Sudden infant death syndrome in Indigenous and non-Indigenous infants in north Queensland, 1990-1998

OBJECTIVE: To compare the epidemiology of sudden infant death syndrome (SIDS) in Indigenous and non-Indigenous infants in north Queensland, and to assess the quality of data recorded for SIDS deaths. METHODS: Records were obtained for SIDS cases from all coronial courts in north Queensland from 1990 to 1998. Demographic characteristics, ethnicity, age at death, sleeping and feeding patterns, smoking incidences and autopsy findings were compared. Incidences, medians and univariate associations were generated where appropriate. RESULTS: There were 83 248 live births for the 9-year period; 71 389 non-Indigenous and 11 859 Indigenous births. There were 69 SIDS deaths (0.83 per 1000 live births). Overall, recording of demographic and death scene data was poor. Thirty-eight autopsies (55%) were performed by specialist pathologists. There were 22 (32%) non-Indigenous and 22 (32%) Indigenous SIDS deaths (25 ethnicity unknown), giving an estimated relative risk of 2.82 (95% CI 2, 4). Median age at death was 13.1 weeks (range 1-83 weeks) with 14% of deaths occurring in the neonatal period for both groups. Sleeping position was not recorded in 42% of cases and co-sleeping was not recorded in 27% of cases. Bed sharing was more common amongst Indigenous infants. Fifty-two per cent of SIDS cases occurred in the wet season and 48% in the dry season. CONCLUSIONS: Data recorded for SIDS deaths in north Queensland are poor, preventing specific conclusions concerning SIDS risk factors. However, SIDS rates may be up to three-fold higher in the Indigenous population. A uniform system of post-mortem and death scene data reporting is needed urgently.     

Autopsies of sudden infant death syndrome—classification and epidemiology

An enquiry into sudden infant death syndrome (SIDS) in 1987 furnished us with detailed epidemiological data for 281 cases that underwent a thorough post-mortem examination. This analysis uses these data to evaluate the role the autopsy plays in explaining sudden death. The cases were classified into three diagnostic groups: explained causes of death (group 1), unexplained deaths with anomalies (group 2), and no anomaly (group 3). These 281 cases show the three essential features that characterize SIDS: over-representation of males, increased deaths during the second and third months of life, and increased deaths during winter. The autopsy examination revealed that many of these deaths had a medical explanation. Almost half were assigned to group 1. At the time of autopsy, no precise pathology could be diagnosed for 147 deaths; of these, 140 showed histological anomalies. There were only seven sudden deaths for which no abnormal sign was evident at the autopsy. These results are compared with those of similar studies and discussed in connection with three factors: the initial selection of cases, the nature and degree of the investigations, and the possible interpretations of the symptoms uncovered.     

Sudden unexpected child deaths: forensic autopsy results in cases of sudden deaths during a 5-year period

The aim of the present study was to determine the incidence of various causes of sudden unexpected child deaths (SUCD) and to assess the importance of an autopsy in predicting the likelihood of finding a cause of death. A retrospective analysis of autopsy findings in 97 cases of SUCD between the ages of 0--11 years was undertaken at the Council of Forensic Medicine, Ankara during a 5-year period (1995--2000). Cases were classified as explained causes (80.42 per cent) and sudden infant death syndrome (SIDS) (19.58 per cent). A total of 25.77 per cent of the deaths occurred in the neonatal period, 45.31 per cent of them in the first year of life and the remaining 28.86 per cent after 1 year of life. The causes of neonatal deaths were respiratory pathology (five cases), birth complications (four cases), gastrointestinal pathology (one case), homicide (10 cases), and SIDS (five cases). The incidence of SIDS in the newborn period was 33 per cent. The incidence of unexplained causes of deaths in the postneonatal period was 31 per cent and the causes of deaths were respiratory pathology (15 cases), aspiration (five cases), gastrointestinal pathology (four cases), SIDS (14 cases), and other causes (four cases). The study of an entire population provides more reliable data regarding causes of sudden unexpected child deaths than does the study of small groups and it is also recommended that in addition to a through evaluation, a detailed autopsy must be performed for each case in experienced centers.     

Risk factors of sudden infant death and of death by accidents. According to a national survey in the total postneonatal death]

BACKGROUND. The incidence of sudden infant death syndrome (SIDS) peaks at 2-4 month of age and during the colder months of the year. Other risk factors such as sex, birth weight, maternal age and multiple pregnancy also seem to be shared by the other causes of death after the neonatal period. POPULATION AND METHODS. A retrospective, exhaustive survey of all deaths of infants aged 28 days-one year was carried out between September 1986 to December 1987. The control group was a representative sample of the live births in France during 1989. The deaths were classified into 3 groups: group I, 1184 SIDS, group II 228 SIDS remaining unexplained after autopsy (out of 315 autopsied SIDS), and group III 83 accidental deaths. The factors studied were: sex, birth weight, maternal age, number of infants born from the pregnancy. The risk factors were measured by Odds Ratios and the variables related to mortality were introduced into a logistic model. RESULTS. Incidence of deaths peaked between the 2nd and the 4th month of age in groups I and II while deaths were evenly distributed throughout the first year in group III. Colder months, male gender, low birthweight, multiple birth and the young age of the mother all increased the risk of death in SIDS (groups I and II) but the same factors were also linked to accidental deaths. CONCLUSION. The results confirm those of earlier reports and raise the question why the risk factors for accidental deaths are similar to those for explained or unexplained SIDS, except for infant age.     

Are risk factors for sudden infant death syndrome different at night?

AIMS: To determine whether the risk factors for SIDS occurring at night were different from those occurring during the day. METHODS: Large, nationwide case-control study, with data for 369 cases and 1558 controls in New Zealand. RESULTS: Two thirds of SIDS deaths occurred at night (between 10 pm and 7 30 am). The odds ratio (95% CI) for prone sleep position was 3.86 (2.67 to 5.59) for deaths occurring at night and 7.25 (4.52 to 11.63) for deaths occurring during the day; the difference was significant. The odds ratio for maternal smoking for deaths occurring at night was 2.28 (1.52 to 3.42) and that for the day 1.27 (0.79 to 2.03); that for the mother being single was 2.69 (1.29 to 3.99) for a night time death and 1.25 (0.76 to 2.04) for a daytime death. Both interactions were significant. The interactions between time of death and bed sharing, not sleeping in a cot or bassinet, Maori ethnicity, late timing of antenatal care, binge drinking, cannabis use, and illness in the baby were also significant, or almost so. All were more strongly associated with SIDS occurring at night. CONCLUSIONS: Prone sleep position was more strongly associated with SIDS occurring during the day, whereas night time deaths were more strongly associated with maternal smoking and measures of social deprivation.     

Sudden infant death syndrome among twins.

BACKGROUND: Sudden infant death syndrome (SIDS) is a major contributor to infant mortality. Previous studies have suggested that infants born of twin pregnancies are at greater risk for SIDS and that a twin who survives after a co-twin dies is at increased risk for SIDS. OBJECTIVE: To attempt to confirm the increased risk of SIDS among and within twin pairs through the use of US vital statistics data. METHODS: We analyzed data from the US-linked birth and infant death certificate tapes for the years 1987 through 1991 to determine the risk of SIDS in twin births compared with singleton births and to describe the characteristics of twin pairs in whom SIDS occurred. The analysis was limited to live births with weights of 500 g or more and gestational ages of 24 weeks or more. We used an algorithm to match co-twins (infants within a twin pair) to measure sex and birth weight concordancy, to identify twin pairs, in which one or both twins died of SIDS; and to examine, when both twins died, whether they died on the same day. RESULTS: There were 23464 singleton SIDS deaths and 1056 twin SIDS deaths during the 5-year period. The crude relative risk for SIDS among twins compared with singleton births was 2.06 (95% confidence interval, 1.94-2.19). The adjusted relative risk independent of birth weight and sociodemographic variables was 1.13 (95% confidence interval, 0.97-1.31). We successfully matched the co-twins of 172029 twin pregnancies. Of these, 767 were twin pregnancies in which one or both twins died of SIDS. Among the 767 twin pregnancies in which one or both twins experienced SIDS, there were only 7 in which both twins died of SIDS (rate ratio, 4.0 per 100000 twin pregnancies). In only 1 of these 7 did both twins die on the same day (rate ratio, 0.58 per 100000 twin pregnancies). The relative risk for a second twin dying of SIDS was 8.17 (90% confidence interval, 1.18-56.67). CONCLUSIONS: Independent of birth weight, twins do not appear to be at greater risk for SIDS compared with singleton births. In addition, the occurrence of both twins dying of SIDS is uncommon, and the occurrence of both twins dying on the same day is extremely uncommon.     

Sudden infant death syndrome in infants born to HIV-infected and opiate-using mothers.

OBJECTIVE: This study was undertaken to determine the role of opiate use during pregnancy as a predisposing factor for sudden infant death syndrome (SIDS) in infants born to HIV-infected mothers. METHODS: In order to identify all infant deaths and their cause and association with maternal opiate use, the data of a nationwide prospective cohort study of HIV-infected mothers and their children were extracted and analysed for a 13-year period. RESULTS: 24 (5.1%) infant deaths were observed out of 466 infants followed up until death or at least 12 months of life. 3 (0.6%) of them were due to non-accidental trauma and were not associated with maternal opiate use. 7 (1.5%) died due to SIDS, which was confirmed by autopsy. All SIDS cases occurred in infants born to mothers reporting use of opiates during pregnancy (n = 124). The relative risk of SIDS compared to the general population was 18 (95% CI 9 to 38) for all infants of HIV-infected mothers, and 69 (95% CI 33 to 141) for those with intrauterine opiate exposure (p<0.001). CONCLUSIONS: Compared to the Swiss general population, the risk for SIDS in this cohort of infants born to HIV-infected mothers was greatly increased, but only for mothers reporting opiate use during pregnancy. This effect appeared not to be mediated by prematurity, low birth weight, perinatal HIV infection or antiretroviral drug exposure.     

Considering suffocatory abuse and Munchausen by proxy in the evaluation of children experiencing apparent life-threatening events and sudden infant death syndrome

This study describes 138 young children admitted to the hospital over a 23 year period for recurrent apparent life threatening events (ALTEs), unexplained deaths, or with Sudden Infant Death Syndrome (SIDS)-related diagnoses. In examining the potential for suffocatory abuse in living children, we utilized characteristics in the literature that distinguish SIDS or ALTEs due to natural disease states from abuse. Findings demonstrate a co-occurrence of risk factors that raise suspicions of suffocatory abuse or Munchausen by Proxy. Of the 35 children who died, SIDS was the presumed clinical diagnosis at the time of death in 71 % of the cases. Comprehensive chart review and autopsy findings revealed a non-SIDS diagnosis in 54% and confirmed or suspicious child abuse in 37% of these deaths. Reports to Child Protective Services were made in 6% of cases. Recommendations for assessment of children including attention to risk indicators, involvement of child protection teams, mandatory autopsies, and eath scene investigations are offered.     

Gastric aspiration and sleeping position in infancy and early childhood

Concern has been expressed that the recommendation of supine sleeping position for infants would result in an increase in deaths due to gastric aspiration. A review of 196 cases of infant and early childhood death in children under 3 years of age, occurring over a 9-year period (September 1989 to August 1998) was undertaken to ascertain how many cases of significant gastric aspiration had occurred. Extensive and widespread filling of the airways/alveoli with gastric contents was found in three infants/young children aged 5, 6 and 30 months, respectively. In each instance the body had been found lying face down (prone), with the face in a pool of vomitus in at least one case. No cases of significant gastric aspiration were found in infants who had been found lying on their sides or backs (supine). In addition, no significant increase in numbers of infant and early childhood deaths in South Australia due to gastric aspiration over this time could be demonstrated. Concerns that the supine rather than the prone position is more likely to result in significant gastric aspiration are not supported by this study.     

Maternal smoking: an increasing unique risk factor for sudden infant death syndrome in Sweden

Aim: To assess the change of risk factors that are specific to sudden infant death syndrome (SIDS) after the initialization of a campaign to reduce the risk (RTR) of SIDS compared to non-SIDS postneonatal deaths. Methods: Data were extracted from the Swedish Medical Birth Registry, 1982-1991 and 1993-1998. 1105 infants died from SIDS during the postneonatal period, 2115 postneonatal deaths were from other causes and 11 050 live birth controls were selected. Risk factors previously identified to be related to SIDS were defined as high parity, prematurity, young maternal age, low Apgar score, birth during the night, single motherhood, multiple births, maternal smoking, male gender, short length standard deviation score (SDS) and small weight-to-length SDS. Results: Non-SIDS deaths were more significantly related to a low 5-min Apgar score, smaller weight-to-length SDS, and/or short length SDS values; while SIDS deaths were more closely related to mothers with higher parity or multiple births, mothers who smoked during pregnancy and single-parent (mother) families. Maternal smoking was even more prominent among SIDS deaths in the post-campaign period. The adjusted odds ratios, compared with non-SIDS deaths, increased from 1.84 (95% CI: 1.48, 2.28) in the pre-campaign period to 4.11 (95% CI: 2.72, 6.21) in the post-campaign period.

Conclusions: Maternal smoking during pregnancy remains the most important modifiable risk factor for SIDS in the post-campaign period in comparison with non-SIDS postneonatal deaths. Other than putting babies in a supine sleeping position, maternal smoking should be the next most important issue to be considered, if there is to be a second campaign.     

Investigation of unexplained infant deaths in Jerusalem, Israel 1996-2003.

BACKGROUND: Sudden infant death syndrome (SIDS) is a diagnosis of exclusion that may be assigned only after investigations including a forensic autopsy are performed to exclude possible organic and environmental causes of death. Israeli society is influenced by the Jewish and Islamic faiths, which permit autopsy only under selected circumstances. Against this background, we carried out a study to determine what examinations are performed to investigate unexplained infant deaths in Jerusalem, Israel. METHODS: We examined hospital, Ministry of Health and Ministry of Interior records of unexplained infant deaths in the Jerusalem district from the years 1996-2003. RESULTS: Ninety six cases were identified from all sources. Forty nine (51%) infants were brought to a hospital at or near the time of death. Studies to determine the cause of death were performed in 54% of cases for which medical records were available for review. These studies included bacterial cultures (44%), skeletal surveys (12%), computerised tomography (3%) and metabolic studies (3%). Only one forensic autopsy was performed, and in no instance was the death site examined by medical personnel. There was a high rate of retrospective review by district health physicians. The most frequently assigned cause of death was SIDS. CONCLUSIONS: : The capacity of public health officials and forensic pathologists to investigate unexplained infant deaths is strongly affected by the legal, religious and political milieu in which they work. Efforts should be made to develop socially acceptable methods of improving the quality of infant death investigations in Jerusalem.     

Helicobacter pylori antigen in stool is associated with SIDS and sudden infant deaths due to infectious disease

Infection with Helicobacter pylori has been proposed to be a common cause of Sudden Infant Death Syndrome (SIDS). We investigated the frequency of H. pylori infection in 160 infant deaths and 156 live controls by means of the Helicobacter pylori stool antigen (HpSA) immunoassay. Histology was performed in 26 randomly selected cases. H. pylori antigen was detected in 8% (12/156) of the live controls compared with 25% (30/122) of SIDS cases (p < 0.001), 53% (9/17) of deaths due to infection (p < 0.001), and 9% (1/11) of accidental/violent deaths (p = 0.60). In the classic age peak for SIDS, 1-5 mo, 31% (21/67) of SIDS cases were HpSA positive compared with 1.5% (1/68) of live controls (p < 0.001). Rod-like immunoperoxidase positive H. pylori organisms were identified in 7/12 HpSA positive gastric antrum sections compared with 2/14 HpSA negative (p = 0.038). Significantly elevated IL-6 levels in cerebrospinal fluid representing signs of central immune stimulation were demonstrated in HpSA positive SIDS victims compared with HpSA negative victims (p = 0.045). Detection of H. pylori antigen in stool is associated with SIDS and deaths due to infections. We hypothesize that H. pylori infection in infancy may be involved as the triggering pathogen for sudden death during the first 5 month after birth.     

Vitreous humor hypoxanthine levels in SIDS and infectious death

Vege Å, Chen Y, Opdal SH, Saugstad OD, Rognum TO. Vitreous humor hypoxanthine levels in SIDS and infectious death. Acta Pæediatr 1994;83:634–9. Stockholm. ISSN 0803–5253
Hypoxanthine concentrations in vitreous humor were determined in 107 cases of sudden infant death syndrome (SIDS) and compared with levels in 4 cases of borderline SIDS, 26 cases of infectious death and 16 cases of sudden violent death. The hypoxanthine measurements were made using a high-pcrformance liquid chromatography method. The hypoxanthine levels were significantly (p<0.01) higher in SIDS than in violent deaths, while no significant difference was found between SIDS and infectious deaths. The present report demonstrates a similar distribution pattern of hypoxanthine levels in vitreous humor in SIDS and infectious death. We have previously described signs of immune stimulation both in peripheral organs and in the central nervous system in these conditions. This indicates that the death mechanism in SIDS has some similarities with infectious death.     

Sudden infant death syndrome and sleeping position in pre-term and low birth weight infants: an opportunity for targeted intervention.

AIMS: To determine the combined effects of sudden infant death syndrome (SIDS) risk factors in the sleeping environment for infants who were "small at birth" (pre-term (<37 weeks), low birth weight (<2500 g), or both). METHODS: A three year population based, case-control study in five former health regions in England (population 17.7 million) with 325 cases and 1300 controls. Parental interviews were carried out after each death and reference sleep of age matched controls. RESULTS: Of the SIDS infants, 26% were "small at birth" compared to 8% of the controls. The most common sleeping position was supine, for both controls (69%) and those SIDS infants (48%) born at term or > or =2500 g, but for "small at birth" SIDS infants the commonest sleeping position was side (48%). The combined effect of the risk associated with being "small at birth" and factors in the infant sleeping environment remained multiplicative despite controlling for possible confounding in the multivariate model. This effect was more than multiplicative for those infants placed to sleep on their side or who shared the bed with parents who habitually smoked, while for those "small at birth" SIDS who slept in a room separate from the parents, the large combined effect showed evidence of a significant interaction. No excess risk was identified from bed sharing with non-smoking parents for infants born at term or birth weight > or =2500 g. CONCLUSION: The combined effects of SIDS risk factors in the sleeping environment and being pre-term or low birth weight generate high risks for these infants. Their longer postnatal stay allows an opportunity to target parents and staff with risk reduction messages.     

Formal retrospective case review and sudden infant death

A review of 24 consecutive sudden infant deaths was undertaken to evaluate the importance of the various stages in the postmortem assessment of such cases. Death in three cases was caused by obvious trauma. Of the remainder, 16 were attributed to sudden infant death syndrome (SIDS), 4 to accidental asphyxia (identified by death scene examination and/or formal case review) and 1 to a lingual thyroglossal duct cyst. Three (14%) of 21 deaths thought to be SIDS after postmortem examination were attributed to asphyxia following subsequent formal case review.     

The seasonal distribution of infant deaths by age: A comparison of sudden infant death syndrome and other causes of death

Objective: To examine the possibility that among deaths in infancy the increase in the winter/summer ratio with increasing age is not peculiar to sudden infant death syndrome (SIDS).
Methodology: Details of the winter (December-February)/summer (June-August) ratio among deaths in neonates (<28 days) and post neonates dying in the United States of America between 1979 and 1990 were abstracted from published statistics. The primary causes of death were classified according to the ninth Revision of the International Classification of Diseases.
Results: For every non-traumatic cause of death including SIDS, the winter/summer ratio was higher among postneonates than neonates. This was not seen for deaths due to trauma. Cases of SIDS and deaths due to infection had the highest ratios in both age categories. Causes of death occurring predominantly in the neonatal period (e.g. anencephaly) had the lowest overall ratios.
Conclusions: Neither the greater number of SIDS cases in the winter, nor the increasing winter/summer ratio with increasing age is unique to SIDS.     

Has changing diagnostic preference been responsible for the recent fall in incidence of sudden infant death syndrome in South Australia?

Objective: An apparent decrease in deaths attributed to sudden infant death syndrome (SIDS) has been noted in a number of diverse geographical areas during the past several years. At the same time the definition of SIDS has been in a state of flux and some observers have raised the possibility that the fall in SIDS deaths is due to diagnostic transfer rather than to a genuine decrease in numbers. The present study was undertaken to investigate this possibility.
Methodology: All sudden and unexpected deaths in infants under 1 year of age in South Australia during a 10 year period from 1984 to 1993 were reviewed.
Results: The number of deaths due to SIDS fell from 40 in 1984 to 17 in 1993, with a maximum of 52 cases per year in 1987. In contrast, the number of cases of sudden death not due to SIDS remained under 10 per year. The overall infant death rate also fell, while the total number of births per year remained relatively unchanged.
Conclusions: The lack of major change in sudden infant death rates from other causes, combined with the fall in SIDS deaths, is not supportive of diagnostic transfer being a major determinant of the declining SIDS death rate. Therefore, other factors are likely to be responsible for the falling SIDS rate in this population.     

Changes in the epidemiologic profile of sudden infant death syndrome as rates decline among California infants: 1990-1995

OBJECTIVES: To evaluate changes in the rates and epidemiologic patterns of sudden infant death syndrome (SIDS) after implementation of public health campaigns to promote back sleeping and reduce exposure to cigarette smoke and environmental risk factors for SIDS. METHODS: California vital statistics data were used to evaluate changes in SIDS rates (deaths/1000 live births) and in the proportions of SIDS deaths by age and season of occurrence for California infants of black or other races from 1990 through 1995. RESULTS: From 1990 through 1995, 3508 SIDS deaths occurred. SIDS rates declined from 2.69 to 2.15 for black infants and from 1.04 to 0.61 for others between 1990 and 1995. Most SIDS deaths occurred during the 2nd to 4th months of life; the proportion of SIDS deaths during this period was unchanged for blacks but decreased for others from 70% to 65%. Of all SIDS deaths, 62% occurred during the colder season (October through March); the proportion of deaths in each season did not change for either race. CONCLUSION: California SIDS rates declined 20% for blacks and 41% for others between 1990 and 1995. Declines coincided with campaigns to reduce environmental risk factors for SIDS. Blacks continue to be at increased risk for SIDS compared with others, and the SIDS rate for blacks relative to others has increased. Reductions in SIDS mortality coinciding with interventions were smaller for blacks than for others. New strategies are needed to reduce further SIDS rates and narrow the gap between blacks and others.     

Sudden infant death syndrome in infants evaluated by apnea programs in California

Home apnea/bradycardia monitoring is frequently used in the management of infants at increased risk for sudden infant death syndrome (SIDS). However, some infants have died despite evaluation by infant apnea programs, and the benefits of home monitoring remain unproven. To determine the SIDS rate and risk factors of infants evaluated by infant apnea programs, 31 apnea programs and ten home monitor vendors in California were surveyed. Eleven (35%) of the apnea programs and four (40%) of the vendors responded. Information was obtained on 26 infants who died. Thirteen (50%) deaths were due to SIDS. Abnormal sleep studies did not predict death. Fifteen infants died despite a recommendation for home monitoring. Seven deaths occurred in association with technical errors or noncompliance with monitoring. Four deaths were due to nonaccidental trauma. The apnea programs evaluated 3,406 infants during a 5-year period; 1,841 had monitoring recommended. Term infants with apnea, subsequent siblings of SIDS victims, and infants evaluated at referral centers were more likely to have monitoring recommended than premature infants with apnea or infants evaluated at nonreferral centers (P less than .0001). Infants who had monitoring recommended were at equal risk of dying of SIDS as those who did not.