Cases Of Unexpected Infant Death Research Articles

Bed Sharing Deaths In Infancy - Sids or Asphyxia?

To the Editor: The paper by Yoo et al. (1) draws attention to the significant numbers of unexpected infant deaths that are occurring in shared sleeping situations. It is now well-recognized that the more comprehensively cases of unexpected infant death are investigated, the greater is the number of cases where deaths are attributed to something other than sudden infant death syndrome (SIDS) (2, 3). However, although bed sharing deaths are still often universally attributed to SIDS (1, 4), the possibility of an asphyxial mechanism of death in some cases must be recognised (5, 6). In support of this, a recent study in South Australia demonstrated that the male to female ratio in infants who died alone was approximately 2:1, as is typical of SIDS deaths. This was significantly different to the sex ratio of infants who died in shared sleeping situation which approached unity (7). One explanation for this marked difference is that although females are less vulnerable to SIDS than males, this protection does not extend to situations where lethal asphyxia may occur; i.e. gender does not protect an infant from accidental suffocation, or so-called 'overlaying'. A more detailed description of the nature of shared sleeping arrangements in Korea from the authors would be a useful addition to their data, in addition to a comparison of the sex ratio of the alone and shared sleepers, to see if the usual SIDS male to female ratio is present, or not, in this population.

Changing infant death rates: diagnostic shift, success story, or both?

Over the past 20 years there have been remarkable and gratifying falls in the rates of infant deaths in many Western countries due to declining numbers of cases attributed to sudden infant death syndrome (SIDS). This reduction in unexpected infant fatalities has been due in large part to the effects of the ‘‘Reduce the Risks’’ campaigns where community awareness programs were undertaken by local and national SIDS organizations to warn parents and carers of the potential dangers of prone sleeping, cigarette smoke exposure, head covering and overheating [1]. However, in the late 1970s changes in infant mortality had also been noted in a number of jurisdictions which were not due to a real reduction in lethal events, but were due instead to pathologists reassigning causes of death—in this instance from respiratory infections to SIDS [2]. This was termed a diagnostic shift and was clearly identified by a lack of change in overall infant mortality figures. Diagnostic shift was regarded as an unfortunate event which had the potential to influence the recording of mortality figures. Concerns were expressed that the fall in infant death rates in the early 1990s might be due to a similar diagnostic shift distorting mortality data [3, 4]. In this instance, however, studies revealed that the fall in numbers of SIDS deaths was matched by an associated fall in overall infant mortality, and that other causes of infant death had not significantly increased [4]. Thus, changing diagnostic practice by pathologists was not thought to be a factor in the initial change in patterns of infant death. In addition to identifying risk factors for SIDS, the 1990s was also characterized by moves to improve infant death investigations with the establishment of standardized protocols for both death scene and autopsy examinations [5, 6]. These protocols were aimed at improving diagnostic accuracy by providing additional information to enable more accurate determination of causes of death and to facilitate more meaningful comparisons of infant death rates between populations. In addition it was hoped that international guidelines would improve research in this area and further reduce infant death rates. The International Standardized Autopsy Protocol (ISAP) and Sudden Unexplained Infant Death Investigation Report Form (SUIDIRF) were subsequently formulated, endorsed by professional bodies, and published [5, 6]. Trends in infant deaths and diagnostic practices continued to be monitored throughout the 1990s and this subsequently showed that changes in diagnoses were occurring; i.e. the concerns that a diagnostic shift was present were realized. Pathologists had been identifying more cases of accidental asphyxia from dangerous sleeping environments [7, 8], in addition to detecting rarer forms of sudden death involving underlying metabolic and genetic conditions [9]. Although this was initially considered to be a problem, representing again a possible arbitrary reclassification of deaths, it was soon realized that this was in fact a positive finding. Changes in diagnoses in this instance endorsed the usefulness of protocols by demonstrating that they were providing useful information to help pathologists to identify conditions that would previously have been included under the umbrella of ‘‘SIDS.’’ In other words, protocols were allowing more cases of unexpected infant death to be removed from the ‘‘diagnostic dustbin’’ of SIDS [10]. As is often the case, however, improvements in medicine are often accompanied by opposing trends. In this case R. W. Byard (&) Discipline of Anatomy and Pathology, Level 3 Medical School North Building, The University of Adelaide, Frome Road, Adelaide 5005, Australia e-mail: roger.byard@sa.gov.au

Sudden unexpected death in infancy (SUDI): suggested classification and applications to facilitate research activity

SUDI, or sudden unexpected death in infancy, is a term that has been variably used to refer to all cases of sudden and unexpected deaths in infancy, and not just to those where the death has been attributed to sudden infant death syndrome or SIDS [1]. A variety of reasons have motivated the development of this terminology that have involved the concerns of families, pathologists and researchers. For example, there has been a trend among pathologists recently to use terms such as ‘undetermined’ or ‘unascertained’, rather than SIDS, to reflect the lack of diagnostic features in certain cases. These terms are also used when the findings are not typical of SIDS, but where no definite conclusion can be reached. The terms indicate that no specific diagnosis has been, or can be, made. Unfortunately such terminology may have quite a damaging impact upon families with statements made that the terms are perceived as ‘stigmatizing’ as they imply that ‘‘there is just not enough evidence to prosecute’’. A more general term such as SUDI might avoid this type of negative effect [2, 3]. As for pathologists, the concept of SUDI means that all unexpected infant deaths will be included under this umbrella so that, for example, the death of an infant in a shared sleeping situation with an adult, that may have been classified as SIDS, overlaying, or undetermined, by different pathologists, would still fall under the umbrella of SUDI. This means that a case can be flagged as a SUDI with sub-classifications based on possible mechanisms of death. In cases where there are definite findings such as blunt trauma from a vehicle crash or asphyxia from hanging, the cause of death will be obvious even though the cases still fall under the definition of SUDI. Use of the term SUDI will also be of benefit to researchers, as all cases of unexpected infant death will be registered, and so will be available for study without the potential problem of differences in pathological diagnoses resulting in similar cases being classified differently. Certainly a problem that has occurred many times in the field of sudden infant death is the variable and inconsistent use of terminology. The term SIDS has been idiosyncratically applied and misused despite clear definitions being promulgated [4–6]. Similarly there has been quite conflicting and erratic use of the term SUDI and attempts have recently been made to provide a practical application to consider possible asphyxia in cases identified as SIDS [7]. Fortunately the CESDI (Confidential Enquiry into Stillbirths and Deaths in Infancy) study in the United Kingdom has provided published recommendations. According to the CESDI guidelines deaths are classified within SUDI if they occur between 7 and 365 completed days of life and fulfill the following criteria:

Research and sudden infant death syndrome: definitions, diagnostic difficulties and discrepancies.

The diagnosis of causes of sudden infant death is an often complex and difficult process. Variable standards of autopsy practice and the use of different definitions for entities such as sudden infant death syndrome (SIDS) have also contributed to confusion and discrepancies. For example, the term SIDS has been used when the requirements of standard definitions have not been fulfilled. In an attempt to correct this situation recent initiatives have been undertaken to stratify cases of unexpected infant death and to institute protocols that provide frameworks for investigations. However, if research is to be meaningful, researchers must be scrupulous in assessing how extensively cases have been investigated and how closely cases fit with internationally recognized definitions and standards. Unless this approach is adopted, evaluation of research findings in SIDS will be difficult and the literature will continue to be beset by contradictions and unsubstantiated conclusions.

Changing trends in the diagnosis of sudden infant death.

A study of 114 consecutive cases of unexpected infant death that occurred in South Australia over a 5-year period from January 1994 to December 1998 was undertaken. There were 45 deaths attributed to sudden infant death syndrome (SIDS), 19 to natural causes, 21 to accidents. and 5 to homicides; 24 cases were listed as "undetermined." Although there has been a genuine and continued decline in SIDS numbers in this population, there has also been an increase in the diagnosis of cases of accidental asphyxia due to unsafe sleeping environments and of cases in which the family background and autopsy findings suggested more complex mechanisms. The change in diagnostic profile has followed the introduction of more rigorous clinical history review, death scene examination, and autopsy testing. Thus, although diagnostic outcomes have altered in this population, it is more likely the result of more careful interpretation of the extensive investigations that are now undertaken rather than arbitrary reclassification.

PATHOLOGIST AS GATEKEEPER: DISCRETIONARY DECISION‐MAKING IN CASES OF SUDDEN INFANT DEATH

In many cases of unexpected infant death the cause of death cannot be ascertained. It has become convention to call such cases ‘SIDS’ (Sudden Infant Death Syndrome). A simulation study of pathologists' decision‐making found that there were significant differences in the procedure adopted and the diagnosis of cause of death in such cases. It was found that their decision‐making was influenced by factors such as experience, training and most importantly, pathologists' own perception of their professional role. In an emotive area such as infant death the application of the SIDS label is frequently part of the social process of defining disease.