PEDIATRICS Vol. 122 No. 4 October 2008, pp. 869-870 (doi:10.1542/peds.2008-1924)
COMMENTARY |
Recurrence of Sudden Infant Death Syndrome
Pediatrician (Retired), Yorkshire, United Kingdom
Abbreviations: SIDS, sudden infant death syndrome • GMC, General Medical Council
Recent court cases in the United Kingdom have drawn attention to recurrence of sudden infant death syndrome (SIDS) within a family, with estimates of its frequency ranging from 1 in 73000000 (the figure for which Meadow was censured by the General Medical Council [GMC]) to 1 in 200 (the figure now favored by the United Kingdom media). In an attempt to arrive at a more balanced estimate, we reexamined the 8 published studies of recurrent SIDS conducted in Australia, Norway, the United Kingdom, and the United States between 1965 and 1999.1
We assessed the studies by using 3 criteria: completeness of ascertainment; accuracy of diagnosis; and matching of controls. Ascertainment was usually imperfect but not critical. Diagnosis cannot always be certain for an entity defined by exclusion. In the 40 years since the term SIDS was introduced, a number of familial disorders that may cause unexpected death in infancy, notably defects of fat metabolism, have been identified. In the earlier studies, such disorders could not have been excluded and the deaths they caused would have been attributed to SIDS, falsely elevating the recurrence rate. Even today not all the relevant tests may be performed, and it is possible that other such conditions remain to be discovered. It is known that a parent who has caused the death of an infant may go on to cause another,2 and repeated covert homicide, if undetected, may be misdiagnosed as recurrent SIDS. Covert homicide is extraordinarily difficult to identify, and before Emery's publications in 19853 the possibility was seldom considered. Finally, no study of recurrent SIDS has had controls matched for degree of risk, which has now been shown to vary 40-fold between different groups.4 Without stratification for risk, recurrence in high-risk groups will elevate the apparent overall recurrence rate even if the risks for each group remain constant.5
We concluded that the flaws in these studies invalidate the authors' estimates of the risk of recurrent SIDS, and the figures suggested are mainly too high. We accept, however, that on theoretical grounds a family who has lost an infant to SIDS may well be at increased (but unquantifiable) risk because of the persistence of genetic and environmental influences.6
The background to the more extreme estimates reveals the abysmal quality of the debate in the United Kingdom. The figure of 1 in 73000000 comes from a report of the quasi-official Confidential Enquiry Into Stillbirths and Deaths in Infancy (CESDI),4 which Meadow had seen in draft. The relevant passage suggested, with qualifications, that the risk of having 2 SIDS deaths in a low-risk family was the square of the risk for a single death in that group; this is an invalid exercise, because the 2 events are not independent. Although the GMC was told that Meadow had misinterpreted this passage,7 the Confidential Enquiry Into Maternal and Child Health, which succeeded CESDI, has since appended a note on its Web site to acknowledge the error.8
The figure of 1 in 200 seems to have arisen from a mistake by the GMC's barrister. Extrapolating from published studies, he suggested that the risk of a second SIDS death in a family that has already had one is 1 in 75 (1 in 200 for a low-risk family). Unfortunately, he then confused this risk with that of having 2 deaths in a family de novo, comparing 1 in 75 with 1 in 73000000.7 The media have followed suit. Besides the injustice and scientific inaccuracy, such a high estimate causes needless anxiety to parents.
What, then, should we say to parents who have lost an infant unexpectedly and are worried about recurrence? Because risk varies so widely between families, advice must be individually tailored. Above all, it is essential that the first death be thoroughly investigated, looking particularly for conditions that might recur, such as familial disease, covert homicide, or major risk factors for SIDS.4 If these can be excluded and the family takes reasonable precautions, they can be assured that the chance of recurrence is very small, much smaller than is suggested by the media and, for most parents, too small to deter them from another pregnancy. It is important, however, to identify families at high risk (whose infants are vulnerable to death resulting from other causes as well as SIDS) and give them all possible support.
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FOOTNOTES |
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Accepted Jul 1, 2008.
Address correspondence to Christopher Bacon, FRCPCH, Glebe House, Danby Wiske, Northallerton, North Yorkshire DL7 OLY, UK. E-mail: chrisandheatherbacon{at}ukonline.co.uk
Financial Disclosure: Dr Bacon was formerly a medical adviser to the Foundation for the Study of Infant Deaths and wrote a report for the legal team that defended Professor Meadow at the General Medical Council.
Opinions expressed in these commentaries are those of the author and not necessarily those of the American Academy of Pediatrics or its Committees.
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REFERENCES |
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- Bacon CJ, Hall DBM, Stephenson TJ, Campbell MJ. How common is repeat sudden infant death syndrome?
Arch Dis Child. 2008;93
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[Abstract/Free Full Text] - Firstman R, Talan J. The Death of Innocents. New York, NY: Bantam; 1997
- Emery JL. Infanticide, filicide, and cot death.
Arch Dis Child. 1985;60
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[Free Full Text] - Fleming P, Blair P, Bacon C, Berry J. Sudden Unexpected Deaths in Infancy: The CESDI SUDI Studies 1993–1996. London, United Kingdom: Stationery Office; 2000
- Campbell MJ, Hall D, Stephenson T, Bacon C, Madan J. Recurrence rates for SIDS: the importance of risk stratification. Arch Dis Child. 2008. doi:10.1136/adc.2007;121350
- Hill R. Multiple sudden infant deaths: coincidence or beyond coincidence? Paediatr Perinat Epidemiol. 2004;18 (5):320 –326[CrossRef][Web of Science][Medline]
- General Medical Council, Fitness to Practise Panel (Professional Conduct). Case of Meadow, Professor Sir Samuel Roy. Clark-Glass M, chair. London, United Kingdom: General Medical Council; 2005
- Confidential Enquiry Into Maternal and Child Health. CESDI SUDI report. Available at: www.cemach.org.uk/Publications/CESDI-SUDI-Report-(1).aspx. Accessed June 26, 2008
PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics
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