Sudden infant death syndrome

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Sudden infant death syndrome

• Mark Ford
• GPR

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Overview

• Epidemiology
• Pathology
• Risk factors and current advice
• Evidence for current advice
• Implications for practice

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Definition

• Sudden infant death syndrome (SIDS) is the sudden
  death of an infant aged under 1 year that remains
  unexplained after review of the clinical history,
  examination of the scene of death, and postmortem
• Most deaths occur during the first 6 months
• Leading cause of death in infants over 1 month of
  age. Rare after 5 months

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Incidence

• Each year around 350 babies die from SIDS in the
  UK
• 1999 figures-0.57 per 1000 live births
• Incidence falling since 1989
• Numbers fallen since Reduce the Risk campaign
  in 1991 (revised 1996 2000)
• Numbers now stabilised

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Pathology

• No pathognomonic features
• Petechial haemorrhages in 90 of cases
• Pulmonary oedema often present
• Evidence of low grade asphyxia in 2/3 of cases
• Intracranial abnormalities
• Mutations of cardiac sodium gene

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Risk Factors

• Maternal/ antenatal risk factors
• Infant risk factors
• Possible genetic/ biological risk factors

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Prone sleeping

• Link to sleeping position first considered as
  early as 1965
• Proposed physiological benefits of supine
• No RCTs or systematic reviews comparing advice
  to avoid prone sleeping and not
• Evidence-1 non-systematic review 12
  observational studies
• Back vs side sleeping

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Smoking

• Mechanism unclear
• Effect of smoking when pregnant
• Some studies link passive smoking
• Postnatal smoking only may be an independent risk
  factor (small no. make studies difficult)
• Evidence- 1 non-systematic review 4
  observational studies

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Over-heating

• Initial reports largely circumstantial
• Subsequent case-control studies suggest link
• Heating interacts adversely with other important
  factors such as prone sleeping and infection
• ? overheating increasing the risk of SIDS only
  when infants were sleeping prone
• Evidence-1 non-systematic review and one
  observational study

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Bed sharing

• Bedsharing increases risk when parent smokes, has
  consumed alcohol, or has taken medicines/ illegal
  drugs
• Bed sharing may increase risk in young babies,
  even when parents dont smoke
• DOH recommends that babies sleep in the same room
  as parents for 6 months
• Evidence- one observational study/ early
  case-control studies

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Breast Feeding

• Association inconclusive
• Some studies suggested protective effect, but ?
  specifically due to breast-feeding advice
• Insufficient evidence to support link at present
• Still to be encouraged as has other benefits

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Soothers

• Possible effect on infants sleep environment
• Recent study in BMJ (7th January). 3 year
  case-control study of 185 infants in California
• Main outcome measure use of dummy determined by
  interview
• 50 of eligible cases and 41 of eligible
  controls participated
• Looked at maternal/ infant characteristics and
  sleep environment

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Soothers cont.

• Also looked at dummy use in relation to selected
  risk factors for SIDS
• Suggested 90 reduction in risk
• Reduction in risk appeared greater in infants
  with adverse sleep conditions, but did not
  achieve statistical significance
• Causal effect not identified

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Soothers cont.

• Problems with study-
• ?Low uptake
• ?Uncertainty generated by non
  participants
• ?Relied on maternal reporting of index sleep

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Summary

• Avoid prone sleeping
• Avoid smoking, overheating, bed sharing
• Evidence inconclusive for breast feeding, soft
  bedding and soother use

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Questions?