The median follow-up time for the patients was years (interquartile range, to years). BOS was present in 93 of 225 patients (%) at the time of the analysis. The pathologic diagnosis of OB was available in only % of patients (13 of 93 patients). All of these patients had met the spirometry criteria for BOS prior to the pathologic diagnosis. The median time to BOS development was years (interquartile range, to years). The rates of freedom from BOS at 1, 2, 3, 4, and 5 years were %, %, %, %, and %, respectively (Fig 1). BOS rates were not different by transplant era (as stratified by either pre- or post-1997 or pre- or post-1998).