Gestational Age Should Not Be Sole Determinant for Treatment
Among the difficult decisions that parents and physicians make, whether to initiate or forgo intensive care for extremely premature infants ranks among the highest. Physicians traditionally base such decisions on gestational age: intensive care is provided routinely at 25 weeks, physicians discuss options with parents when neonates are aged 23 to 24 weeks, and at 22 weeks, comfort care is offered. A new study in The New England Journal of Medicine, however, indicates that outcomes for infants who undergo ventilation are better predicted by five factors (including gestational age) than by gestational age alone (358;16:1672-1681).
UAB neonatologist Wally A. Carlo, MD, participated in the multicenter study that assessed prenatal and perinatal risk factors that affect survival and impairment of neurodevelopment for newborns aged 22 to 25 weeks. Researchers studied a cohort of 4446 infants in the Neonatal Research Network of the National Institute of Child Health and Human Development. Of those newborns, 83% received mechanical ventilation. Using standardized measures of mental development, vision, and hearing, investigators assessed the health status of 4192 surviving infants at corrected ages of 18 to 22 months. Forty-nine percent died, 61% died or had profound impairments, and 73% died or had some impairment.
Investigators found that weighing additional factors along with gestational age gives a better estimate of the likelihood of a favorable outcome with intensive care than gestational age alone. “Estimates of probability of adverse outcomes with intensive care vary widely among infants at the same gestational age. Every assessment of gestational age has an error of up to 1 to 2 weeks,” Carlo says, “and 1 or 2 weeks makes a big difference in outcomes for extremely premature babies.”
Female sex, antenatal steroid use, singleton birth, increased birth weight (per 100 g increment), and higher gestational age were associated with reduced risk of death and reduced risk of profound neurodevelopmental impairment or any neurodevelopment impairment—each factor conferring an advantage similar to a 1-week increase in gestational age.
“Steroids alone increase survival by 5% to 15%,” he says. Study authors acknowledge the high total resource use per survivor, concluding that “extending intensive care to all of the most immature infants would entail considerable suffering, resource use, and cost” to benefit a small number of infants.
Previous studies, including some by Carlo and UAB neonatologist Namasivayam Ambalavanan, MD, indicate that consideration of birth weight, antenatal steroid use, race, sex, and other factors, along with gestational age, improve accuracy and prognostic precision (J Pediatr. 2007;151[5]:500-505; 2006;148[4]:438-444).
The provider’s experience and the medical center’s level of care are important in survival and neurodevelopmental impairment. A recent study found that mortality for very-low-birth-weight infants (≤1500 g) is lower in high-level, high-volume neonatal intensive care units (NICU) (N Engl J Med. 2007;356[21]:2165-2175). UAB’s level 3D NICU provides the highest level of care, from mechanical ventilation to cardiac surgery. “Our care consistently ranks among the best in the nation,” Carlo says.
For more information contact Dr. Wally Carlo or Dr. Namasivayan Ambalavanan at 1-800-UAB-MIST or at mist@uabmc.edu.