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 Journal
Review
by
Alex Kenton, MD
Malloy,
MH. Trends in postneonatal aspiration deaths and reclassification
of sudden infant death syndrome: Impact of “Back to Sleep” Program.
Pediatrics 2002; 109(4): 661-665.
Introduction:
Despite the belief that prone positioning of infants could lead
to aspiration, in 1992 the American Academy of Pediatrics Task
Force on Infant Positioning and SIDS recommended placing infants
on their backs for sleep. This study sought to delineate whether
there is a relationship between aspiration-related deaths and
supine positioning. The study also examined whether the decrease
in SIDS-related deaths could be attributable to a reclassification
as to the cause of death.
Methods: Data were obtained from linked birth and infant
death statistic tapes for the United States for 1991, ’95 and
’96. Because of a lack of linked tapes for 1992–1994, U.S. vital
statistic natality and mortality tapes were used for those years.
For births that were not linked, the number of births was obtained
from natality tapes and causes of death were obtained from mortality
tapes. ICD-9 codes for underlying causes of death included SIDS,
aspiration, asphyxia, respiratory failure, and accidental suffocation
in bed or cradle. Other broad categories of underlying causes
of death also were examined to determine the major causes of death
that could account for the drop in SIDS death. Demographic and
infant birth information was used from linked files in 1995 and
1996 to examine characteristics of infants who died of SIDS compared
to those who died of suffocation. Infants >500 grams were used
for the study. Postneonatal mortality rates were calculated by
dividing number of deaths that occurred beyond 28 days of life
by the number of live births. Proportionate mortality ratios were
also calculated for specific conditions. Significant trends in
postneonatal mortality rates and postneonatal mortality ratios
were determined using chi-square analysis. Logistic regression
was used to determine significant population characteristics of
the infants that died of SIDS compared with those infants who
died of suffocation.
Results:
The study found that during the six-year period (1991–1996) postneonatal
mortality decreased 21.9% (P<0.001). SIDS postneonatal mortality
declined 38.9% while the neonatal SIDS mortality rate declined
28%. Postneonatal aspiration-related deaths also decreased (P=0.01).
There were no significant increases in the postneonatal mortality
rate due to asphyxia or respiratory failure. Suffocation was the
only cause of death for which a significant increase was shown
for which a portion of previous SIDS deaths might be reclassified.
The causes of death to which SIDS might be reclassified accounted
for <2% of the total annual postneonatal mortality.
Discussion: This study supports the observations of others
that mortality due to aspiration decreased at the same time that
the incidence of supine positioning rose. Although a significant
increase was seen in the mortality rate due to suffocation, that
rate remained well below the SIDS rate (0.0093 per 1000 live births
compared to 0.72 per 1000 live births in 1996). Thus, the drop
in SIDS mortality is related to supine positioning.
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