Population-based Study of Chronic Lung Disease in Very Low Birth Weight Infants in North Carolina in 1994 With Comparisons With 1984

Abstract

Objective. To assess the pulmonary outcomes of very low birth weight (VLBW) infants in North Carolina in 1994 and to compare rates of survival and chronic lung disease (CLD) between 1994 and 1984 (see reference 2). Methods. Data were collected prospectively by collaborators from all 13 neonatal intensive care units in North Carolina to determine survival and pulmonary outcomes of infants with birth weights of 500 to 1500 g. State vital statistics data were used to confirm completeness of the sample. CLD was defined as oxygen or ventilator therapy at 36 weeks' postmenstrual age (PMA). For comparisons with the 1984 cohort, survival and pulmonary outcomes of infants defined to be at risk for CLD (ventilated >48 hours and survived 30 days) were recorded at 30 days, 3 months, and 6 months of postnatal age. Results. Outcome data were available for 1413 (92%) of the in-state VLBW live births. Of VLBW infants, 224 (15%) died before 48 hours of age. The overall rate of CLD in 1994 at 36 weeks' PMA was 25%. Rates by birth weight group were 57% for 500 to 750 g birth weight (BW), 41% for 751 to 1000 g BW, 19% for 1001 to 1250 g BW, and 8% for 1251 to 1500 g BW. Infants who received ventilator therapy for >48 hours accounted for 89% of the CLD cases. The CLD rate at 36 weeks' PMA in infants weighing 751 to 1500 g was 37% for those ventilated >48 hours versus 5% for those ventilated <48 hours (OR: 7.1; 95% CI: 4.4–11.3). Overall survival in 1994 was significantly higher for infants than in 1984 (78% vs 74%), most notably in infants 500 to 750 g BW (37% vs 24%), and 751 to 1000 g BW (82% vs 65%). When compared with 1984, the CLD rates in those infants defined to be at risk were significantly higher in 1994 at 30 days (68% vs 54%) and at 3 months (24% vs 15%) of postnatal age. For at-risk infants in 1994, there were fewer infants on the ventilator, but more infants on oxygen alone at all measured time points compared with 1984. Conclusion. Survival of VLBW infants has improved since 1984. Ventilator therapy for >48 hours remains a significant risk factor for CLD. The incidence of CLD has increased from 1984 to 1994 but has shifted from ventilator to oxygen therapy. bronchopulmonary dysplasia, epidemiology, infant, low birth weight, intensive care units, neonatal statistics, infant mortality, prospective studies.