Abstract 1516
Neonatal Epidemiology and Follow-up Poster Symposium, Monday, 5/3
Objective: To explore the hypothesis that variation in respiratory management among Newborn Intensive Care Units (NICUs) explain differences in chronic lung disease (CLD) rates among surviving very low birthweight (VLBW) infants. Design: Case-cohort study. Setting: NICUs at one medical center in New York (Babies' and Children's Hospital) and two in Boston (Beth Israel Hospital and Brigham and Women's Hospital). Study Population: 452 infants born at 500 to 1500 grams birth weight between January 1991 and December 1993 who were enrolled in an epidemiologic study of neonatal intracranial white matter disorders. Case Definition: Supplemental oxygen required at 36 weeks post-menstrual age. Results: The prevalence rates of CLD differed substantially between the centers: 4% at Babies' and 22% at the two Boston hospitals, despite similar mortality rates. Initial respiratory management at Boston was more likely than at Babies' to include mechanical ventilation (75% vs. 29%) and surfactant treatment (45% vs. 10%). Case and control infants at Babies were more likely than those at Boston to have higher PaCO2 and lower pH values on arterial blood gases. However, after adjusting for baseline risk factors in multivariate logistic regression analyses, most ventilator settings and measures of oxygenation were not associated with CLD. In time-oriented logistic regression analyses, among ventilated infants, CLD risk was elevated for maximum PIP>25 and maximum F1O2=1.0 on the day of birth, lowest PIP>20 and maximum PaCO2>50 on postnatal days 1-3, and lowest white blood cell count <8K on postnatal days 4-7. Even after adjusting for these variables, VLBW infants in Boston continued to be at increased risk of CLD when compared with similar infants at Babies' Hospital. Conclusion: In multivariate analyses adjusted for baseline risk, a number of specific measures of respiratory care practice during the first postnatal week were associated with the risk of a VLBW infant developing CLD. However, much of the increased risk of CLD among VLBW infants hospitalized at two Boston NICUs, compared with those at Babies' Hospital, was explained by the more frequent decision by Boston physicians to use mechanical ventilation.
