CHANGES IN SURVIVAL PATTERNS OF VERY-LOW-BIRTH-WEIGHT INFANTS FROM 1980 TO 1993

Objective: To determine changes in survival patterns among very low-birth-weig Methods: The records of 12 960 infants treated in nine perinatal intensive care centers in Florida were analyzed on the basis of survival (discharged alive from hospital) according to four independent variables: birth weight, race, sex, and transport status. Survival curves were generated using log linear regression techniques for each race by sex by transport status group. Results: Race, sex, and transport status correlated significantly with survival: survival percentages were higher among black infants, female infants, and infants transported to the perinatal intensive care centers than among white infants, male infants, and those admitted initially to the tertiary care centers. After 1985, 95% of neonates with birth weights between 1200 and 1500 g survived. In addition, survival of 500- to 550-g transported black male infants increased from zero to near 80% during the 13-year period; that of 500- to 550-g inborn white female infants rose from 35% to 70%. Conclusions: These results illustrate the value of taking into account race, sex, and transport status in efforts to understand the contribution that neonatal intensive care of extremely low-birth-weight infants makes to the lowering of infant mortality, and of using multivariable statistical procedures to generate predicted survival probabilities for different subpopulations. These probabilities can be applied to (1) predicting survival for specific subgroups of extremely low-birth-weight infants, and (2) helping physicians develop clinical guidelines for extending care to infants at the threshold of viability.