAD-BOS, based on available spirometry measurements collected after lung transplantation and before diagnosis. The personal best FEV1 date corresponded to the time point at which this best post-transplant FEV1 value was identified. The personal best post-transplant FEV1 value was defined as the mean of the 2 best post-transplant FEV1 measurements taken at least 3 weeks apart, with the date being that of the first value. CLAD-BOS onset (≤ 80% vs best-FEV1) was defined based on a sustained decline in FEV1 relative to the post-transplant best value, as documented in clinical records, with the onset date corresponding to the first occurrence of a decline meeting this criterion and confirmed by a subsequent measurement occurring at least 3 months apart. For each patient, the onset date will be programmatically derived from the data collected starting from the lung transplant date. For other spirometric parameters, including forced vital capacity (FVC), FEV1/FVC ratio, and forced mid-expiratory flow (FEF25-75%), best post-transplant and onset values were derived from the same spirometry assessments in which the corresponding FEV1 best and onset values were measured. The pre-diagnosis period extended from lung transplantation up to, but not including, the index date. The post-diagnosis period extended from, and included, the index date through the last available follow-up or death. The observation period ended at the earliest occurrence of death or the last date on which the patient was known to be alive based on available medical record documentation.