Refining the definition of BPD: Characterization of intercurrent episodes

Background: The main definitions of bronchopulmonary dysplasia (BPD), proposed by Jobe-Bancalari, Shennan et al., and Walsh et al., focus on oxygen (O2)-need and ventilatory support for the first weeks of life and at 36 weeks of post-menstrual age (PMA). Oxygen need at 36 weeks of PMA is sometimes due to intercurrent episodes (IEs) other than BPD. The aim of this retrospective study was to characterize IEs and determine their impact on BPD in preterm infants born at < 32 weeks of gestation. Methods: O2-dependence for > 28 days and at 36 weeks of PMA (±10 days) was analyzed. We classified each infant according to the three BPD definitions. Patients requiring O2 or ventilator support at 36 weeks of PMA, with no need for O2 in the first 28 days of life, were qualified for having IEs if their O2/ventilator dependence (at 36 weeks) had a limited duration and/or could be ascribed to a known condition. Then, the contribution of IEs to the BPD rate was evaluated. Results: Out of 1,210 patients, the BPD infants were 431 (35.6%), 169 (14.0%), and 186 (15.4%) according to Jobe-Bancalari, Shennan et al., and Walsh et al., respectively. Twenty-eight patients had IEs (16.6% of those on O2 at 36 weeks of PMA) indicating a mild BPD overestimation (P=0.065). Conclusion: We proposed a definition of IEs and found that IEs could lead to a potential BPD overestimation. Further research is needed to find out if patients with IE, similarly to infants with BPD, are prone to childhood complications and need preventive measures.