Downes Score as a Predictor of Nasal Continuous Positive Airway Pressure Failure in Neonates of 28 - 36 Weeks Gestation with Respiratory Distress: A Survival Analysis

Background: Respiratory distress is the most often encountered problem in preterm infants and the most frequently encountered reason for neonatal intensive care unit (NICU) admission. It can develop into respiratory failure and cause high morbidity and mortality. Noninvasive respiratory support, such as nasal continuous positive airway pressure (NCPAP), was the first line for neonates with respiratory distress. The progression of respiratory distress to respiratory failure in neonates with NCPAP (NCPAP failure) increases the need for mechanical ventilation on the first day of life. With limited resources, clinical observation is critical to predict prognosis and golden time for referral. Downes scores are the accurate and easiest measurement that is used to determine the severity and monitoring of respiratory distress in neonates. However, in Indonesia, there has still been no study that showed an effect of the increment of Downes score in 24 hours and the risk of NCPAP failure. Objectives: This study aimed to measure the association of Downes score at birth, ages 2, 6, 12, and 24 hours, and the risk of NCPAP failure in the first 72 hours using survival analysis. Methods: This prospective observational cohort study included all neonates with 28 - 36 weeks gestation born at Hasan Sadikin General Hospital, Bandung, Indonesia, within March to May 2019, with respiratory distress and NCPAP as respiratory support. Clinical monitoring was conducted using Downes score at birth, 2, 6, 12, and 24 hours of age. The time of NCPAP failure in the first 72 hours was also obtained. Survival analysis with Kaplan-Meier and Cox regression was used to determine the association. Results: This study analyzed 121 neonates at 72 hours with an overall survival rate of 70.2% and a mean survival time of 61.1 hours. Neonates born 28 < 32 weeks and birth weight 1000 - 1499 g had the lowest survival (54.5% and 56.9%). Downes score ≥ 4 at birth and 2 and 6 hours had lower survival than Downes score < 4 (67.7%, 60.5%, and 52.7%). The risk of NCPAP failure in 72 hours was increased with a higher Downes score at 2 hours (hazard ratio [HR] = 1.86 [95% confidence interval [CI]: 1.3 - 2.6, P < 0.001), 6 hours (HR = 1.67 [95% CI: 1.2 - 2.2], P < 0.001). Downes score ≥ 4 at 2 hours (3.26 times, P = 0.030) and 6 hours (2.44 times, P = 0.014) had a high risk of NCPAP failure in 72 hours. Conclusions: The increase in Downes score was associated with a high risk of NCPAP failure at 72 hours of age in preterm neonates with respiratory distress. Two to six hours of monitoring of the Downes score should be considered a critical time for referral.