County death certificate

Sudden infant death syndrome (SIDS) is a term that has been used to describe unexpected deaths of infants or young children when subsequent investigations fail to demonstrate a definite cause of death. (1,2) The concept, which was first proposed in 1969, has been controversial, and its use has been characterized by great variability in the consistency with which the requirements of standard definitions have been fulfilled. (3-5) Specifically, the term has been overused and applied to cases in which there have been obvious natural or unnatural causes of death; also, the term has been underused in favor of imprecise terms such as undetermined or unascertained. A number of other definitions that have included quite different criteria have been proposed. (6-8) The most widely used definitions have made SIDS a diagnosis of exclusion.

In 1969, at the Second International Conference on Causes of Sudden Death in Infants, it was proposed that SIDS was "the sudden death of any infant or young child which is unexpected by history, and in which a thorough postmortem examination fails to demonstrate an adequate cause of death." (1) In 1989, the National Institute of Child Health and Human Development convened an expert panel to reexamine the issue of definition. The panel proposed that SIDS was "the sudden death of an infant under one year of age, which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history." (2(p681)) This definition limited the age to <1 year and specified that a thorough examination should include examination of the death scene and review of the clinical history.

In 1992, at the SIDS International Meeting in Sydney, Australia, Bruce Beckwith proposed stratification of the definition to enable separation of cases into typical and atypical groups. (9) The proposal was not accepted at the time, although others subsequently supported subclassification. (10) In 2003, Beckwith again called for a reexamination of the definition of SIDS, with the possibility of including positive diagnostic criteria and stratification to delineate particular subsets. (11) As a result of this proposal, a meeting was held in San Diego, California, in January 2004; it was sponsored by the CJ Foundation for SIDS and involved an invited panel of experts, including pediatric pathologists, forensic pathologists, and pediatricians, all of whom had extensive experience with sudden infant death. Delegates came from Europe, North America, and Australasia.

DISCUSSION POINTS Presentations on a variety of topics were made first. Bruce Beckwith (Loma Linda University, Loma Linda, CA) discussed the history of SIDS definitions, the present status, and possible proposals for the future. He indicated that the meeting represented an attempt to formulate an approach to sudden infant death that would clarify subsets and assist research but that it was a work in progress that would need to be revisited regularly. Data presented from Seattle in the 1960s and 1970s demonstrated that 95% of SIDS cases were within the age range of 1 to 6 months. Edwin Mitchell (University of Auckland, Auckland, New Zealand) also discussed the need for redefinition and the possible place of risk factors in a new definition. He pointed out that, although specific risk factors were consistent across studies, the prevalence varied among countries; therefore, he considered it better to leave risk factors out of definitions. Mitchell emphasized the importance of researchers defining their study populations carefully. Henry Krous (Children's Hospital San Diego, San Diego, CA) presented data from the San Diego study on the frequency of risk factors and the changes that have occurred since the Back to Sleep campaigns, specifically the decrease in the winter peak and the proportionate increase in the number of cases <1 month of age. Torleiv Rognum (University of Oslo, Oslo, Norway) discussed the need for a new definition and particular problems with SIDS because of its uneasy position between the health system and the legal system. Data from Oslo in the 1980s showed an age distribution similar to the Seattle results; in later years, however, there was a decrease in the number of cases 2 to 4 months of age, with increases in the numbers of cases involving younger and older infants. When cases >360 days of age were excluded from the latter cohort, however, the distribution of cases was similar to data from Seattle before the Back to Sleep program. Randy Hanzlick (Fulton County Medical Examiner's Center, Atlanta, GA) discussed the advantages and disadvantages of reporting on the death certificate, or in other SIDS databases, those risk factors that might have been operative in causing or contributing to death, emphasizing that reporting such conditions might enable better tracking through official documentation. Hanzlick suggested that the group discuss the merits of abandoning the term SIDS and replacing it with "sudden unexplained infant death." Problems with the use and scope of the International Classification of Disease coding were reviewed, including sometimes-inadequate specificity, overlap, and variable application among coders. Roger Byard (Forensic Science Centre, Adelaide, Australia) discussed the use of the terms undetermined and unascertained in flagging cases in which significant parts of the investigation were lacking or in which there were questions regarding possible causes of death. Byard also warned against the indiscriminate use of these terms to cover inadequate autopsy and case investigations.

A group discussion followed, during which the advantages of formulating and promulgating a redefinition of SIDS were actively debated. It was agreed that creating and supporting a more inclusive SIDS definition would facilitate uniformity in diagnosis, with a resultant increase in information on current cases. It would also enable accumulated data to be better used and would provide opportunities to propose and evaluate new theories, particularly regarding possible SIDS subsets. Existing SIDS definitions were considered inadequate, often being applied too generally or too restrictively, and were exclusionary, failing to incorporate known features of the syndrome (such as sleep and age range). The conclusions of the group were based on assessments of current trends and data and were intended to be fully reevaluated in the future, when they will likely need to be modified to accommodate new developments.

The redefinition was also considered a useful step to enable more precise monitoring of changing epidemiologic patterns in sudden infant deaths and to allow more valid international comparisons. By more clearly defining subsets of sudden infant deaths, monitoring of the effects of public health recommendations and alterations in infant care practices can be facilitated. Finally, more precise definitions of subsets of sudden infant deaths, with specification of requirements for diagnosis, should help standardize investigative protocol development, by improving examinations of the circumstances of death and autopsy investigations and bringing investigations more in line with recommended guidelines. (12-14) Providing more information and more rigorous subclassification of cases should also facilitate integrated multiagency approaches to such cases. (15)

RESULTS

Definitional Approach to Sudden Infant Death

The following definition and subclassification were agreed upon.

General Definition of SIDS

SIDS is defined as the sudden unexpected death of an infant <1 year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation, including performance of a complete autopsy and review of the circumstances of death and the clinical history.

Category IA SIDS: Classic Features of SIDS Present and Completely Documented

Category IA includes infant deaths that meet the requirements of the general definition and also all of the following requirements.

Clinical

* More than 21 days and <9 months of age.

* Normal clinical history, including term pregnancy (gestational age of [greater than or equal to]37 weeks).

* Normal growth and development.

* No similar deaths among siblings, close genetic relatives (uncles, aunts, or first-degree cousins), or other infants in the custody of the same caregiver.

Circumstances of Death

* Investigation of the various scenes where incidents leading to death might have occurred and determination that they do not provide an explanation for the death.

* Found in a safe sleeping environment, with no evidence of accidental death. Autopsy