Transcript SIDS: Introduction

Sudden Infant Death Syndrome (SIDS)
Highlights of its Epidemiology and
History
BIOS601: Dec. 5, 2007
SIDS: Introduction
• Definition: “The sudden death of an infant under one year of age
which remains unexplained after thorough investigation, including
the performance of a complete autopsy, examination of the death
scene, and review of the clinical history”
• SIDS continues to be the leading cause of death for infants aged
between 1 month and 1 year in developed countries:
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–
–
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Lowest:
Japan (0.09/1000), The Netherlands (0.1/1000)
Highest:
New Zealand (0.8/1000)
Intermediate:
USA (0.57/1000), UK (0.41/1000)
2162 infants died of SIDS in the USA alone (2003).
• “An elusive disease that strikes not only the child, but his whole
family”
NICHD (National Institute of Child Health & Human
Development)
Issues of Definition
• “In the technical medical language, a ‘syndrome’ refers only to the
set of detectable characteristics. A specific disease, condition, or
disorder may or may not be identified as the underlying cause.”
(Wikipedia)
• “… diagnosis of SIDS is a diagnosis of exclusion, and the means of
exclusion are imperfect … a diagnostic dustbin” (Emery)
• “the diagnosis of cot death … excused all concerned from any
defect in care, diagnosis, and treatment’ and ‘facilitated the
development of parent support groups and the raising of money for
research
• SIDS vs pneumonia (Loberg and Naess, 1991), 55% of 1,144 cases
eliminated (Haas 1993),1.6% of 400 cases reclassified (ValdesDapena, 1988)
SIDS: Epidemiology
Age Structure
Seasonality
Month of Cot Deaths
60
# Occurences
80
70
60
50
40
30
20
10
0
50
40
30
20
10
Age (Months)
9+
10
+
11
+
8+
6+
7+
4+
5+
3+
0
1+
2+
01
# Occurrences
Age of Cot Deaths
J
F
M
A
M
J
J
A
S
O
N
D
Month of Year
(SIDS deaths, Auckland, New Zealand, 1970-1979)
- Gender, birth order, pacifiers, prior fetal loss, time of day, regional differences,
race and ethnicity, family recurrence
- Cigarette smoking, bed-sharing, swaddling, breastfeeding, socioeconomic
SIDS: Pathology
Paradox: The baby is observed to be clean and well-cared-for with apparently
good to excellent state of development, nutrition, and hydration.
External Findings: Moderate amount of cyanosis, mucoid fluid in the mouth
and nostrils (> 50% of cases), soiled diapers
Internal Findings: Intrathoracic petechiae: observed more consistently in SIDS
cases than in any other condition at this age (>50%), some pulmonary
congestion and edema, some inflammation of the upper respiratory tract
SIDS: Final Pathways
Cardiovascular
Apnea
Epidemiology
Pathology
Causality?
Mechanism
Hill’s Criteria …
SIDS Timeline
Old Testament (I Kings 3:19), Middle Ages
mid 1800s (rise and fall of thymic theory; negligence; other causes)
1942-1953 (Werne and Garrow, SIDS as a distinct medical entity)
1953+ (accumulation of epidemiologic and pathologic data, as well
as a ‘parade of theories’).
1969 (definition of SIDS established)
Early 1990s (identification of acceptance of sleeping position as the most
powerful risk factor, followed by a worldwide decline in SIDS incidence)
2007 (still the leading cause of infant mortality, but with changing
epidemiology)
Sleeping Position Timeline
1950-1985 – sleep position observed but not noticed in SIDS studies
1972 – public campaign in the Netherlands against the supine position
1985 – sleep position first clearly raised as a possible important factor
(Davies, Hong Kong)
1986 – 1st study with clear recommendation against the prone sleeping
position (Beal), with subsequent drop in SIDS rates
1989 – 1st thorough analysis of the effects of the prone sleeping position
(deJonge, Netherlands)
1991 – 1st prospective study of the prone position (Dwyer, Tasmania)
1991-1994 – controversy and delay in policy implementation in the
United States
2007 – still the leading cause of infant mortality, but with changing
epidemiology
1991-1994 SIDS controversy in the United States
• 1991 Guntheroth and Spier (JAMA)
• April 15, 1992 AAP press release followed by report in Pediatrics
• Criticisms:
– Hunt and Shannon (1992)
– SIDS Alliance (Mary Willinger)
– Orenstein (1992)
• Sources of epidemiological controversy: statistics, literature,
causality vs. association, intuition, population differences,
iatrogenesis, levels of rigour. “Hindsight is 20/20”
• “willingness to ignore 2000-3000 infant deaths per year”
• National campaign announced by Surgeon General
AAP Task Force on Infant Positioning and SIDS
(Pediatrics, 1992)
Four modifiable and other major risk factors for cot death:
The New Zealand study
(Mitchell et. al., 1992)
SIDS rates in Avon compared with England and Wales, during 1984-2003
SIDS: An ongoing area of investigation
# SIDS articles (Pubmed)
350
300
6335 Hits
# Articles Found
250
200
150
100
50
0
1970
1975
1980
1985
1990
Year
1995
2000
2005
2010
SIDS: An epidemiological study in progress
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Sudden infant death syndrome: another year of new hope but no cure.
(Curr Opin Pulm Med. 2007 Nov;13(6):497-504)
Risk of sudden infant death syndrome with parental mental illness.
(Arch Gen Psychiatry. 2007 Nov;64(11):1323-30 )
Unexpected sudden death related to medullary brain lesions
(Acta Neuropathol. 2005 May;109(5):554-5. Epub 2005 May 18)
Vitamin A and sudden infant death syndrome in Scandinavia 1992-1995.
(Acta Paediatr. 2003;92(2):162-4)
Enzyme-linked immunoassay for respiratory syncytial virus is not predictive of
bronchiolitis in sudden infant death syndrome.
(Pediatr Dev Pathol. 1998 Sep-Oct;1(5):375-9)
SIDS and chaos.
(Med Hypotheses. 1994 Jan;42(1):11-2)
Passive fear--a possible cause of sudden infant death?
(Tidsskr Nor Laegeforen. 1986 Apr 30;106(11):898-902)
Structure of periadrenal brown fat in childhood in both expected and cot deaths
(Arch Dis Child. 1978 Feb;53(2):154-8)
etc. …..
Conclusions
• Risk factors vs. causality (Hill’s criteria)
• Importance of policy in epidemiology
• Epidemiology changes
• Sources of epidemiological controversy
• Another breakthrough?
The continuing decline in SIDS mortality
(Mitchell, 2007)