Identification of neonatal deaths in a large managed care organisation

The neonatal (< 28 days) mortality rate (NMR) is one of the most commonly employed maternal and child health epidemiological measures. It is also being employed in quality measures ("report cards') used to assess the performance of health care organisations. The objectives were to (1) develop methods for the rapid quantification of the neonatal mortality rate in a multi-hospital system, the Kaiser Permanente Medical Care Program's Northern California Region (KPMCP NCR), (2) develop methods for generating facility-specific rates and case lists, and (3) ascertain the capture rates of the information sources available to us. Potential neonatal deaths were identified in the KPMCP NCR for the 1990 and 1991 calendar years from 3 sources: (1) clerical searches of local facility records, (2) electronic searches of the KPMCP NCR hospitalisation database, and (3) linking KPMCP electronic birth records to death certificate tapes. The medical records of all infants identified through these methods were reviewed. The neonatal mortality rate was calculated in three ways: (1) including all livebirths, (2) excluding births weighing < 500 g, and (3) adjusting for prematurity by increasing the follow-up period in preterm babies (these babies were included as neonatal deaths if they died up to 40 weeks corrected age + 27.9 days). A total of 352 records out of 64 469 birth records in the KPMCP NCR were reviewed. If one includes babies < 500 g, the neonatal mortality rate was 3.72/1000 livebirths; if these babies are excluded, the rate was 3.05/1000. Adjusting for prematurity increased these rates to 3.91/1000 and 3.24/1000, respectively. Accurate quantification of the neonatal mortality rate in a multi-hospital system requires the use of multiple information sources. Use of a single source can lead to varying rates of over- or under-estimation. It is possible to employ our methodology for both research and operational purposes.