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

Abstract

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: