175 EARLY PEAK RESPIRATORY SEVERITY SCORE AS A RISK FACTOR FOR BRONCHOPULMONARY DYSPLASIA. (1st January 2005) - Lorch, S. A.
Abstract : Background: Bronchopulmonary dysplasia (BPD) is a major complication of prematurity, but the ability to predict which infants with a given birth weight or gestational age will experience this morbidity remains poor. We consider whether a physiologic marker of respiratory status between 4 and 10 days after birth, the PRSS (mean airway pressure × FiO2 ), can also serve as an early predictor of BPD. Methods: We studied infants <32 weeks gestational age requiring CPAP or ventilation who were enrolled in two multicenter trials, the NO CLD trial (infants randomized to either postnatal nitric oxide or placebo at 20 centers) and the North American Thyrotropin-Releasing Hormone study (TRH) (Ballard RA, NEJM, 1998). Peak respiratory severity score (PRSS) was collected from bedside flowsheet data. Logistic regression models were developed to determine the association of the PRSS between 4 and 10 days after birth and the development of BPD, defined as an oxygen requirement at 36 weeks postmenstrual age. Birth weight and gestational age were included in separate models to control for baseline risk of BPD. Results: 332 patients from the NO CLD trial and 194 from the TRH trial required CPAP or mechanical ventilation between days 4 and 10 after birth. The mean birth weight was 748 6 124 g and gestational age was 25 6 2.5 weeks. 308 (59%) developed BPD. Logistic regression models including birth weight and PRSS showed that the PRSS between 4 and 10 days was significantly associated with BPD using thresholds of both 3.5 [OR 2.0, 95% CI 1.4-2.8] and 4.0 [OR 2.1, 95% CI 1.5-3.0]. Although birth weight alone was significantly associated with BPD (p=0.03), when PRSS was added to the model, birth weight was no longer significant. When gestational age was substituted for birth weight in the predictive models, PRSS remained significantly associated with the development of BPD. Both PRSS thresholds remained significantly associated with BPD when each trial was analyzed separately. Conclusions: The PRSS that a ventilated infant reaches between 4 and 10 days after birth is a significant risk factor for occurrence of BPD. This finding emphasizes the role of early postnatal lung disease in the development of BPD. PRSS may be a useful clinical and research tool to identify infants at increased risk for BPD.