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Chronic oxygen dependency in infants born at less than 32 weeks' gestation: incidence and risk factors.

OBJECTIVE
To assess incidence and clinical risk factors of chronic oxygen dependency (COD) among survivors who were born at or before 31 weeks' gestation.


METHODS
This prospective, multicenter study enrolled 802 infants who were born at or before 31 weeks' gestation and admitted to 8 level III neonatal intensive care units in northern and eastern France from January 1 through December 31, 1997. Need for oxygen to maintain oxygen saturation between 92% and 96% was assessed at 28 days of life and at 36 and 42 weeks' postconceptional age (PCA). Stepwise logistic regression analysis was used to identify the incidence of COD and the risk factors related to its occurrence.


RESULTS
The mortality rate was 14%. Antenatal corticotherapy was administered to 51% of patients, surfactant therapy to 76% of the ventilated patients, and high-frequency oscillatory ventilation at day 1 to 32%. At 28 days and 36 and 42 weeks' PCA, respectively, 25%, 15%, and 6% of survivors had COD. After adjustment for intercenter variations, we identified the significant risk factors for COD at these dates: a low gestational age, a high score on the Clinical Risk Index for Infants, intrauterine growth restriction, and surfactant treatment.


CONCLUSION
COD incidence was high at 28 days of life but decreased dramatically by 42 weeks' PCA. This study confirmed previously reported risk factors and underlined the importance of intrauterine growth restriction and the Clinical Risk Index for Infants as significant risk factors.