Changes in background characteristics and risk factors among SIDS infants in England: cohort comparisons from 1993 to 2020

Baby Sleep Project Protocol: a realist evaluation of an intervention to reduce preventable infant mortality

INTRODUCTION

In the UK, approximately 300 infants each year die suddenly and unexpectedly, with most deaths remaining unexplained. Population-wide 'Safer Sleep' messages have brought rates down but remaining deaths now predominantly occur within families experiencing poverty. Many of these deaths may be preventable as the majority have known, avoidable risks present. New resources and tools for health professionals and families have been developed to address modifiable barriers to implementing safer sleep advice in this priority group of families. This study aims to understand how the Baby Sleep Project resources work to improve the uptake of safer sleep advice, including for whom, and in what contexts they work best.

METHODS AND ANALYSIS

Realist evaluation will be used, including both qualitative and quantitative methods. Data will be collected both pre- and post-health professional training in the new resources. We will invite neonatal staff, health visitors and family nurse partnerships nurses, and primary caregivers of infants to take part. We will carry out qualitative interviews with health professionals and caregivers. Quantitative surveys looking at implementation for health professionals, changes in infant care knowledge and practice, and parenting self-efficacy will be conducted with caregivers. Mechanisms of action, contexts and outcomes from the new resources will be tested against the initial programme theory. The findings from this research will inform evidence-based explanations of how to improve the uptake of health advice in priority populations.

ETHICS AND DISSEMINATION

The study was given a favourable opinion by the South West-Frenchay Research Ethics Committee (ref: 23/SW/0119). We will publish our findings in academic journals and talk about them at conferences. We will make sure the people who took part in the study hear about them first. If the resources are shown to be useful, we will work with charities and the National Health Service to roll them out across the whole of the UK.

TRIAL REGISTRATION NUMBER

ISRCTN3364337.

The vicious spiral in Sudden Infant Death Syndrome

Sudden Infant Death Syndrome (SIDS) is the sudden and unexpected death of an otherwise healthy infant less than 1 year of age where the cause of death remains unexplained after a thorough post-mortem investigation and evaluation of the circumstances. Epidemiological, clinical, biochemical, immunological and pathological evidence indicates that three factors must coincide for SIDS to occur: a vulnerable developmental stage of the immune system and central nervous system in the infant, predisposing factors, and external trigger events. This model is referred to as the fatal triangle or triple risk hypothesis. The concept of a vicious spiral in SIDS, starting with the fatal triangle and ending in death, is proposed as a model to understand the death mechanism. The vicious spiral is initiated by a mucosal infection and immune activation in the upper respiratory and digestive tracts, increased production of cytokines, and an overstimulation of the immature and rapidly developing immune system. A second trigger is the prone sleeping position, which may lead to rebreathing and hypercapnia, in addition to intensify the immune stimulation. In susceptible infants, this induces an aberrant cytokine production that affects sleep regulation, induces hyperthermia, and disrupts arousal mechanisms. In turn, this initiates downregulation of respiration and hypoxemia, which is worsened by nicotine. Inefficient autoresuscitation results in severe hypoxia and accumulation of hypoxic markers which, if not prevented by a normally functioning serotonergic network, contribute to a self-amplifying vicious spiral that eventually leads to coma and death. The purpose of this review is to summarize the research that underpins the concept of the vicious spiral.

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.

Prenatal and postnatal factors associated with sudden infant death syndrome: an umbrella review of meta-analyses

BACKGROUND

Comprehensive quantitative evidence on the risk and protective factors for sudden infant death syndrome (SIDS) effects is lacking. We investigated the risk and protective factors related to SIDS.

METHODS

We conducted an umbrella review of meta-analyses of observational and interventional studies assessing SIDS-related factors. PubMed/MEDLINE, Embase, EBSCO, and Google Scholar were searched from inception until January 18, 2023. Data extraction, quality assessment, and certainty of evidence were assessed by using A Measurement Tool Assessment Systematic Reviews 2 following PRISMA guidelines. According to observational evidence, credibility was graded and classified by class and quality of evidence (CE; convincing, highly suggestive, suggestive, weak, or not significant). Our study protocol was registered with PROSPERO (CRD42023458696). The risk and protective factors related to SIDS are presented as equivalent odds ratios (eORs).

RESULTS

We identified eight original meta-analyses, including 152 original articles, covering 12 unique risk and protective factors for SIDS across 21 countries/regions and five continents. Several risk factors, including prenatal drug exposure [eOR = 7.84 (95% CI = 4.81-12.79), CE = highly suggestive], prenatal opioid exposure [9.55 (95% CI = 4.87-18.72), CE = suggestive], prenatal methadone exposure [9.52 (95% CI = 3.34-27.10), CE = weak], prenatal cocaine exposure [4.38 (95% CI = 1.95-9.86), CE = weak], prenatal maternal smoking [2.25 (95% CI = 1.95-2.60), CE = highly suggestive], postnatal maternal smoking [1.97 (95% CI = 1.75-2.22), CE = weak], bed sharing [2.89 (95% CI = 1.81-4.60), CE = weak], and infants found with heads covered by bedclothes after last sleep [11.01 (95% CI = 5.40-22.45), CE = suggestive], were identified. On the other hand, three protective factors, namely, breastfeeding [0.57 (95% CI = 0.39-0.83), CE = non-significant], supine sleeping position [0.48 (95% CI = 0.37-0.63), CE = suggestive], and pacifier use [0.44 (95% CI = 0.30-0.65), CE = weak], were also identified.

CONCLUSIONS

Based on the evidence, we propose several risk and protective factors for SIDS. This study suggests the need for further studies on SIDS-related factors supported by weak credibility, no association, or a lack of adequate research.

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.