RATIONALE: @entity2107 is the most common morbidity of prematurity but the validity and utility of commonly used definitions have been questioned. OBJECTIVE: To compare three commonly used definitions of @entity2107 in a contemporary prospective, multicenter observational cohort of extremely preterm @entity1 . METHODS: At 36 weeks postmenstrual age, the following definitions of @entity2107 were applied to surviving @entity1 with and without imputation: need for supplemental @entity26 (Shennan definition), National Institutes of Health Workshop definition, and "physiologic" definition after a room-air challenge. MEASUREMENTS AND MAIN RESULTS: Of 765 survivors assessed at 36 weeks, @entity2107 was diagnosed in 40.8%, 58.6% and 32.0% @entity1 , respectively, with the Shennan, workshop and physiologic definitions. The number of unclassified @entity1 was lowest with the workshop definition (2.1%) and highest with the physiologic definition (16.1%). After assigning @entity1 discharged home in room-air before 36 weeks as no @entity2107 , the modified Shennan definition compared favorably to the workshop definition with 2.9% unclassified @entity1 . Newer management strategies with nasal cannula flows up to 4 liters/minute or more and 0.21 fraction of inspired @entity26 at 36 weeks obscured classification of @entity2107 status in 12.4% of @entity1 . CONCLUSIONS: Existing definitions of @entity2107 differ with respect to ease of data collection and number of unclassifiable cases. Contemporary changes in management of @entity1 such as use of high-flow nasal cannula limit application of existing definitions and may result in misclassification. A contemporary definition of @entity2107 that correlates with @entity1576 in childhood is needed. Clinical trial registered with ClinicalTrials.gov (NCT01435187).

Comparisons and Limitations of Current Definitions of XXXX for the Prematurity and Respiratory Outcomes Program.

@entity1 :: ('9606', 'Species') :: ['infants'] @entity2107 :: ('MESH:D001997', 'Disease') :: ['Bronchopulmonary dysplasia', 'bronchopulmonary dysplasia'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity1576 :: ('MESH:D012131', 'Disease') :: ['respiratory morbidity']
@entity2107 :: (MESH:D001997,Disease) :: ['Bronchopulmonary Dysplasia']
