Sudden Unexplained Death in Childhood Defined

Although many sudden deaths are unexpected, deaths that remain unexplained intensify anguish among family, friends, and the community at large, especially when the decedent is an infant or child. Sudden infant death syndrome (SIDS) and sudden unexplained death in childhood (SUDC) are assigned as “causes” of death after the exclusion of any other known reason (1). There are two main differences between SIDS and SUDC: [1] SIDS is much more common, with a rate of 38.7 deaths per 100,000 live births; this compares to the SUDC rate of 1.0-1.4 deaths per 100,000 of the population; and [2] SIDS affects infants up to the age of 1 year, and SUDC affects mostly toddlers, aged greater than 1 year (highest incidence in 1-4-year-olds). Also, risk factors for SIDS (tobacco smoke exposure, placed prone for sleep, bed sharing) have not been shown to be risk factors for SUDC. These deaths deserve extensive investigation and merit dedicated research in an attempt to uncover any potential cause(s) of death in the young child. In 2005, Krous and colleagues (2) provided the working definition of SUDC: “[t]he sudden and unexpected death of a child over the age of 1 year that remains unexplained after a review of the clinical history and circumstances of death and performance of a complete autopsy with appropriate ancillary testing”. For the purposes of this chapter, discussion is limited to deaths that occurred during a sleep period.

Global Perspective

Only one-third of 55 million global deaths per year are tracked in an established civil registry (3), and only one-quarter of the global population lives in a country that registers at least 90% of births and deaths (4). Globally speaking, performance of a complete autopsy, especially when supplemented by ancillary studies, is uncommon. The United Nations (UN) and World Health Organization (WHO) are proponents of Sample Vital Registration with Verbal Autopsy (SAVVY) (5) for most countries attempting to develop a system of Vital Records. A substantial amount of information available for mortality for children aged less than 5 years is based on the collection of birth histories, verbal autopsy, disease modeling, and other strategies in absence of a civil registration system.