Preemies Much Safe at Big Hospitals - Study

A new study has found that very-low-birth-weight infants are more likely to survive if born in hospitals having high performing Neonatal Intensive Care Units (NICUs).

Mortality among very-low-birth-weight infants has been found to be lowest for deliveries that occurred in hospitals with Neonatal Intensive Care Units (NICUs) having both a high level of care and a high volume of such patients. Thus, the increased use of these facilities might reduce mortality among very-low-birth-weight infants.

A research was conducted by Ciaran S. Phibbs, Ph. D., of Stanford, and his team. They examined differences in neonatal mortality among infants with very low birth weight (below 1500 g) among NICUs with various levels of care and different volumes of very-low-birth-weight infants.

According to the report in New England Journal of Medicine (Issue dated May 24), if born in a hospital having NICUs offering high level of care and high patient volume, an estimated 21% of infants weighing less than 1500 g might have lived.

In 2000, less than 25% of these high risk infants were born in hospitals having high care and high volume NICUs, and this percentage is on decline. This can be attributed to low or moderate volume NICUs in most hospitals in California in 1990s.

To study these differences in neonatal mortality among various NICUs in California Hospitals, they linked birth certificates, hospital discharge abstracts (including inter- hospital transfers), and fetal and infant death certificates to assess neonatal mortality rates among 48,237 very-low-birth-weight infants who were born in California hospitals between 1991 and 2000.

Mortality rates among very-low-birth-weight infants varied according to both the volume of patients and the level of care at the delivery hospital. Levels of care, for example, included provision of mechanical ventilation or neonatal surgery (open heart, cardiopulmonary bypass, or extracorporeal membrane oxygenation). The effect of volume also varied according to the volume of care.

When very low birth weight deliveries occurred in hospitals with tertiary level NICUs (treating more than 100 infants annually), mortality was reported to be the lowest. In 1991, only 35.6% of these infants were born in such facilities while 21.5 % in 2000.

As compared with a high level of care and a high volume of very-low-birth-weight infants (more than 100 per year), lower levels of care and lower volumes (except for those of two small groups of hospitals) were associated with significantly higher odds ratios for death, ranging from 1.19 (95% confidence interval [CI], 1.04 to 1.37) to 2.72 (95% CI, 2.37 to 3.12).

According to the research, a NICU that treats 50 very-low birth-weight infants a year corresponds to an average census of about 15 patients. Thus, hospitals having small to moderate size NICUs account for most of the increase in the risk of death.

Although the study focused on many potential confounder's, data was limited to information from birth certificates and discharge abstracts. Secondly, the only outcome assessed was mortality, yet other outcomes, such as intraventricular hemorrhage and chronic lung disease are also important, the researchers reported.