In 2007, the Office of the Chief Medical Examiner (OCME) began to use a new classification for infant deaths called Sudden Unexpected Infant Death or SUID . SUID is defined by the Virginia OCME as:
A diagnosis designated for infants under the age of 1 year. Sudden and Unexpected Infant Death
(SUID) is a diagnosis made in cases in which autopsy does not reveal a definitive medical or traumatic cause of death and the circumstances surrounding the death suggest that there is an associated risk factor for dying, such as unsafe bedding or co-sleeping, or some other external factor, but the contribution of this factor cannot be determined with certainty. The diagnosis may also be used in the situation where a medical disease is identified, but it is uncertain that this disease caused death.
The SUID definition is very close to the Sudden Infant Death Syndrome or SIDS definition:
Sudden Infant Death Syndrome (SIDS) is defined as the sudden death of an infant less than one year of age that cannot be explained after a thorough investigation is conducted, including a complete autopsy, examination of the death scene which includes no external risk factors, and review of the clinical history.
The major difference between SIDS and SUID is the presence or absence of an external risk factor such as an unsafe sleeping environment or a medical disease. All SIDS cases are classified as natural deaths with regard to manner of death. In contrast, the majority of SUID cases are classified as undetermined manner. In some rare cases, SUID cases are classified as natural deaths. In these cases, forensic pathologists use their discretion to analyze and interpret the circumstances of the case.
The numbers presented in this article differ slightly from the OCME’s 2007 Annual Report, which is available at: ( http://www.vdh.virginia.gov/medExam/documents/2008/pdfs/2007%20OCME%20Annual%20Report.pdf
).

Two SUID cases included in the annual report were removed for this study because the children were older than one year of age and therefore not infants.

Five cases classified as natural deaths by manner were described as “Other Natural Disease/Disorder” in the annual report. In this study they are combined with SUID cases because at least one risk factor was identified in the death investigation.
In 2007, there were 156 deaths of infants that fell under the jurisdiction of the OCME. The majority of these deaths were natural (Figure 1). Among the 70 natural cases, 41 or 58.6% were SIDS and five or 7.1% were
SUID with a natural manner of death. These five cases were combined with the other SUID deaths for the remainder of this report. Of the 53 undetermined infant cases, 41 or 77.4% were SUID. Of interest but not discussed or analyzed in this review were 13 accidental asphyxia deaths in infants. These deaths resulted from a suffocation, smothering or wedging event directly related to unsafe sleeping environments.
Figure 1. Total Infant Deaths by Manner, 2007
Undetermined
34%
Accidents
15%
Homicides
6%
Natural
45%
Examining the SIDS and SUID cases, males sustained more of the burden of these types of infant deaths than females. Among SIDS deaths, 2.2 males to every 1 female and among SUIDS, 1.6 males to 1 female (Figure
2). Excluding the one non-Virginia resident from rate calculations, the rate of SIDS deaths overall was 3.9 per
10,000 infants and 4.2 per 10,000 for SUID. For males the SIDS rate was 5.2 per 10,000 infant males and for females it was 2.5 per 10,000 infant females. Finally, for SUID, the rate for males was 5.2 per 10,000 and for females it was 3.3 per 10,000.

Figure 2. Infant Deaths by Cause of Death by Gender
28 28
30
25
20
18
Male
Female
13
15
10
5
0
SIDS SUID
Looking at SIDS and SUID deaths by age in months, there were more SUID cases in the early months of life, with the peak at one month. Among SIDS deaths, the majority occurred at 2 and 3 months of age (Figure 3).
Figure 3. SIDS and SUID by Age, 2007
14
14
12
12
10
SIDS
SUID
10
9
8
7 7
6
6
5
4
3 3
3
2 2 2
2
1 1
0 0
0
<
1
M o nt h
1
M on th
2
M on th s
3
M on th s
4
M on th s
5
M on th s
6
M on th s
8
M on th s
1
0
M o nt h s
White infants had the highest number of both SIDS and SUID deaths, but among all groups studied, black infants had the highest mortality rate (Figure 4)
†
. Black infants had a SIDS rate of 5.81 per 10,000 and a SUID rate of 7.0 per 10,000. The rate for black infants was 1.5 times greater than that of white infants, 3.7 times that of Asians, and 3.8 times that of Hispanics. This disparity continued in SUID cases where the black infant rate was 1.6 times that of white infants, 4.4 times that of Asian infants, and 9.2 times that of Hispanic infants.
Figure 4. Infant Deaths by Cause of Death by Race/Ethnicity
30 8
26
7
25
23
6
20
18 5
15
15 4
3
10
5
2
1 1 1
0
SIDS SUID
Asian
Asian Rate
Black
Black Rate
Hispanic
Hispanic Rate
White
White Rate
†
Hispanics were of any race while Asian, black, and white races included those who were not of Hispanic ethnicity.
2
1
0

The OCME has taken a critical step in classifying infant deaths by separating SUID and SIDS; this is not a distinction made in international classification schemes. At the same time, separation of these two categories can be challenging and is not yet fully institutionalized or stable in the practices of all forensic pathologists. As a result, there is not a clean separation between the two categories. The role of a risk factor, for example a natural disease progression, will be assigned a different weight by different pathologists. In the end, some SIDS cases and some SUID cases are described with a natural disease (Figure 5). The presence of an unsafe sleeping risk factor should tip the scales and make a case SUID instead of SIDS. Two additional considerations shape this outcome. First, the definition and use of SUID is new in definition and in application to infant death cases.
Second, the presence of an unsafe sleeping condition is a statement of fact drawn from a thorough death investigation, but it does not clearly explain the role it played in an infant’s death. In some SIDS cases with an unsafe sleeping practice, for example, a forensic pathologist made note of the unsafe risk factor but also concluded that it had no effect on the infant. In this review and in the interest of full disclosure any infant death case in which a risk factor was mentioned, regardless of its contribution to the infant death, was recorded for this review.
Figure 5. Infant Deaths by Cause of Death by External Risk Factor
None
Unsafe Sleeping Practice
Natural Disease
Drugs
37
40
35
30 25
25
20
15
10
12
6
4
2
5
0
1
0
SIDS SUID
Most Virginia Department of Health Districts were impacted either by SIDS cases (Figure 6) or by SUID cases
(Figure 7). Excluding most of the highly populated areas, in general if a Health District had SIDS cases it did not have SUID cases and vice versa.
Figure 6.
Cases

Cases
Figure 7.
This review represents the first year of data where the SUID cause of death was applied statewide. Additional years and a more stable definition applied to all applicable cases will hopefully help to further separate SIDS and SUID deaths. This will also support data-driven prevention strategies for these two causes of death.
Prevention Tips ( http://www.vahealth.org/Injury/topics/suffocation.htm
)

Always put your baby to sleep on his or her back, not the stomach.

Always place baby to sleep in a safety-approved crib (look for a Juvenile Products Manufacturers
Association certification label) with a firm tight-fitting mattress and tight-fitting bottom sheet.
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Never let your baby sleep on soft surfaces like waterbeds, sheepskin rugs, pillows or comforters.

Remove quilts, comforters, pillows, and other fluffy bedding and toys from baby's sleep area.
Additional Information

Virginia Department of Health: http://www.vahealth.org/Injury/data/datareports.htm
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American Academy of Pediatrics: http://www.aap.org/healthtopics/Sleep.cfm

Centers for Disease Control & Prevention: http://www.cdc.gov/SIDS/index.htm

SIDS Alliance: http://www.sidsalliance.org/
OCME Contact Information
Anna Noller, PhD
804.786.6063
Anna.Noller@vdh.virginia.gov