Effectiveness of antenatal dexamethasone in reducing respiratory distress syndrome and mortality in preterm neonates: a nested case control study

Abstract

Background: Respiratory distress syndrome (RDS) is a significant cause of preterm neonatal morbidity and mortality globally. Measures like the use of antenatal corticosteroids (ACS) and immediate resuscitation of the newborn after birth are taken to abate preterm related complications. Most studies that evidenced the benefit of ACS were done in high resource settings. However, some studies in low resource settings reported no benefit of ACS in improving neonatal outcomes. Such findings warrant for further studies in different settings. Aim: To assess the effectiveness of antenatal dexamethasone in reducing RDS and mortality in preterm neonates in Dar es Salaam, Tanzania. Methods: A three-month nested case-control study was conducted in Dar es Salaam at Muhimbili National Hospital and Amana Regional Referral Hospital. A total of 330 neonates delivered at 28 to 34 gestational weeks were enrolled consecutively and followed up through the study period. RDS was diagnosed within 48 h after birth. Cases were neonates with RDS and controls were those without. Maternal and neonatal socio-demographic and clinical data were recorded using a data abstraction forms. Proportions were used to summarize descriptive statistics. Overall mortality rate was calculated using incidence rate. Log ranking test and cox regression were used to graphically compare probability of death with time and measure association, respectively. Continuous variables were summarized using median and range then analyzed by Mann-Whitney U test. All tests were considered statistically significant at p <0.05. Results: Out of 330 preterm neonates enrolled, of which 110 were cases and 220 were controls. 71.8% of the participants were from MNH and 28.2% from Amana regional referral hospital. The median gestational age at delivery was 30 weeks and 6 days (28-34) among cases and 33 weeks (28-34) among controls (p<0.001). A one-minute APGAR score of less than seven was assigned to 38.2% of cases compared to 14.5% of controls (p<0.001). ACS exposure was not associated with RDS occurrence (OR: 0.81; 95% CI 0.69-0.94), one minute APGAR score of less than 7 (OR: 3.11; 95% CI 1.54-6.30), and neonatal birth weight (OR: 0.998; 95% CI 0.997-0.999) were significantly associated with RDS. The overall mortality rate was 9 per 1000 neonates. Neonatal mortality occurred only among cases. A unit increase in gestational age was associated with a 30% reduction in neonatal mortality (Adjusted hazard ratio, AHR: 0.70, 95% CI: 0.5-0.92, p=0.011). Conclusion: Antenatal dexamethasone is not associated with reduced RDS occurrence and neonatal mortality rates. Increase in gestational age is found to be an independent protective factor against RDS and neonatal mortality. One-minute APGAR score of < 7 and low neonatal birth weights are independent predictors of RDS in preterm neonates