Inconsistent classification of unexplained sudden deaths in infants and children hinders surveillance, prevention and research: recommendations from The 3rd International Congress on Sudden Infant and Child Death

Known pathogenic gene variants and new candidates detected in sudden unexpected infant death using whole genome sequencing

The purpose of this study is to gain insights into potential genetic factors contributing to the infant's vulnerability to Sudden Unexpected Infant Death (SUID). Whole Genome Sequencing (WGS) was performed on 144 infants that succumbed to SUID, and 573 healthy adults. Variants were filtered by gnomAD allele frequencies and predictions of functional consequences. Variants of interest were identified in 88 genes, in 64.6% of our cohort. Seventy-three of these have been previously associated with SIDS/SUID/SUDP. Forty-three can be characterized as cardiac genes and are related to cardiomyopathies, arrhythmias, and other conditions. Variants in 22 genes were associated with neurologic functions. Variants were also found in 13 genes reported to be pathogenic for various systemic disorders and in two genes associated with immunological function. Variants in eight genes are implicated in the response to hypoxia and the regulation of reactive oxygen species (ROS) and have not been previously described in SIDS/SUID/SUDP. Seventy-two infants met the triple risk hypothesis criteria. Our study confirms and further expands the list of genetic variants associated with SUID. The abundance of genes associated with heart disease and the discovery of variants associated with the redox metabolism have important mechanistic implications for the pathophysiology of SUID.

The French registry of sudden unexpected death in infancy (SUDI): a 7-year review of available data

The French "OMIN registry" was established in 2015 to collect nationwide standardised data concerning biological, clinical, environmental and social characteristics of sudden unexpected death in infancy (SUDI) and unexpected death in children aged 1-2 years. A biobank has existed since July 2020 to store biological samples for each case. This article aimed to detail (1) a brief history and the objectives of the registry; (2) a description of the methodology used; (3) the first results of the registry, i.e. the main characteristics of the cases included so far; (4) the process for accessing the data for research projects; and (5) issues regarding weakness and improvement and perspectives offered by the registry. On 31 May 2024, 1975 cases were included in the OMIN registry; on 31 December 2022, 4606 biological samples from 176 cases were collected. For each deceased child, different types of data are registered on an electronic case report form: socio-demographic data, personal and familial medical background, environment and feeding data, clinical data, and biological and imaging results. A strict and continuous quality control process is used to ensure the reliability of the data, in parallel with specific actions to improve the exhaustiveness of the registry. The OMIN registry database is one of the largest and the most complete databases on SUDI, especially in Europe, and the first in the world to associate a standardised biological sample collection with it. Perspectives of research provided by our registry are numerous and could be supported by national and international scientific collaborations.

CONCLUSION

 This article details the objectives and methods of the French registry of SUDI. It provides initial results relating to the population included in the register and the procedure for accessing the data.

WHAT IS KNOWN

• In Western Europe, France is one of the countries with the highest SUDI rate, making it the first cause of death of infants between 28 and 364 days. • The development of epidemiological tools on a national and international scale is essential to advance research into the determinants and risk factors of unexpected death in children under 2 years of age.

WHAT IS NEW

• The OMIN registry was created in France in 2015 to collect nationwide standardised social, environmental, clinical, and paraclinical data for cases of unexpected death in children aged 0 to 2 years. • To date, the OMIN registry has included 680 data from almost 2000 children unexpectedly deceased, completed by a biocollection since 2020. • Data from the OMIN registry, unique in its field, are freely available for scientific research teams, after acceptation by the scientific committee of the registry.

National SIDS Trends in the United States From 2000 to 2019: A Population-Based Study on 80 Million Live Births

Sudden infant death syndrome (SIDS) is the most common cause of death for infants between 1 month and 1 year of age in the United States. The objective was to examine recent trends in SIDS in the United States, over time and by sex and race. A population-based cross-sectional study was conducted on 80 710 348 live births using data from the Center for Disease Control and Prevention's (CDC) "Birth Data" and "Mortality Multiple Cause" files from 2000 to 2019. Logistic regression examined the effects of sex and race on the risk of SIDS and examined temporal changes in risk across sex and race over the study period. Incidence of SIDS decreased from 6.3 to 3.4/10 000 births from 2000 to 2019, with an overall incidence of 4.9/10 000 births (95% confidence interval [CI] = 4.4-5.3). Male infants were at the greatest risk of SIDS as were black and American Indian infants. Although SIDS incidence decreased by sex and race over time, the decline was smaller among Hispanic and American Indian infants.

Added value of postmortem mri in sudden unexpected infant death cases

We aimed to investigate the potential added value of postmortem MRI (PMMRI) in sudden unexpected infant death (SUID) cases referred to our center between September 2020 and June 2023. Ultimately, 19 SUID cases underwent PMMRI alongside standard autopsy procedures, which included technical examinations such as postmortem CT (PMCT). Four radiologists, two with prior PMMRI experience, provided structured reports following consensus. For each case, the responsible forensic medicine specialist documented the cause of death before and after reviewing the PMMRI report. Additionally, they assessed the overall impact of the PMMRI report and had the opportunity to provide written comments. The results of our study indicate that none of the PMMRI reports altered the prior determined cause of death, which included cases of infection, asphyxia, and sudden infant death syndrome (SIDS). However, we observed a moderate impact in one case and a low impact in 10 cases. The moderate impact arose from the PMMRI report identifying hypoxic-ischemic changes, where histologic examination of the brain was perceived as normal. Conversely, in the 10 cases with a low impact, the PMMRI reports supported the autopsy findings, specifically indicating brain injury and intra-alveolar cellular infiltrates. In conclusion, our study suggests that while PMMRI may not be pivotal in determining the cause of death in SUID cases, it could aid in detecting hypoxic-ischemic changes and reinforcing brain and lung observations. However, distinguishing genuine lung pathology from postmortem changes using PMMRI remains challenging. Further research is warranted to clarify the role of PMMRI in forensic SUID investigations.

Dysregulation of platelet serotonin, 14-3-3, and GPIX in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the leading cause of post-neonatal infant mortality, but the underlying cause(s) are unclear. A subset of SIDS infants has abnormalities in the neurotransmitter, serotonin (5-hydroxytryptamine [5-HT]) and the adaptor molecule, 14-3-3 pathways in regions of the brain involved in gasping, response to hypoxia, and arousal. To evaluate our hypothesis that SIDS is, at least in part, a multi-organ dysregulation of 5-HT, we examined whether blood platelets, which have 5-HT and 14-3-3 signaling pathways similar to brain neurons, are abnormal in SIDS. We also studied platelet surface glycoprotein IX (GPIX), a cell adhesion receptor which is physically linked to 14-3-3. In infants dying of SIDS compared to infants dying of known causes, we found significantly higher intra-platelet 5-HT and 14-3-3 and lower platelet surface GPIX. Serum and plasma 5-HT were also elevated in SIDS compared to controls. The presence in SIDS of both platelet and brainstem 5-HT and 14-3-3 abnormalities suggests a global dysregulation of these pathways and the potential for platelets to be used as a model system to study 5-HT and 14-3-3 interactions in SIDS. Platelet and serum biomarkers may aid in the forensic determination of SIDS and have the potential to be predictive of SIDS risk in living infants.

Multiomic Analysis of Neuroinflammation and Occult Infection in Sudden Infant Death Syndrome

Importance

Antemortem infection is a risk factor for sudden infant death syndrome (SIDS)-the leading postneonatal cause of infant mortality in the developed world. Manifestations of infection and inflammation are not always apparent in clinical settings or by standard autopsy; thus, enhanced resolution approaches are needed.

Objective

To ascertain whether a subset of SIDS cases is associated with neuroinflammation and occult infection.

Design, Setting, and Participants

In this case-control study, postmortem fluids from SIDS cases and controls collected between July 2011 and November 2018 were screened for elevated inflammatory markers, specifically cerebrospinal fluid (CSF) neopterin and CSF and serum cytokines. CSF, liver, and brain tissue from SIDS cases with elevated CSF neopterin were subjected to metagenomic next-generation sequencing (mNGS) to probe for infectious pathogens. Brainstem tissue from a subset of these cases was analyzed by single-nucleus RNA sequencing (snRNAseq) to measure cell type-specific gene expression associated with neuroinflammation and infection. All tissue and fluid analyses were performed from April 2019 to January 2023 in a pathology research laboratory. Included was autopsy material from infants dying of SIDS and age-matched controls dying of known causes.

Exposures

There were no interventions or exposures.

Main Outcomes and Measures

CSF neopterin levels were measured by high-performance liquid chromatography. Cytokines were measured by multiplex fluorometric assay. mNGS was performed on liver, CSF, brain, and brainstem tissue. snRNAseq was performed on brainstem tissue.

Results

A cohort of 71 SIDS cases (mean [SD] age, 55.2 [11.4] postconceptional weeks; 42 male [59.2%]) and 20 controls (mean [SD] age, 63.2 [16.9] postconceptional weeks; 11 male [55.0%]) had CSF and/or serum available. CSF neopterin was screened in 64 SIDS cases and 15 controls, with no exclusions. Tissues from 6 SIDS cases were further analyzed. For CSF neopterin measures, SIDS samples were from infants with mean (SD) age of 54.5 (11.3) postconceptional weeks (38 male [59.4%]) and control samples were from infants with mean (SD) age of 61.5 (17.4) postconceptional weeks (7 male [46.7%]). A total of 6 SIDS cases (9.3%) with high CSF neopterin were identified, suggestive of neuroinflammation. mNGS detected human parechovirus 3 (HPeV3) in tissue and CSF from 1 of these 6 cases. snRNAseq of HPeV3-positive brainstem tissue (medulla) revealed dramatic enrichment of transcripts for genes with predominately inflammatory functions compared with 3 age-matched SIDS cases with normal CSF neopterin levels.

Conclusions and Relevance

Next-generation molecular tools in autopsy tissue provide novel insight into pathogens that go unrecognized by normal autopsy methodology, including in infants dying suddenly and unexpectedly.

Altered 5-HT2A/C receptor binding in the medulla oblongata in the sudden infant death syndrome (SIDS): Part II. Age-associated alterations in serotonin receptor binding profiles within medullary nuclei supporting cardiorespiratory homeostasis

The failure of chemoreflexes, arousal, and/or autoresuscitation to asphyxia may underlie some sudden infant death syndrome (SIDS) cases. In Part I, we showed that some SIDS infants had altered 5-hydroxytryptamine (5-HT)2A/C receptor binding in medullary nuclei supporting chemoreflexes, arousal, and autoresuscitation. Here, using the same dataset, we tested the hypotheses that the prevalence of low 5-HT1A and/or 5-HT2A/C receptor binding (defined as levels below the 95% confidence interval of controls-a new approach), and the percentages of nuclei affected are greater in SIDS versus controls, and that the distribution of low binding varied with age of death. The prevalence and percentage of nuclei with low 5-HT1A and 5-HT2A/C binding in SIDS were twice that of controls. The percentage of nuclei with low 5-HT2A/C binding was greater in older SIDS infants. In >80% of older SIDS infants, low 5-HT2A/C binding characterized the hypoglossal nucleus, vagal dorsal nucleus, nucleus of solitary tract, and nuclei of the olivocerebellar subnetwork (important for blood pressure regulation). Together, our findings from SIDS infants and from animal models of serotonergic dysfunction suggest that some SIDS cases represent a serotonopathy. We present new hypotheses, yet to be tested, about how defects within serotonergic subnetworks may lead to SIDS.

Infant death from accidental suffocation and strangulation in bed in England and Wales: rare or unrecognised events?

BACKGROUND

Mandatory joint police and healthcare investigations of sudden unexpected death in infancy (SUDI) have been in place since 2008 in England. These include death scene examination with cause of death determined at multiprofessional case conference. Detailed evidence on sleep arrangements is available for most cases potentially leading to more being identified as due to accidental suffocation. SUDI remaining unexplained following investigation are classified as SIDS (sudden infant death syndrome) or unspecified deaths.Our objective was to determine whether detailed SUDI investigation has led to an increase in deaths classified as accidental suffocation or strangulation in bed (ASSB)?

METHODS

We obtained official mortality data for England and Wales for infants dying aged 0-364 days for International Statistical Classification of Diseases and Related Health Problems, 10th revision codes R95 (SIDS), R96, R98, R99 (unspecified causes of mortality) and W75 (ASSB) for the years 2000-2019.We calculated the mortality rate for ASSB, SIDS and unspecified causes based on total live births each year.

RESULTS

Unexplained SUDI decreased from 353 in 2000 to 175 in 2019, with the mortality rate falling from 0.58 to 0.29 per 1000 live births. The total postneonatal mortality rate fell during this time from 1.9 to 0.9 per 1000 live births suggesting this is a genuine fall. SIDS accounted for 70% of unexplained SUDI in 2000 falling to 49% in 2020 with a corresponding increase in R99 unspecified deaths.Few deaths were recorded as ASSB (W75), ranging between 4 in 2010 and 24 in 2001. The rate for ASSB ranged from 0.6 to 4.0 per 100000 live births.

CONCLUSIONS

There is a shift away from SIDS (R95) towards unspecified causes of death (R96, R98, R99). Improved investigation of deaths has not led to increased numbers of death identified as due to ASSB. There needs to be clear guidelines on accurate classification of deaths from ASSB to facilitate learning from deaths and inform prevention efforts.

Pathological causes of sudden death in autopsied children with reference to peculiar findings: An Egyptian perspective

Childhood is a long period extending up to the age of 18 years. Childhood encompasses different developmental stages; each stage has specific characteristics. This 5-year study included 244 autopsied children who died unexpectedly due to natural causes. This study was conducted in the forensic pathology unit of the Egyptian Forensic Medicine Authority (EFMA). Pathological causes of death were diagnosed in 181 cases, representing nearly three-quarters (74.2 %) of cases. Males represented 60.8 % of these cases. More than half (51.4 %) of deaths due to natural disease occurred within the first month of life. The diagnosis was established for the first-time during autopsy in 58 % of cases. Prematurity complications and infections were the cause of death in 35.9 % and 30.4 % of deaths attributed to natural pathologies, respectively. Prematurity complications are the most common cause of death in perinatal (63.6) and neonatal (71.4 %) periods. Whereas infection is the most common cause of death during infancy (55 %), childhood (52.8 %), and adolescence (43.8 %). Pneumonia was the most common infection (61.8 %). This study highlighted cases with peculiar pathologies that include cardiomyopathies (idiopathic dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), and Arrhythmogenic right ventricular cardiomyopathy (ARVD)), Waterhouse-Friderichsen syndrome (WFS), ruptured cerebral cavernous hemangioma, and cerebellar medulloblastoma.

Aberrant colon metabolome and the sudden infant death syndrome

BACKGROUND

The Sudden Infant Death Syndrome (SIDS) has been associated with increased peripheral serotonin and an abnormal colonic microbiome, suggesting the colonic metabolome may also be abnormal. This study addresses this potential correlation by comparing colonic autopsy tissue from SIDS to age-matched non-SIDS controls.

METHODS

Untargeted metabolomic analysis by mass spectrometry is used to assess human colonic metabolomic differences including serotonin. Expression of genes associated with colonic serotonin synthesis and transport (TPH1, TPH2, DDC, SCL6A4) is measured by qRT-PCR. Microbiome analysis is performed to compare the SIDS and non-SIDS colonic microbiome.

RESULTS

Unsupervised hierarchical cluster and principal component analyses of metabolomic data shows increased variability in the SIDS cohort and separation of SIDS cases from the non-SIDS controls. There is a trend toward increased serotonin in the SIDS cohort but there is no significant difference in expression of the serotonin synthesis and transport genes between SIDS and non-SIDS control cohorts. Microbiome analysis shows no significant difference between the SIDS and non-SIDS control cohorts.

CONCLUSIONS

This study demonstrates increased variability in the colonic metabolome and a trend towards increased colonic serotonin in SIDS. The underlying cause of colon metabolomic variability, and its potential role in SIDS pathogenesis, warrants further investigation.

IMPACT STATEMENT

The key message of this article is that SIDS is associated with an aberrant colonic metabolome. This is a novel observation suggesting another component in the pathophysiology underlying SIDS. Investigation of why the colonic metabolome is aberrant may offer new insights to SIDS pathogenesis and new strategies to reduce risk.

Brain water content in sudden unexpected infant death

The extensive and rapid development of the human brain during the first years of life complicates the postmortem diagnosis of brain edema in infancy. The aim of this study was to describe brain water content, the brain weight/body weight ratio, and the brain weight/head circumference ratio throughout the first years of life. Furthermore, we examined the relationship between these parameters and rs2075575 in the AQP4 gene. Our hypothesis was that dysregulated water homeostasis might be a risk factor for sudden infant death syndrome (SIDS), which may be reflected by increased water content in the brain. The study included 90 subjects with sudden unexpected death < 4 years of age: 22 cases of sudden infant death syndrome, 11 cases of sudden unexplained death in childhood, 47 cases of death due to disease, and 10 cases of accident/violent death. Brain water content, brain weight/body weight ratio, and brain weight/head circumference ratio were investigated according to corrected age, diagnosis group, attempt to resuscitate, and presence of brain edema. We found that brain water content and brain weight/body weight ratio were significantly reduced with increasing age, while brain weight/head circumference were increased. Brain weight/head circumference was correlated with brain water content. Cases with brain edema had a significantly higher brain weight/head circumference than the non-edematous cases. No differences were found between the diagnosis groups for any of the investigated parameters. In summary, the findings contribute to the current body of knowledge regarding brain growth during the first months of life.

Unexplained and Unexpected Pediatric Deaths: Forensic Review and New Perspectives

Unexplained and unexpected pediatric deaths are a major challenge in global healthcare. The role of the forensic pathologist is crucial in determining the cause and manner of death in these cases, although to date, there are many limitations in post-mortem diagnosis. The role of the autopsy and related forensic investigations become a fundamental tool to investigate and give an explanation for an unacceptable event, considering the young age of the victims. From this point of view, even today, it is necessary that this phenomenon is correctly recorded through standardized systems and universally accepted methods. Furthermore, it is essential that scientific research on this topic is increased through the implementation of universally accepted operating protocols recognizing real risk factors in order to prevent such events. The purpose of the study is to offer a review of the state of the art about unexplained pediatric death and, above all, to propose an international reporting platform, extending proper investigations not only to judicial cases but also to all the other cases of unexpected pediatric death.

#sleepingbaby on Instagram: Nonadherence of images to safe sleeping advice and implications for prevention of Sudden Unexpected Death in Infancy

OBJECTIVES

Safe sleep of infants is important to reduce the risk of Sudden Unexpected Death in Infancy (SUDI). The depiction of infant care behavior which is inconsistent with the safe sleep recommendations on social media has an impact on parental infant care thoughts, norms and behaviors. This study aims to determine the adherence of Instagram images to the Dutch safe sleeping advice.

DESIGN

A systematic social media analysis on Instagram was performed using 22 hashtags and 9 accounts of Dutch companies or platforms related to infants. Images of sleeping infants were analyzed on consistency with the criteria: supine sleeping position, own cot or crib, sleep sack, and an empty bed.

RESULTS

Based on 514 collected images, 5.9% was consistent with sleep sack use, 16.8% with an empty bed, 30.7% with an own cot or crib, and 67.5% with the supine sleeping position. For 311 images (60.5%), all four criteria could be rated, as for the others, at least one criterion was not clearly depicted. Only 6 of these images (1.9%) were consistent with all four criteria.

CONCLUSIONS

Although Instagram images are probably not representative of regular infant care behavior, the exposure to these images that are mostly inconsistent with the safe sleep advice can contribute to the formation of norms, and therefore influence parental care behavior. Accurate communication of the safe sleep recommendations through social media is needed, and opportunities are described for preventive health professionals to engage more in this communication with their public.

Case report: Diagnosis of a patient with Sifrim-Hitz-Weiss syndrome, development and epileptic encephalopathy-14, and medium chain acyl-CoA dehydrogenase deficiency

Background

It is generally recognized that genetic metabolic disorders can result in neurological symptoms such as seizures, developmental delay, and intellectual disability. Heterogeneous clinical presentations make the diagnosis challenging.

Case presentation

In this case report, we present a unique and complex genetic disorder observed in a female patient who exhibited three pathogenic gene variants in the KCNT1, ACADM, and CHD4 genes. The convergence of these variants resulted in a multifaceted clinical presentation characterized by severe seizures of combined focal and generalized onset, metabolic dysfunction, and neurodevelopmental abnormalities. The identification and functional characterization of these gene variants shed light on the intricate interplay between these genes and the patient's phenotype. EEG revealed an epileptiform abnormality which presented in the inter-ictal period from the left frontal-central area and in the ictal period from the left mid-temporal area. The brain MRI revealed volume loss in the posterior periventricular area and parietal parenchyma, myelin destruction with no sign of hypoxic involvement, and left dominant enlargement of the lateral ventricles secondary to loss of central parenchyma. The patient was diagnosed through exome sequencing with Sifrim-Hitz-Weiss syndrome, development and epileptic encephalopathy-14, and medium-chain acyl-CoA dehydrogenase deficiency. An antiseizure medication regimen with valproic acid, levetiracetam, phenobarbital, and clonazepam was initiated. However, this led to only partial control of the seizures.

Conclusion

Clinical follow-up of the patient will further define the clinical spectrum of KCNT1, ACADM, and CHD4 gene variants. It will also determine the long-term efficacy of the treatment of seizures and the development of precision medicine for epilepsy syndromes due to gain-of-function variants. Special emphasis should be put on the role and importance of large-scale genomic testing in understanding and diagnosing complex phenotypes and atypical epileptic syndromes.

The fundamental need for unifying phenotypes in sudden unexpected pediatric deaths

A definitive, authoritative approach to evaluate the causes of unexpected, and ultimately unexplained, pediatric deaths remains elusive, relegating final conclusions to diagnoses of exclusion in the vast majority of cases. Research into unexplained pediatric deaths has focused primarily on sudden infant deaths (under 1 year of age) and led to the identification of several potential, albeit incompletely understood, contributory factors: nonspecific pathology findings, associations with sleep position and environment that may not be uniformly relevant, and the elucidation of a role for serotonin that is practically difficult to estimate in any individual case. Any assessment of progress in this field must also acknowledge the failure of current approaches to substantially decrease mortality rates in decades. Furthermore, potential commonalities with pediatric deaths across a broader age spectrum have not been widely considered. Recent epilepsy-related observations and genetic findings, identified post-mortem in both infants and children who died suddenly and unexpectedly, suggest a role for more intense and specific phenotyping efforts as well as an expanded role for genetic and genomic evaluation. We therefore present a new approach to reframe the phenotype in sudden unexplained deaths in the pediatric age range, collapsing many distinctions based on arbitrary factors (such as age) that have previously guided research in this area, and discuss its implications for the future of postmortem investigation.

Altered 5-HT2A/C receptor binding in the medulla oblongata in the sudden infant death syndrome (SIDS): Part I. Tissue-based evidence for serotonin receptor signaling abnormalities in cardiorespiratory- and arousal-related circuits

The sudden infant death syndrome (SIDS), the leading cause of postneonatal infant mortality in the United States, is typically associated with a sleep period. Previously, we showed evidence of serotonergic abnormalities in the medulla (e.g. altered serotonin (5-HT)1A receptor binding), in SIDS cases. In rodents, 5-HT2A/C receptor signaling contributes to arousal and autoresuscitation, protecting brain oxygen status during sleep. Nonetheless, the role of 5-HT2A/C receptors in the pathophysiology of SIDS is unclear. We hypothesize that in SIDS, 5-HT2A/C receptor binding is altered in medullary nuclei that are key for arousal and autoresuscitation. Here, we report altered 5-HT2A/C binding in several key medullary nuclei in SIDS cases (n = 58) compared to controls (n = 12). In some nuclei the reduced 5-HT2A/C and 5-HT1A binding overlapped, suggesting abnormal 5-HT receptor interactions. The data presented here (Part 1) suggest that a subset of SIDS is due in part to abnormal 5-HT2A/C and 5-HT1A signaling across multiple medullary nuclei vital for arousal and autoresuscitation. In Part II to follow, we highlight 8 medullary subnetworks with altered 5-HT receptor binding in SIDS. We propose the existence of an integrative brainstem network that fails to facilitate arousal and/or autoresuscitation in SIDS cases.

Sudden Unexpected Infant Deaths: 2015-2020

OBJECTIVE

Although the US infant mortality rate reached a record low in 2020, the sudden infant death syndrome (SIDS) rate increased from 2019. To understand if the increase was related to changing death certification practices or the coronavirus disease 2019 (COVID-19) pandemic, we examined sudden unexpected infant death (SUID) rates as a group, by cause, and by race and ethnicity.

METHODS

We estimated SUID rates during 2015 to 2020 using US period-linked birth and death data. SUID included SIDS, unknown cause, and accidental suffocation and strangulation in bed. We examined changes in rates from 2019 to 2020 and assessed linear trends during prepandemic (2015-2019) using weighted least squares regression. We also assessed race and ethnicity trends and quantified COVID-19-related SUID.

RESULTS

Although the SIDS rate increased significantly from 2019 to 2020 (P < .001), the overall SUID rate did not (P = .24). The increased SIDS rate followed a declining linear trend in SIDS during 2015 to 2019 (P < .001). Other SUID causes did not change significantly. Our race and ethnicity analysis showed SUID rates increased significantly for non-Hispanic Black infants from 2019 to 2020, widening the disparities between these two groups during 2017 to 2019. In 2020, <10 of the 3328 SUID had a COVID-19 code.

CONCLUSIONS

Diagnositic shifting likely explained the increased SIDS rate in 2020. Why the SUID rate increased for non-Hispanic Black infants is unknown, but warrants continued monitoring. Interventions are needed to address persistent racial and ethnic disparities in SUID.

Copy Number Variation and Structural Genomic Findings in 116 Cases of Sudden Unexplained Death between 1 and 28 Months of Age

In sudden unexplained death in pediatrics (SUDP) the cause of death is unknown despite an autopsy and investigation. The role of copy number variations (CNVs) in SUDP has not been well-studied. Chromosomal microarray (CMA) data are generated for 116 SUDP cases with age at death between 1 and 28 months. CNVs are classified using the American College of Medical Genetics and Genomics guidelines and CNVs in our cohort are compared to an autism spectrum disorder (ASD) cohort, and to a control cohort. Pathogenic CNVs are identified in 5 of 116 cases (4.3%). Variants of uncertain significance (VUS) favoring pathogenic CNVs are identified in 9 cases (7.8%). Several CNVs are associated with neurodevelopmental phenotypes including seizures, ASD, developmental delay, and schizophrenia. The structural variant 47,XXY is identified in two cases (2/69 boys, 2.9%) not previously diagnosed with Klinefelter syndrome. Pathogenicity scores for deletions are significantly elevated in the SUDP cohort versus controls (p = 0.007) and are not significantly different from the ASD cohort. The finding of pathogenic or VUS favoring pathogenic CNVs, or structural variants, in 12.1% of cases, combined with the observation of higher pathogenicity scores for deletions in SUDP versus controls, suggests that CMA should be included in the genetic evaluation of SUDP.

The psychological consequences of Sudden Infant Death Syndrome (SIDS) for the family system: A systematic review

The Sudden Infant Death Syndrome (SIDS) is a tragic and difficult experience for families. It involves not only the death of the baby but also the loss of a future as a parent, sibling or grandparent. The subsequent grief is multifaceted and each family member has different needs and resources. Through a systematic review of literature, we identified 24 studies between 1982 and 2021: they dealt with individual, family and couple experience when a SIDS occurs; in addition, some studies compared perinatal loss and neonatal loss with SIDS loss. Our results point out the need for an intervention that focuses on the needs of each family member and tailored around the specifics of SIDS loss rather than general grief.

Regional variation in sudden unexpected death in infancy in New Zealand

AIM

To estimate the relative risk of sudden unexpected death in infancy (SUDI) by district health board (DHB) in New Zealand after adjustment for socio-economic deprivation, ethnicity and other demographic factors.

METHODS

We conducted a population-based cohort study using data from the Integrated Data Infrastructure, a large research database containing linked data from a range of government agencies. The study population was all live births and their mothers in New Zealand from 2012 to 2018. The exposure of interest was DHB. The outcome was SUDI.

RESULTS

There were 418 068 live births in New Zealand from 2012 to 2018, and of these 415 401 (99.4%) had valid DHB data. There was considerable variation in the proportion of infants in each DHB living in the most deprived decile varying from 4.5% in Nelson, West Coast and Canterbury to 29.7% in Counties Manukau. There were 267 SUDI cases, giving an overall rate of 0.64/1000 live births during the study period (2012-2018). The SUDI rate varied from 1.11/1000 in Northland to 0.30/1000 in Waitemata and Auckland. Counties Manukau had the largest number of deaths (n = 54; rate = 1.08/1000). Five DHB regions had increased risk of SUDI compared to the reference group but, after adjustment, no DHB was significantly increased.

CONCLUSIONS

This study found that there is marked variation in SUDI risk by DHB, but this is explained by socio-economic and demographic variation within DHBs. This study emphasises the importance of the contribution of social determinants of health to SUDI.

Sudden Unexpected Death in Infancy: Current Practices in Virological Investigations and Documentation in the French Registry

OBJECTIVE

To describe pre-COVID-19 pandemic current practices in virological investigations, including type, frequency of samplings, and documented viruses, in sudden unexpected death in infancy (SUDI) and to compare results according to the cause of death.

STUDY DESIGN

Between May 2015 and December 2019, infants under 2 years of age included in the French SUDI registry were classified in one of 4 groups by causes of death according to the classification by Goldstein et al. : unexplained (SIDS), infectious, explained but noninfectious, and undetermined. Sampling sites and viruses detected were described, and then SIDS and explained deaths (control group) were compared.

RESULTS

Among 639 infants, 3.6% died of an established viral infection. From 23 sampling sites and 2238 samples, 19 virus species were detected. Overall, 43.3% of infants carried a virus, with no significant difference between SIDS infants and the control group (P = .06). We found wide variations in frequencies of samples by site (550 for nasopharynx to one for saliva). The highest positivity rate was from the nasopharynx (195/2238; 8.7%). Rhinovirus was the predominant virus detected (135/504; 26.8%), mostly in SIDS (83/254; 32.7%). We found no significant difference between positivity rates and distribution of viruses between the SIDS and control groups. At-autopsy virological analysis never contributed to determining the cause of death.

CONCLUSION

Current practices in virological investigations in SUDI are heterogeneous, with wide variability despite published guidelines. Investigations should be limited to the most relevant sites, and systematic at-autopsy sampling should be reconsidered. We found no association between virus detection and SIDS.

Risk Factors for Suffocation and Unexplained Causes of Infant Deaths

BACKGROUND

Observational studies have improved our understanding of the risk factors for sudden infant death syndrome, but separate examination of risk for sleep-related suffocation and unexplained infant deaths has been limited. We examined the association between unsafe infant sleep practices and sudden infant deaths (sleep-related suffocation and unexplained causes including sudden infant death syndrome).

METHODS

We conducted a population-based case-control study using 2016 to 2017 Centers for Disease Control and Prevention data. Controls were liveborn infants from the Pregnancy Risk Assessment Monitoring System; cases were from the Sudden Unexpected Infant Death Case Registry. We calculated risk factor prevalence among cases and controls and crude and adjusted odds ratios.

RESULTS

We included 112 sleep-related suffocation cases with 448 age-matched controls and 300 unexplained infant death cases with 1200 age-matched controls. Adjusted odds for sleep-related suffocation ranged from 18.7 (95% confidence interval [CI]: 6.8-51.3) among infants not sharing a room with their mother or caregiver to 1.9 (95% CI: 0.9-4.1) among infants with nonsupine sleep positioning. Adjusted odds for unexplained death ranged from 7.6 (95% CI: 4.7-12.2) among infants not sharing a room with their mother or caregiver to 1.6 (95% CI: 1.1-2.4) among nonsupine positioned infants.

COCLUSIONS

We confirmed previously identified risk factors for unexplained infant death and independently estimated risk factors for sleep-related suffocation. Significance of associations for suffocation followed similar patterns but was of larger magnitude. This information can be used to improve messaging about safe infant sleep.

A postmortem study of unexpected natural pediatric deaths in Egypt

Background

Identifying the causes of unexpected pediatric deaths is a clinical, medicolegal, and humanitarian requirement. This study included autopsied children aged < 18 years who suddenly died due to natural causes and excluded nonnatural deaths. The study was performed over 5 years in the Egyptian Forensic Medical Authority.

Results

The study included 244 cases, consisting of 51.6% of neonates (< 1 month), 18% of infants (1–12 months), and 30.3% of children (1–18 years). The cause of death in neonates and children was “explained natural diseases” in 73.8% and 91.9%, respectively, while it was only 45.5% in infants. Infection-related deaths account for 30.4% of all explained natural deaths. Infections were responsible for 11.8% of explained deaths in neonates, while 55% and 48.5% were in infants and children, respectively. Of the fatal infections, 60% occurred at the age of > 1 year. Pneumonia accounted for 61.8% of infection-related deaths, followed by myocarditis (12.7%) and septicemia (12.7%). Regarding systems that had fatal pathologies, respiratory causes were responsible for 64% of explained natural deaths, whereas cardiovascular and central nervous system diseases accounted for 11% and 7.7% of explained natural deaths, respectively. Considering prodromes, alarming symptoms were reported before death in 51.2% of cases, whereas death occurred without alarming manifestations in 29.9% of cases. The rest of the cases (18.9%) were abandoned children with unavailable antemortem data.

Conclusions

Present results serve as a valuable reference dataset for deaths in developmental stages in Egypt that guides forensic practitioners in managing child deaths.

Comparing asphyxia and unexplained causes of death: a retrospective cohort analysis of sleep-related infant death cases from a state child fatality review programme

OBJECTIVES

To examine the characteristics and circumstances of infants who died while sleeping or in a sleep environment and compare deaths classified as either unintentional asphyxia or an unexplained cause.

DESIGN

A retrospective cohort study.

SETTING

Data were extracted from the National Fatality Review Case Reporting System and Florida Vital Statistics databases.

PARTICIPANTS

Data on 778 sleep-related infant deaths occurring from 2014 to 2018 in Florida were analysed.

PRIMARY OUTCOME MEASURE

Cause of death classification as unintentional asphyxia or unexplained.

RESULTS

Overall, 36% (n=276) of sleep-related infant deaths in this study sample were classified as resulting from an unexplained cause compared with unintentional asphyxia. Most infants were reported to be in an adult bed (60%; n=464) and sharing a sleep surface with a person or animal (60%; n=468); less than half (44%; n=343) were reportedly placed to sleep on their back. After controlling for the influence of other independent variables, female sex (adjusted risk ratio: 1.36; 95% CI 1.06 to 1.74) and fully obstructed airway condition (adjusted risk ratio: 0.30; 95% CI 0.18 to 0.50) were associated with an unexplained cause of death.

CONCLUSIONS

The results of this analysis indicate that sleep environment hazards remain prevalent among infants who die suddenly and unexpectedly, regardless of the cause of death determination. While significant differences were observed for some factors, in many others the distributions of both demographic and incident characteristics were similar between unexplained deaths and those resulting from asphyxia. The results of this study support growing evidence that unsafe sleep environments contribute to all forms of sudden unexpected infant death, underscoring the need for standardising cause of death determination practices and promoting consistent, high-quality forensic investigations to accurately explain, monitor and prevent these deaths.

Sudden Infant Death Syndrome, Pulmonary Edema, and Sodium Toxicity: A Grounded Theory

Sudden Infant Death Syndrome (SIDS) occurs unexpectedly in an otherwise healthy infant with no identifiable cause of death following a thorough investigation. A general hypervolemic state has been identified in SIDS, and fluid in the lungs suggests the involvement of pulmonary edema and hypoxia as the cause of death. The present perspective paper reviews pathophysiological, epidemiological, and dietary evidence in SIDS. A grounded theory is presented that proposes an association of SIDS with sodium toxicity from excessive sodium chloride intake, mediated by noncardiogenic pulmonary edema, hypoxia, and alveolar damage. The peak of SIDS cases occurs in infants 2-4 months of age, who are less efficient in excreting excessive dietary sodium load. Evidence implicating sodium toxicity in SIDS includes increased levels of sodium associated with fever and with inflammatory/immune responses in the lungs. Conditions in near-miss SIDS cases are linked to dysregulated sodium, and increased sodium dietary intake suggests that sodium toxicity from a high-salt diet potentially mediates the association of seasonality and socioeconomic status with SIDS incidence. In addition, exposure to sodium toxicity meets three main criteria of the triple risk model of SIDS. The proposed pathophysiological effects of pulmonary edema related to sodium toxicity in SIDS merit further investigations.

Evidence Base for 2022 Updated Recommendations for a Safe Infant Sleeping Environment to Reduce the Risk of Sleep-Related Infant Deaths

Every year in the United States, approximately 3500 infants die of sleep-related infant deaths, including sudden infant death syndrome (SIDS) (International Statistical Classification of Diseases and Related Health Problems 10th Revision [ICD-10] R95), ill-defined deaths (ICD-10 R99), and accidental suffocation and strangulation in bed (ICD-10 W75). After a substantial decline in sleep-related deaths in the 1990s, the overall death rate attributable to sleep-related infant deaths have remained stagnant since 2000, and disparities persist. The triple risk model proposes that SIDS occurs when an infant with intrinsic vulnerability (often manifested by impaired arousal, cardiorespiratory, and/or autonomic responses) undergoes an exogenous trigger event (eg, exposure to an unsafe sleeping environment) during a critical developmental period. The American Academy of Pediatrics recommends a safe sleep environment to reduce the risk of all sleep-related deaths. This includes supine positioning; use of a firm, noninclined sleep surface; room sharing without bed sharing; and avoidance of soft bedding and overheating. Additional recommendations for SIDS risk reduction include human milk feeding; avoidance of exposure to nicotine, alcohol, marijuana, opioids, and illicit drugs; routine immunization; and use of a pacifier. New recommendations are presented regarding noninclined sleep surfaces, short-term emergency sleep locations, use of cardboard boxes as a sleep location, bed sharing, substance use, home cardiorespiratory monitors, and tummy time. In addition, additional information to assist parents, physicians, and nonphysician clinicians in assessing the risk of specific bed-sharing situations is included. The recommendations and strength of evidence for each recommendation are published in the accompanying policy statement, which is included in this issue.

Sleep-Related Infant Deaths: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment

Each year in the United States, ∼3500 infants die of sleep-related infant deaths, including sudden infant death syndrome (SIDS) (International Classification of Diseases, 10th Revision [ICD-10] R95), ill-defined deaths (ICD-10 R99), and accidental suffocation and strangulation in bed (ICD-10 W75). After a substantial decline in sleep-related deaths in the 1990s, the overall death rate attributable to sleep-related infant deaths has remained stagnant since 2000, and disparities persist. The triple risk model proposes that SIDS occurs when an infant with intrinsic vulnerability (often manifested by impaired arousal, cardiorespiratory, and/or autonomic responses) undergoes an exogenous trigger event (eg, exposure to an unsafe sleeping environment) during a critical developmental period. The American Academy of Pediatrics recommends a safe sleep environment to reduce the risk of all sleep-related deaths. This includes supine positioning; use of a firm, noninclined sleep surface; room sharing without bed sharing; and avoidance of soft bedding and overheating. Additional recommendations for SIDS risk reduction include human milk feeding; avoidance of exposure to nicotine, alcohol, marijuana, opioids, and illicit drugs; routine immunization; and use of a pacifier. New recommendations are presented regarding noninclined sleep surfaces, short-term emergency sleep locations, use of cardboard boxes as a sleep location, bed sharing, substance use, home cardiorespiratory monitors, and tummy time. Additional information to assist parents, physicians, and nonphysician clinicians in assessing the risk of specific bed-sharing situations is also included. The recommendations and strength of evidence for each recommendation are included in this policy statement. The rationale for these recommendations is discussed in detail in the accompanying technical report.

The Role of Breastfeeding in Racial and Ethnic Disparities in Sudden Unexpected Infant Death: A Population-Based Study of 13 Million Infants in the United States

Sudden unexpected infant death (SUID) disproportionately affects non-Hispanic Black (NHB) and American Indian/Alaskan Native infants, who have lower rates of breastfeeding than other groups. Using 13,077,880 live-birth certificates and 11,942 linked SUID death certificates from 2015 through 2018, we calculated odds ratios and adjusted risk differences of SUID in infants who were not breastfed across 5 racial/ethnic strata in the United States. We analyzed mediation by not breastfeeding in the race/ethnicity-SUID association. The overall SUID rate was 0.91 per 1,000 live births. NHB and American Indian/Alaskan Native infants had the highest disparity in SUID relative to non-Hispanic White infants. Overall, not breastfeeding was associated with SUID (adjusted odds ratio (aOR), 1.14; 95% confidence interval (CI): 1.10, 1.19), and the adjusted risk difference was 0.12 per 1,000 live births. The aOR of not breastfeeding for SUID was 1.07 (95% CI: 1.00, 1.14) in NHB infants and 1.29 (95% CI: 1.14, 1.46) in Hispanic infants. Breastfeeding minimally explained the higher SUID risk in NHB infants (2.3% mediated) and the lower risk in Hispanic infants (2.1% mediated) relative to non-Hispanic White infants. Competing risks likely explain the lower aOR seen in NHB infants of not breastfeeding on SUID, suggesting that social or structural determinants must be addressed to reduce racial disparities in SUID.

Indeterminacy of the Diagnosis of Sudden Infant Death Syndrome Leading to Problems with the Validity of Data

The validity of infant mortality data is essential in assessing health care quality and in the setting of preventive measures. This study explores different diagnostic procedures used to determine the cause of death across forensic settings and thus the issue of the reduced validity of data. All records from three forensic medical departments that conducted autopsies on children aged 12 months or younger (n = 204) who died during the years 2007–2016 in Moravia were included. Differences in diagnostic procedures were found to be statistically significant. Each department works with a different set of risk factors and places different emphasis on different types of examination. The most significant differences could be observed in sudden infant death syndrome and suffocation diagnosis frequency. The validity of statistical data on the causes of infant mortality is thus significantly reduced. Therefore, the possibilities of public health and social policy interventions toward preventing sudden and unexpected infant death are extraordinarily complicated by this lack of data validity.

A proof-of-concept study to construct Bayesian network decision models for supporting the categorization of sudden unexpected infant death

Sudden infant death syndrome (SIDS) remains a leading cause of infant death in high-income countries. Supporting models for categorization of sudden unexpected infant death into SIDS/non-SIDS could reduce mortality. Therefore, we aimed to develop such a tool utilizing forensic data, but the reduced number of SIDS cases renders this task inherently difficult. To overcome this, we constructed Bayesian network models according to diagnoses performed by expert pathologists and created conditional probability tables in a proof-of-concept study. In the diagnostic support model, the data of 64 sudden unexpected infant death cases was employed as the training dataset, and 16 known-risk factors, including age at death and co-sleeping, were added. In the validation study, which included 8 new cases, the models reproduced experts’ diagnoses in 4 or 5 of the 6 SIDS cases. Next, to confirm the effectiveness of this approach for onset prediction, the data from 41 SIDS cases was employed. The model predicted that the risk of SIDS in 0- to 2-month-old infants exposed to passive smoking and co-sleeping is eightfold higher than that in the general infant population, which is comparable with previously published findings. The Bayesian approach could be a promising tool for constructing SIDS prevention models.

Sudden Unexpected Death in Infancy [SUDI]: What the clinician, pathologist, coroner and researchers want to know

The loss of an apparently healthy infant is confronting for any family, puzzling for a clinician and challenging for the pathologist charged with the task of demonstrating a cause for death. The term "cot death" evolved to "sudden infant death syndrome" [SIDS] and now "sudden unexpected death in infancy [SUDI]" as the epidemiology and pathology of infant death changed. Community interventions were successful in changing sleep practices for young babies. The current research focus is on understanding genetic predispositions to unexpected death in early childhood. Whilst much has been achieved in reducing the infant mortality rate from SUDI by between 50%, and 80% in some countries, over the last 30 years, there remain challenges for improving rates of accurate diagnosis and reaching out to more vulnerable families with clearly modifiable risk factors for SUDI. These challenges directly involve the clinician through taking a systematic and detailed history and better standardised death scene evaluations with specifically accredited assessors. Better knowledge regarding circumstances of SUDI cases will help Coroners and researchers provide answers for grieving families now, and in the future contribute to further reductions in the rate of SUDI in communities across the world.

Barriers to consistent and reliable investigation of sudden unexpected infant death: Perspectives from law enforcement

Despite persistent efforts to advance infant death investigation, most sudden unexpected infant deaths (SUIDs) remain unexplained. Law enforcement officials contribute to SUID investigations throughout the United States, but their impacts on these investigations have not been adequately examined. In this exploratory study, 26 law enforcement officials were interviewed about their experiences and perspectives with SUID investigations. Thematic analysis of qualitative data revealed three specific difficulties law enforcement encounter during SUID investigations: (1) inadequate preparation; (2) overwhelming emotions; and (3) a victim-suspect dilemma. Findings indicate that these barriers may inhibit consistent and reliable investigation of infant death and, therefore, may impede the cause and manner of death determinations. Participants' narratives also offered insights into potential solutions, including expanded SUID training for law enforcement and use of checklists, such as the Sudden Unexpected Infant Death Investigation Reporting Form. The impacts of overwhelming emotions confronted during SUID investigation warrant further study. The victim-suspect dilemma stems from the inability of law enforcement to conclusively eliminate the possibility of homicide. This dilemma may be resolved through a clear distinction between interactions with potential evidence and interactions with the family. Law enforcement must be trained to treat all SUID families in a compassionate and non-accusatory manner, while investigating all SUID with careful attention to detail that is essential in any potential homicide investigation. A consistent, meticulous, and compassionate approach to SUID investigations will improve the reliability of information obtained and offer the best opportunity for providing answers to grieving parents.

Renewed Attention Needed for Prevention of Sudden Unexpected Death in Infancy in the Netherlands

Background: The incidence of sudden unexpected death in infancy (SUDI), which includes sudden infant death syndrome (SIDS), has declined in developed countries since the 1980s, including the Netherlands. To identify improvement opportunities in SUDI prevention, we monitored the adherence of parents to the prevention advice on infant care habits over the past 20 years, especially in relation to the SUDI incidence over time. Potential changes in parental adherence between the latest surveys are of specific interest, as these indicate where current focus is needed. Methods: Description of the prevalence of infant care factors related to the risk of SUDI, assessed from five Dutch national surveys from 1999 to 2017 among parents of infants under 12 months, and analysis of the potential differences in these prevalences between the two latest surveys in 2010/11 and 2017 with a z-test. Results: Supine sleeping position decreased from the highest prevalence of 92% in 2010/11, to 83% in 2017. Sleep sack use has increased to 55%, the highest prevalence up to now. Avoiding a duvet has remained reasonably stable since 2002/03 and now 95% of parents do not use a duvet. The prevalence of room-sharing, without sharing the bed, increased from 14% in 1999 to the highest prevalence in 2017 (31%). However, also bed-sharing almost doubled from 5.6% in 2010/11 to 10% in 2017. Breastfeeding decreased between 1999 and 2010/11, but increased from 34% in 2010/11 to 42% in 2017. An increased prevalence of mothers who abstained from smoking during pregnancy, as well as both parents not smoking, was observed, although mostly higher educated parents showed this beneficial behavior. Discussion and Conclusion: Much has already been achieved first by decreasing prone sleeping since the 80's, and subsequently promoting supine as the safest sleep position. The decrease in duvet use and smoking, and an increase in breastfeeding have also had impact. Indications of a recent decreased prevalence of the supine sleeping position and higher prevalence of bed-sharing might relate to the slightly increasing SUDI incidence in the Netherlands. Renewed attention for prevention of SUDI and specific advice targeting high-risk groups is needed. Modern, picture driven information via internet is recommended.

Risk and Preventive Factors for SUDI: Need We Adjust the Current Prevention Advice in a Low-Incidence Country

Background: The incidence of Sudden Unexpected Death in Infancy (SUDI) is low in the Netherlands, with an incidence rate of 0.18 per 1,000 live births. Therefore, prevention advice may receive less attention, potentially leading to increasing incidence rates. It is currently unknown whether the risks for SUDI changed in the Netherlands, and if other risk factors might be present. The aim of this study was to examine the current risks and preventive factors for SUDI in Dutch infants, in order to determine if it is necessary to adapt the prevention advice toward the current needs. Methods: A case-control study was conducted comparing SUDI cases aged <12 months from 2014-2020 in the Netherlands (n = 47), to a Dutch national survey control group from 2017 including infants <12 months of age (n = 1,192). Results: Elevated risks for several well-known factors were observed, namely: duvet use (aOR = 8.6), mother smoked during pregnancy (aOR = 9.7), or after pregnancy (aOR = 5.4) and the prone sleeping position (aOR = 4.6). Reduced risks were observed for the well-known factors: room-sharing (aOR = 0.3), sleep sack use (aOR = 0.3), breastfeeding (aOR = 0.3), and the use of a pacifier (aOR = 0.4). For infants <4 months, the risk for SUDI was higher when bed-sharing (aOR = 3.3), and lower when room-sharing (aOR = 0.2) compared to older infants. For older infants, the sleep sack was found to be more protective (aOR = 0.2). A high risk for SUDI when bed-sharing was found when mother smoked, smoked during pregnancy, or if the infant did not receive any breastfeeding (respectively aOR = 17.7, aOR = 10.8, aOR = 9.2). Conclusions: Internationally known factors related to the sudden unexpected death of infants were also found in this study. Relatively new findings are related to specific groups of infants, in which the strengths of these risk factors differed. In a low-incidence country like the Netherlands, renewed attention to the current prevention advice is needed. Furthermore, additional attention for prevention measures in low educated groups, and additional advice specifically targeting high-risk groups is recommended.

Half Century Since SIDS: A Reappraisal of Terminology

After a sudden infant death, parents and caregivers need accurate and open communication about why their infant died. Communicating tragic news about a child's death to families and caregivers is difficult. Shared and consistent terminology is essential for pediatricians, other physicians, and nonphysician clinicians to improve communication with families and among themselves. When families do not have complete information about why their child died, pediatricians will not be able to support them through the process and make appropriate referrals for pediatric specialty and mental health care. Families can only speculate about the cause and may blame themselves or others for the infant's death. The terminology used to describe infant deaths that occur suddenly and unexpectedly includes an assortment of terms that vary across and among pediatrician, other physician, or nonphysician clinician disciplines. Having consistent terminology is critical to improve the understanding of the etiology, pathophysiology, and epidemiology of these deaths and communicate with families. A lack of consistent terminology also makes it difficult to reliably monitor trends in mortality and hampers the ability to develop effective interventions. This report describes the history of sudden infant death terminology and summarizes the debate over the terminology and the resulting diagnostic shift of these deaths. This information is to assist pediatricians, other physicians, and nonphysician clinicians in caring for families during this difficult time. The importance of consistent terminology is outlined, followed by a summary of progress toward consensus. Recommendations for pediatricians, other physicians, and nonphysician clinicians are proposed.

Sudden Death in Adults: A Practical Flow Chart for Pathologist Guidance

The medico-legal term "sudden death (SD)" refers to those deaths that are not preceded by significant symptoms. SD in apparently healthy individuals (newborn through to adults) represents a challenge for medical examiners, law enforcement officers, and society as a whole. This review aims to introduce a useful flowchart that should be applied in all cases of SD. Particularly, this flowchart mixes the data obtained through an up-to-date literature review and a revision of the latest version of guidelines for autopsy investigation of sudden cardiac death (SCD) in order to support medico-legal investigation. In light of this review, following the suggested flowchart step-by-step, the forensic pathologist will be able to apply all the indications of the scientific community to real cases. Moreover, it will be possible to answer all questions relative to SD, such as: death may be attributable to cardiac disease or to other causes, the nature of the cardiac disease (defining whether the mechanism was arrhythmic or mechanical), whether the condition causing SD may be inherited (with subsequent genetic counseling), the assumption of toxic or illicit drugs, traumas, and other unnatural causes.

Examining the Relationship Between Sleep-Related Infant Deaths and Social Determinants of Health in Urban Communities

In 2017, sleep-related infant deaths (SRID) accounted for about 3600 deaths in the USA. The SRID rate for African American infants (186. 41 per 100,000 live births) is more than twice that of Caucasian American infants (85. 43 per 100,000 live births) (Centers for Disease and Prevention, July 2020).

PURPOSE

The purpose of this article is to develop a case for considering the relationship between racial disparities in SRID and social determinants of health (SDOH) in impoverished communities. The later has been related to chronic stress impacting biological and psychological functioning. The authors advocate that undesirable SDOH be regarded when developing safe sleep strategies for at risk communities, since chronic stress can impact psychological and biologic functioning, possibly manifesting in inconsistent safe sleep practices by caregivers.

METHODS

An adapted environmental scan (AES), using SRID and SDOH data from impoverished communities, was used to illustrate the comparison of SRID and SDOH in contrasting Baltimore neighborhoods.

RESULTS

The AES revealed a match between disparities in SRID and SDOH (e.g., educational achievement, unemployment, poverty, poor housing, and violence). The comparison between the SDOH and SRID increases together for named impoverished neighborhoods, as compared to those with low SRID rates in Baltimore.

CONCLUSION

Rather than limit safe sleep interventions to crib and infant sleeper give-aways, for example, hazardous SDOH seen in impoverished communities should be addressed. We posit that these results will stimulate discussion for well-placed and financed programs, along with policies that focus on decreasing SRID by improving poor SDOH.

The parental role before and after SIDS

Role confusion is a prominent constituent symptom of Prolonged Grief Disorder in parents after their infants die from sudden infant death syndrome (SIDS). We interviewed 31 parents of SIDS infants 2-5 years post-loss examining the parental role before death, at the time of loss, and in bereavement. Thematic analysis found disruption of the role and re-imagined responsibilities for their child's physical security, emotional security, and meaning. Tasks within these domains changed from concrete and apparent to representational and self-generated. Parents in bereavement locate ongoing, imperative parental responsibilities, particularly asserting their child's meaningful place in the world and in their family.

Explaining Sudden Unexpected Infant Deaths, 2011-2017

BACKGROUND

Sudden unexpected infant death (SUID) represents a broad group of explained and unexplained infant deaths (<1 year old). Explaining why SUID occurs is critical to understanding etiology and prevention. Death certificate data cannot differentiate explained from unexplained SUID cases nor describe the surrounding circumstances. We report SUID rates by explained and unexplained categories and describe demographics and history of recent injury or illness using the Centers for Disease Control and Prevention SUID Case Registry.

METHODS

The registry is a population-based surveillance system built on Child Death Review programs. Data are derived from multiple sources, including death certificates, scene investigations, and autopsy reports. Cases included SUIDs reported by states or jurisdictions participating in the registry during 2011-2017. Cases were classified into explained and unexplained categories by using the registry's classification system. Frequencies, percentages, and mortality rates per 100 000 live births were calculated.

RESULTS

Of the 4929 SUID cases, 82% were categorized as unexplained. Among all cases, 73% had complete case information. Most SUIDs (72%) occurred in an unsafe sleep environment. The SUID mortality rate was 97.3 per 100 000 live births. Among explained and possible suffocation deaths, ∼75% resulted from airway obstruction attributed to soft bedding.

CONCLUSIONS

Unsafe sleep factors were common in explained and unexplained SUID cases, but deaths could only be classified as explained suffocation for ∼20% of cases. Further analysis of unexplained deaths, including continued improvements to death scene investigation and documentation, may generate hypotheses for physiologic and genetic research, advance our understanding of gaps in SUID investigation, and enhance our understanding of infants at highest risk.

Classification of sleep-related sudden unexpected death in infancy: A national survey

AIM

To identify how British Child Death Overview Panels (CDOPs) and paediatric pathologists classify cause of death for sleep-related Sudden Unexpected Death in Infancy (SUDI). To determine compliance with national requirements for SUDI investigation.

METHODS

Electronic survey of CDOPs and pathologists using three vignettes of SUDI cases illustrating: accidental asphyxia, typical Sudden Infant Death Syndrome (SIDS) and SIDS with co-sleeping.

RESULTS

Thirty-eight (41%) of 92 CDOPs returned questionnaires, and 32 were complete. Thirteen (14%) of 90 pathologists returned complete questionnaires. Thirty-one (97%) CDOPs and 7 (53%) pathologists agreed with the cause of death in the accidental asphyxia case; 24 (75%) CDOPs and 9 (69%) pathologists in the typical SIDS case; and 11 (34%) CDOPs and 1 (8%) pathologist in the co-sleeping SIDS case. Pathologists used the terms SUDI or unascertained as the cause of death for the accidental asphyxia case (46%) and the co-sleeping SIDS case (77%). These terms were used by CDOPs for the typical SIDS case (25%) and the co-sleeping SIDS case (41%). Seventeen (46%) CDOPs reported compliance with guidelines for investigation in more than 75% of cases.

CONCLUSION

There is wide variation in classification of deaths, with only limited agreement between CDOPs and pathologists. The terms SIDS and accidental asphyxia are underused, even in typical cases.

Genetic Factors Underlying Sudden Infant Death Syndrome

Sudden Infant Death syndrome (SIDS) is a diagnosis of exclusion. Decades of research have made steady gains in understanding plausible mechanisms of terminal events. Current evidence suggests SIDS includes heterogeneous biological conditions, such as metabolic, cardiac, neurologic, respiratory, and infectious conditions. Here we review genetic studies that address each of these areas in SIDS cases and cohorts, providing a broad view of the genetic underpinnings of this devastating phenomenon. The current literature has established a role for monogenic genetic causes of SIDS mortality in a subset of cases. To expand upon our current knowledge of disease-causing genetic variants in SIDS cohorts and their mechanisms, future genetic studies may employ functional assessments of implicated variants, broader genetic tests, and the inclusion of parental genetic data and family history information.

Seizure-related deaths in children: The expanding spectrum

Although seizures are common in children, they are often overlooked as a potential cause of death. Febrile and nonfebrile seizures can be fatal in children with or without an epilepsy diagnosis and may go unrecognized by parents or physicians. Sudden unexpected infant deaths, sudden unexplained death in childhood, and sudden unexpected death in epilepsy share clinical, neuropathological, and genetic features, including male predominance, unwitnessed deaths, death during sleep, discovery in the prone position, hippocampal abnormalities, and variants in genes regulating cardiac and neuronal excitability. Additionally, epidemiological studies reveal that miscarriages are more common among individuals with a personal or family history of epilepsy, suggesting that some fetal losses may result from epileptic factors. The spectrum of seizure-related deaths in pediatrics is wide and underappreciated; accurately estimating this mortality and understanding its mechanism in children is critical to developing effective education and interventions to prevent these tragedies.

The Genetics of Sudden Infant Death Syndrome-Towards a Gene Reference Resource

Sudden infant death syndrome (SIDS) is the unexpected death of an infant under one year of age that remains unexplained after a thorough investigation. Despite SIDS remaining a diagnosis of exclusion with an unexplained etiology, it is widely accepted that SIDS can be caused by environmental and/or biological factors, with multiple underlying candidate genes. However, the lack of biomarkers raises questions as to why genetic studies on SIDS to date are unable to provide a clearer understanding of the disease etiology. We sought to improve the identification of SIDS-associated genes by reviewing the SIDS genetic literature and objectively categorizing and scoring the reported genes based on the strength of evidence (from C1 (high) to C5 (low)). This was followed by analyses of function, associations between genes, the enrichment of gene ontology (GO) terms, and pathways and gender difference in tissue gene expression. We constructed a curated database for SIDS gene candidates consisting of 109 genes, 14 of which received a category 4 (C4) and 95 genes received the lowest category of C5. That none of the genes was classified into the higher categories indicates the low level of supporting evidence. We found that genes of both scoring categories show distinct networks and are highly diverse in function and involved in many GO terms and pathways, in agreement with the perception of SIDS as a heterogeneous syndrome. Genes of both scoring categories are part of the cardiac system, muscle, and ion channels, whereas immune-related functions showed enrichment for C4 genes. A limited association was found with neural development. Overall, inconsistent reports and missing metadata contribute to the ambiguity of genetic studies. Considering those parameters could help improve the identification of at-risk SIDS genes. However, the field is still far from offering a full-pledged genetic test to identify at-risk infants and is still hampered with methodological challenges and misunderstandings of the vulnerabilities of vital biological mechanisms.

Aquaporin-1 and aquaporin-9 gene variations in sudden infant death syndrome

Several studies have indicated that a vulnerability in the development and regulation of brain function is involved in sudden infant death syndrome (SIDS). The aim of this study was to investigate the genes encoding the brain aquaporins (AQPs) AQP1 and AQP9 in SIDS. The hypothesis was that specific variants of these genes are part of the genetic vulnerability predisposing infants to sudden unexpected death. The study included 168 SIDS cases with a median age of 15.5 (range 2–52) weeks and 372 adolescent/adult deceased controls with a median age of 44 (range 11–91) years. In the AQP1 gene, the rs17159702 CC/CT genotypes were found to be associated with SIDS (p = 0.02). In the AQP9 gene, the combination of a TT genotype of rs8042354, rs2292711 and rs13329178 was more frequent in SIDS cases than in controls (p = 0.03). In the SIDS group, an association was found between genetic variations in the AQP1 gene and maternal smoking and between the 3xTT combination in the AQP9 gene and being found lifeless in a prone position. In conclusion, this study adds further evidence to the involvement of brain aquaporins in SIDS, suggesting that specific variants of AQP genes constitute a genetic predisposition, making the infant vulnerable to sudden death together with external risk factors and probably other genetic factors.

Death-scene investigations contribute to legal protection in unexpected child deaths in Norway

AIM

This study reviewed cases of sudden unexpected child deaths in Norway to determine the significance of death-scene investigations (DSIs) in establishing cause and manner of death, and thereby it is relevance to legal protection.

METHODS

Data from forensic autopsy reports and DSIs were collected and analysed for cases of unexpected deaths in children below 4 years of age in Norway during 2010-2016.

RESULTS

Out of 141 cases, the death scene was investigated as a voluntary procedure in 75 cases and by the police in 41 cases. The cause of death remained unexplained in 81/141 (57%) of the cases, of which 46/141 (33%) met the criteria for sudden infant death syndrome (SIDS) or sudden unexplained death in early childhood (SUDC). The manner of death was determined in 102/141 (72%). Voluntary DSI increased the ability to rule out accidental suffocation, facilitated evaluations of environmental risk factors and enabled detection of possible neglect.

CONCLUSION

Death-scene investigations illuminate uncertainty about the cause of death, especially in grey-area cases where accidental suffocation, neglect or abuse is suspected. Knowledge about the course of events and the cause of death enhances both the child's and the caregiver's legal protection. Death-scene investigations should therefore be mandatory.

Pathologizing the Unknown: A Sociological Explanation for the (Mis-)Use of Sudden Infant Death Syndrome as a Diagnosis

Sudden infant death syndrome (SIDS) is a diagnosis given to infants who die suddenly and unexpectedly before the age of one. After decades of research into SIDS, little has been conclusively determined regarding the etiology of this phenomenon. While SIDS deaths are in reality undetermined deaths, there is resistance to abandon SIDS and synonymous terminology. This paper identifies the social functions that a diagnosis of SIDS provides both to the families of the deceased, as well as the physicians who treat them. It is suggested that these social functions help to explain why, despite being inaccurate and misleading, SIDS is still widely used today. It is argued, however, that the forensic pathology and medical community as a whole should lead a systematic shift away from the use of SIDS as a diagnosis. Adopting more medically-appropriate terminology would better serve the goals of the medical profession and the families they serve.

Univariate Analysis of Short-Chain Fatty Acids Related to Sudden Infant Death Syndrome

Sudden infant death syndrome (SIDS) is defined as the death of a child under one year of age, during sleep, without apparent cause, after exhaustive investigation, so it is a diagnosis of exclusion. SIDS is the principal cause of death in industrialized countries. Inborn errors of metabolism (IEM) have been related to SIDS. These errors are a group of conditions characterized by the accumulation of toxic substances usually produced by an enzyme defect and there are thousands of them and included are the disorders of the β-oxidation cycle, similarly to what can affect the metabolism of different types of fatty acid chain (within these, short chain fatty acids (SCFAs)). In this work, an analysis of postmortem SCFAs profiles of children who died due to SIDS is proposed. Initially, a set of features containing SCFAs information, obtained from the NIH Common Fund's National Metabolomics Data Repository (NMDR) is submitted to an univariate analysis, developing a model based on the relationship between each feature and the binary output (death due to SIDS or not), obtaining 11 univariate models. Then, each model is validated, calculating their receiver operating characteristic curve (ROC curve) and area under the ROC curve (AUC) value. For those features whose models presented an AUC value higher than 0.650, a new multivariate model is constructed, in order to validate its behavior in comparison to the univariate models. In addition, a comparison between this multivariate model and a model developed based on the whole set of features is finally performed. From the results, it can be observed that each SCFA which comprises of the SFCAs profile, has a relationship with SIDS and could help in risk identification.

Increased thymus weight in sudden infant death syndrome compared to controls: The role of sub-clinical infections

OBJECTIVE

The goal of the present investigation is to analyze thymus, brain, heart, liver, and kidney weights in SIDS victims compared to controls.

BACKGROUND

Epidemiologic risk factors for SIDS (eg, male gender, genetic, obstetric, environmental, smoke exposure, nonbreastfeeding, etc.) are consistent with an infectious process underlying many of these deaths.

METHODS

Data from autopsy reports on 585 SIDS victims and comparison deaths (n = 294 control, n = 291 SIDS) were analyzed. Cases were obtained from Australia (n = 184 controls, n = 98 SIDS) and Russia (n = 122 controls, n = 181 SIDS). Log₁₀ transform of thymus and other organ weights was computed because variables were skewed. Multivariate analysis of variance (MANOVA) of standardized log values were age-adjusted by multivariate analysis of covariance (MANCOVA). The standardized log₁₀ thymus residual adjusted for age, brain and liver weights was computed for the final analysis.

RESULTS

After controlling for age by MANCOVA, thymus, body, brain and liver weights were significantly higher among SIDS compared to non-SIDS victims. The largest difference as between covariate-adjusted log₁₀ non-SIDS thymus weight differed (mean = 1.423, 95% CI: 1.393-1.452) and log₁₀ non-SIDS thymus weight (mean = 1.269, 95% CI: 1.243-1.294) were significantly different (P < .0001). Heart weight was significantly lower in SIDS victims.

DISCUSSION

When adjusted for confounders (age, body, and organ weights), SIDS victims have a significantly heavier thymus and brain compared to non-SIDS controls who died of trauma. This finding supports previously published studies that link infection to SIDS deaths.