The epidemiology of sudden infant death syndrome

Background: Twins compared to singletons are at increased risk of sudden infant death syndrome (SIDS). Aims: To compare the epidemiology of SIDS in twins and singletons and to test the hypothesis that monozygous (MZ) were at greater risk of SIDS than dizygous (DZ) twins. Methods: Data from the Office for National Statistics on all registered live births and infant deaths with registered cause of death "sudden unexpected death in infancy" in England and Wales from 1993 to 1998 were obtained, together with the registered birth weight and, for twins, whether they were of like or unlike sex. Results: The crude relative risk of SIDS in twins is twice that in singletons. There has been a significant temporal decline in SIDS mortality. There is also a significant increase in risk with decreasing birth weight for both twins and singletons. The birth weight specific risk of SIDS in all except for those ≥3000 g is greater in singletons than in twins. There is no significant difference in risk of SIDS in like compared with unlike sex twins. Conclusions: In spite of a lower risk of SIDS in twins compared with singletons for each birth weight group <3000 g, one component of the higher crude relative risk of SIDS in twins is attributable to the higher proportion of twins that are of low birth weight. A second component is the higher risk in twins compared with singletons for those of birth weight ≥3000 g. Like sex are at no greater risk than unlike sex twins, which suggests that zygosity is not a significant factor in SIDS.     

Clinical implications of sudden infant death syndrome epidemiology

The diagnosis of sudden infant death syndrome (SIDS) is less than 100% certain in any given instance. Approximately 90% of all SIDS have occurred by age 6 months. A visual aid consisting of 1,000 dots helps in communicating numerical information such as 'rates' to parents (and others as well). The annual and seasonal occurrence patterns are independent of so-called SIDS risk factors. A single, major gene defect cannot account for SIDS but the root cause may be genetic (polygenic). Recent estimates of sibling risk to SIDS indicate that earlier estimates were inflated. Use of apnea monitors to prevent SIDS has no basis in fact but may provide emotional support. DTP immunization does not cause SIDS.     

The epidemiology of sudden infant death syndrome.

BACKGROUND: Twins compared to singletons are at increased risk of sudden infant death syndrome (SIDS). AIMS: To compare the epidemiology of SIDS in twins and singletons and to test the hypothesis that monozygous (MZ) were at greater risk of SIDS than dizygous (DZ) twins. METHODS: Data from the Office for National Statistics on all registered live births and infant deaths with registered cause of death "sudden unexpected death in infancy" in England and Wales from 1993 to 1998 were obtained, together with the registered birth weight and, for twins, whether they were of like or unlike sex. RESULTS: The crude relative risk of SIDS in twins is twice that in singletons. There has been a significant temporal decline in SIDS mortality. There is also a significant increase in risk with decreasing birth weight for both twins and singletons. The birth weight specific risk of SIDS in all except for those > or =3000 g is greater in singletons than in twins. There is no significant difference in risk of SIDS in like compared with unlike sex twins. CONCLUSIONS: In spite of a lower risk of SIDS in twins compared with singletons for each birth weight group <3000 g, one component of the higher crude relative risk of SIDS in twins is attributable to the higher proportion of twins that are of low birth weight. A second component is the higher risk in twins compared with singletons for those of birth weight > or =3000 g. Like sex are at no greater risk than unlike sex twins, which suggests that zygosity is not a significant factor in SIDS.     

The epidemiology of sudden infant death syndrome and attacks of lifelessness in Sweden

Infants who died showing the syndrome of sudden infant death (SIDS) and infants who survived attacks of lifelessness (AL) were examined in a prospective epidemiological multicentre study over 24 months covering close to 40% of all births in Sweden. Seventy SIDS cases and 34 cases of AL were observed, giving an incidence for SIDS of 0.94/1000 and for AL of 0.46/1000. This SIDS incidence is higher than that observed during the seventies. The boy/girl ratio was 1.4:1 for SIDS and 1.6:1 for AL. The age distribution for AL resembled that for SIDS. Similarities were also seen with regard to place of occurrence. Sixty per cent of the SIDS cases occurred during the daytime/evening. Twenty-nine per cent of the infants with AL had more than one apneic spell during the three-day-period around the attack, indicating a period of respiratory instability, but only 12% had such spells later on. None of the infants who had had AL died from SIDS. The possible relationship between AL and SIDS is discussed.     

Defining the sudden infant death syndrome

Sudden infant death syndrome (SIDS) is a term that was first proposed in 1969 for a distinctive subgroup of unexpected infant deaths that occur during the postneonatal period with relatively consistent clinical, epidemiological, and pathological features. This term played an important role by focusing attention on a major category of postneonatal infant death, providing support to grieving families, and diminishing the guilt and blame characteristic of these deaths. Unfortunately, the application of this term has become increasingly controversial. Some have applied it too liberally, and others not at all. According to the definition proposed in 1969, despite slight changes suggested in 1989, SIDS remains a diagnosis of exclusion. Although this syndrome has several distinctive features, including age distribution and apparent occurrence during sleep, there has been reluctance to include these features in the definition. The problems created by the lack of an adequate definition are discussed. A 2-tiered approach is suggested, with a more general definition intended primarily for case management and death administration, and a more restrictive one intended primarily for research purposes, which distinguishes those deaths closely fitting the classic SIDS profile from those with one or more less typical features.     

Update on sudden infant death syndrome

PURPOSE OF REVIEW: With the introduction of the Back to Sleep campaign by the American Academy of Pediatrics in 1992, the incidence of Sudden infant death syndrome has decreased by almost 50%. Despite this success, SIDS continues to be the most common cause of unexplained infant death in Western countries. This article will briefly review the definition, etiology, and risk factors of SIDS. Attention will then focus on ways to target specific associated risk factors and at risk populations to promote a continued downward trend in the number of SIDS deaths. RECENT FINDINGS: Recent literature in SIDS research has focused on identifying infants at continued risk for SIDS. Children attending child care centers have an increased risk for SIDS, which is of particular concern as the number of infants in child care continues to rise. The reasons for this, along with strategies to decrease this risk, will be reviewed. In addition, the SIDS rate among black infants continues to be more than twice that of white infants. A review of the reasons for this disparity and ways to intervene through targeted campaigns will be discussed. Recent data has also suggested that the prevention of SIDS should not be an indication for use of home cardiorespiratory monitoring. The use of home monitoring may be warranted for some infants and will be reviewed. SUMMARY: Our jobs as pediatricians should be to ensure that the incidence of SIDS continues to decline. This can be done through parent education at each and every well child visit, lobbying to enforce state law to implement SIDS education campaigns for child care centers and within African-American communities, and continued review of the most current literature in SIDS research to keep ourselves current and well informed.     

Dummies and the sudden infant death syndrome

The association between dummy use and sudden infant death syndrome (SIDS) was investigated in 485 deaths due to SIDS in the postneonatal age group and compared with 1800 control infants. Parental interviews were completed in 87% of subjects. The prevalence of dummy use in New Zealand is low and varies within New Zealand. Dummy use in the two week period before death was less in cases of SIDS than in the last two weeks for controls (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.57 to 1.02). Use of a dummy in the last sleep for cases of SIDS or in the nominated sleep for controls was significantly less in cases than controls (OR 0.44, 95% CI 0.26 to 0.73). The OR changed very little after controlling for a wide range of potential confounders. It is concluded that dummy use may protect against SIDS, but this observation needs to be repeated before dummies can be recommended for this purpose. If dummy sucking is protective then it is one of several factors that may explain the higher mortality from SIDS in New Zealand than in other countries, and may also explain in part the regional variation within New Zealand.     

Gender and the sudden infant death syndrome

Abstract A nationwide case-control study compared the prevalence and magnitude of risk factors for sudden infant death syndrome (SIDS) in male and female infants. The risk factors of SIDS and their magnitude for males and females are very similar. After adjustment for potential confounders male infants had a 1.42-fold (95% CI = 1.04, 1.94) increased risk of SIDS compared with females. Risk factors identified in most epidemiological studies are not the reason for the increased SIDS mortality seen in male infants.     

Psychosocial factors and sudden infant death syndrome

Sudden infant death (SID) is a multifactorial syndrome in which the role of psychosocial factors should be taken into consideration. Deep changes in mores and in the way infants are cared for occurred in the second half of the XXth century. Fragmentation of the traditional family has led to increased isolation of the infant. Significant changes have also occurred in the status of women and have translated into increasingly early separation of the mother from her baby. These factors, together with economic difficulties that carry a risk of preterm birth and intrauterine growth retardation, may be involved in the genesis of SIDS. Difficulties experienced by the mother in relating with her child during the first few months of life, a critical period for interaction, may also play a role. Prevention of SIDS should take psychosocial factors into account and attempt to minimize their effect.     

Febrile convulsions and sudden infant death syndrome

It has been suggested that sudden infant death syndrome (SIDS) and febrile convulsions are related aetiologically. We compared the risk of SIDS in 9877 siblings of children who had had febrile convulsions with that of 20 177 siblings of children who had never had febrile convulsions. We found no support for the shared susceptibility hypothesis.