Annex C: Causes of Neonatal Mortality: Comparison of Numbers from the Global Burden of Disease with Those from the Child Health Epidemiology Reference Group
This chapter has examined the consequences of incorporating stillbirths and neonatal deaths (deaths in the 28 days following live birth) into the Global Burden of Disease (GBD) framework. Methods and results of the GBD are presented elsewhere in this book and, in particular, chapter 3 discusses the estimates of deaths by age and cause for 2001 that form the basis for results throughout this book and in this chapter. Estimates of deaths from specific causes undergo continual revision as new data and syntheses become available, yet establishing a time cutoff is a necessary (if somewhat arbitrary) condition for preparing a volume with consistent estimates across chapters. For this volume, the cutoff date for the estimates of deaths by cause in 2001 was late 2003. That date was itself established in response to the need for a separate book—Jamison and others (2006)—to have a consistent set of demographic and epidemiological numbers feeding into its highly diverse chapters.
During 2001, the World Health Organization (WHO) established the Child Health Epidemiology Reference Group (CHERG) to undertake a new synthesis of data on causes of death among children under five. While some early CHERG results influenced the GBD numbers in this volume, for the most part, CHERG's work became available well after the cutoff date for this iteration of the GBD. For this reason, the 2005 WHO estimates (Bryce and others 2005; WHO 2005b) of causes of death among children under five based on CHERG (CHERG/WHO) differ to some extent from the GBD ones used in this volume. Chapter 5 further discusses the two sets of estimates for under-five deaths, and the importance of envelope and epidemiological consistency constraints in generating the GBD numbers. In terms of data sources, the GBD uses epidemiological data together with vital registration data (where available), models extrapolating from vital registration data, and epidemiological consistency checks. CHERG relies relatively more on verbal autopsy based epidemiological data for causes of child death.
The work of CHERG, however, provides a critical input to this chapter not available from the GBD work, that is, a breakdown of the causes of death specifically for the neonatal period. One of the motivations of this chapter is that neonatal deaths account for fully 37 percent of the worldwide total of deaths among children under age five. In preparing this chapter, therefore, we needed to draw fully on the CHERG analyses of neonatal deaths while—to ensure consistency and comparability with numbers elsewhere in this volume—we use the GBD estimates of total deaths among children under five. This allows estimates of the neonatal burden to be inserted into the larger context of the GBD with its inclusion of 136 causes as well as all age groups older than age five. The specific assumptions we made to reconcile GBD and CHERG numbers are made clear in the text with table 6.4 and in the notes to table 6.4.
The CHERG/WHO results appear as percentages of deaths by one set of causes for neonates and by a mostly different set of causes for children ages 28 days to 5 years. This makes direct comparison with the GBD numbers difficult in the formats in which the two sets of numbers are presented. The difficulty is compounded by occasional differences in the labels (and content) of cause categories and by the fact that the GBD deals with far more causes than CHERG/WHO. Even the truncated GBD cause list used in this chapter uses 35 instead of 136 causes, in contrast to the 10 used by CHERG/WHO. To facilitate comparison of the two sets of findings, annex table 6C.1 uses the 6 of the 10 CHERG/WHO cause categories that are relevant to neonates to compare this chapter's and CHERG's findings for neonatal deaths. To construct table 6C.1 we took proportional allocations of deaths from CHERG/WHO presented in figure 2 of Bryce and others (2005) and applied those proportions to the estimated number of neonatal deaths (3.896 million) used in this chapter. The table is for the world as a whole.
[Table .]
