DP Davies, P Davis

Introduction

The last five years or so have seen a remarkable 66% fall in the number of deaths attributed to the Sudden Infant Death Syndrome (SIDS) in Britain (from around 2 per thousand live births to 0.5 per thousand, a reduction of over 1000 deaths per year) and in many other western countries.¹

Much of this reduction in Britain is attributed to the simple four point advice included in the 'Back to Sleep' campaign that was launched in December 1991, especially the importance of avoiding prone sleeping.² Readers of this Journal will recall some research carried out in Hong Kong in the 1980s that contributed to the greater universal recognition of the importance of avoiding prone sleeping.³ But about 10 babies a week are still falling victim to SIDS⁴ in Britain which remains the largest category of death in babies >1 week to 12 months. Why is this? What is it about this all too large 'residuum' of death? In 1993, we highlighted a disturbing prevalence in South Glamorgan (Wales) of serious poverty and disadvantage in families of SIDS victims.⁵ Others also recorded their concern that SIDS was becoming even more closely linked with social deprivation than in the past. This paper extends this study of our local experience of recent SIDS cases in order to help better understand the continuing tragedy of unexplained deaths in infancy.

Methods

Details of individual cases of sudden unexpected deaths were collected prospectively by one of us (PD) who routinely contacts the primary care teams to gather information on sudden, unexpected deaths and liases with the paediatric pathologist and coroner. All childhood deaths in South Glamorgan are notified to the central Child Health Computer Office. A bereavement support team in Community Child Health, led by PD, has been established since 1992 in order to provide immediate bereavement counselling to families after sudden unexpected childhood deaths and with a secondary role to assist the collection of information on these deaths by means of a detailed unstructured discussion with their health visitor. Observations on 26 consecutive children dying of SIDS form January 1993 to January 1997 are presented here.

Result

Incidence:

In the three years of this study, South Glamorgan had a rate of SIDS of 1.1 per 1000 live births from 1993-1995 which was slightly higher than the then national average. There are no specific demographic aspects of South Glamorgan to explain this: the socio-economic distribution of the population and standard mortality rates for other conditions generally relate closely to the national average.

Age and gender:

Age at death was similar to historically reported patterns with 16 deaths occurring between 1 and 6 months with a peak at 1 to 3 months and fifteen of the twenty infants being male.

Month of birth and death:

Previous reports have suggested that babies born in the winter months are at greater risk of SIDS. This was not our experience with most of the children born in spring or early summer. Neither did we see the anticipated seasonal variation in deaths: analysis or coroner's records for the period 1979-91 showed a 2/1 ratio of deaths in winter/summer.

Socio-environmental factors:

Twenty-four of the 26 deaths occurred in smoking households. Drugs or alcohol abuse were an identified problem in 7 families; 14 were living in severe social deprivation (judged subjectively by one of us (PD); 7 infants died in bed with their parents; 11 of the mothers were single and not living in a stable relationship. In six families there was a history of child abuse or neglect in the index child or siblings, one infant was on the child protection register. Only one child had been breast fed.

Discussions

South Glamorgan has shared the falling incidence of SIDS in Britain. Our rate in the years of this study is slightly higher than the national value but further comment on this is unlikely to be helpful in view of the small numbers of victims. What is impressive about our findings is the sizeable amount of poverty, disadvantage and child abuse in victims' families and a total absence of deaths in professional, managerial and skilled workers' families. The chaos and lack of order in the majority of the victims' families was impressive. A few of these families have come under intense scrutiny by the coroner and by child protection agencies following the death, with much resulting stigmatisation but no easily definable cause of death being found. It is the opinion of paediatricians who have been aware of trends in sudden infant death over many years in our district that the social factors observed in our cases represent a very worrying deviation from the situation that existed in the past.

Several new initiatives are being introduced by the Foundation for the Study of Sudden Infant Death to help the incidence of SIDS continue to fall. There is to be a more thorough investigation into intrauterine growth retardation as a major risk factor and a greater emphasis on how infants are looked after (especially for example whether co-sleeping is a risk or protective factor) and the relationships that develop between mother and baby. We believe this last behavioural approach to be especially important: after all, the major risk factor that has been modified in the current campaign, sleeping posture, derives more from examining the care-giving environment than the precise definition of patho-physiological mechanisms. It is essential that we continue to investigate in detail the undoubted strong links that exist between social adversity, disadvantage and increased risk of SIDS which must include ensuring that the 'Back to Sleep' campaign is effectively targeted and complied with by those especially vulnerable families living in poor socioeconomic circumstances.

Summary

In 1993 to 1997 there were 26 SIDS victims in the County of South Glamorgan - an incidence of 1.1 per 1000 live births. Especially significant in the families of these infants was the large amount of social disadvantage, substance abuse (smoking, drugs, alcohol) and a history of child abuse or neglect in the index child or sibling. There was an absence of death in professional, managerial and skilled workers' families. As well as new initiatives looking in detail into infant care practices, if the 'residuum' of unexplained infant deaths is to be reduced there needs also to be further research into the links that undoubtedly exist between social disadvantage and increased risk of SIDS.

References

1. Cot Death in Britain: Incidence reduced by two thirds in five years. BMJ 1995;310:4-.

2. Dept of Health: Sleeping posture of infants and the risk of cot death (Sudden infant death), London. Dept of Health 1991 (Professional letter: PL/CMO (91) 16:PL/CMO (91)(11).

3. Lee NNY, Chan YF, Davies DP, Lau E, Yip DCP. Sudden infant death syndrome in Hong Kong. Confirmation of low incidence. BMJ 1989;298:72-.

4. FSID (London) Media Release 2/96.

5. Davis P, Davies DP, Webb E. Don't be complacent about cot death. BMJ 1993;307:441-.