Population-based study of chronic lung disease in very low birth weight infants in North Carolina in 1994 with comparisons with 1984

Objective. To assess the pulmonary outcomes of very low birth weight (VLBW) infants in North Carolina in 1991 and to compare rates of survival and chr onic lung disease (CLD) between 1994 and 1984 (see reference 2). Methods. Data were collected prospectively by collaborators from all 13 neo natal intensive care units in North Carolina to determine survival and pulm onary 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 de fined as oxygen or ventilator therapy at 36 weeks' postmenstrual age (PMA). For comparisons with the 1984 cohort, survival and pulmonary outcomes of i nfants 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 li ve births. Of VLBW infants, 224 (15%) died before 48 hours of age. The over all rate of CLD in 1994 at 36 weeks' PMA was 25%. Rates by birth weight gro up were 57% for 500 to 750 g birth weight (BW), 41% for 751 to 1000 g BW, 1 9% for 1001 to 1250 g BW, and 8% for 1251 to 1500 g BW. Infants who receive d ventilator therapy for >48 hours accounted for 89% of the CLD cases. The CLD rate tit 36 weeks' PMA. in infants weighing 751 to 1500 g was 37% for t hose 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, t he CLD rates in those infants defined to be at risk were significantly high er in 1994 at 30 days (68% vs 54%) and at 3 months (24% vs 15%) of postnata l age. For at-risk infants in 1994, there were fewer infants on the ventila tor, but more infants oil oxygen alone at all measured time points compared with 1984. Conclusion. Survival of VLBW infants has improved since 1984. Ventilator th erapy for >48 hours remains a significant risk factor for CLD. The incidenc e of CLD has increased from 1984 to 1994 but has shifted from ventilator to oxygen therapy.