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

OBJECTIVES

Using the National Child Mortality Database, this work aims to investigate background characteristics and risk factors in the sleeping environment associated with sudden infant death syndrome (SIDS) and compare the prevalence with previous English SIDS case-control studies.

DESIGN

Cohort of SIDS in 2020 compared with a combined analysis of two case-control studies conducted in 1993-1996 and 2003-2006.

SETTING

England, UK PARTICIPANTS: 138 SIDS deaths in 2020 compared with 402 SIDS deaths and 1387 age-equivalent surviving controls, combined from previous studies.

RESULTS

The increased vulnerability of SIDS infants identified in previous studies has become more marked. The infants who died in 2020 were younger (median=66 days (IQR: 34-118) vs 86 days (IQR: 52-148), p=0.003) with an increased prevalence of low birth weight (30.5% vs 21.6%, p=0.04) and preterm births (29.6% vs 19.3%, p=0.012). The excess of socioeconomically deprived families, male infants and high levels of maternal smoking during pregnancy were still evident. Among recent deaths, fewer infants were put down or found on their side; however, there was no significant change in the proportion of infants who were put down (15.6% vs 14.6%, p=0.81) and found prone (40.4% vs 35.3%, p=0.37), despite population wide risk reduction advice over three decades. The proportional increase observed in 2003-2006 of half the deaths occurring while sleeping next to an adult was maintained in 2020, and for the vast majority (90%), this was in hazardous circumstances (adult had consumed alcohol, smoked, slept on a sofa, or the infant was premature or low birth weight and less than 3 months old). More deaths also occurred when there was a disruption in infant care routine compared with previous observations (52.6% vs 20.7%, p<0.001).

CONCLUSIONS

A more targeted approach is needed with vulnerable families emphasising the importance of sleeping infants on their back and proactive planning infant sleep when there are disruptions to the normal routine, in particular to avoid hazardous co-sleeping.

Are non-invasive or minimally invasive autopsy techniques for detecting cause of death in prenates, neonates and infants accurate? A systematic review of diagnostic test accuracy

OBJECTIVES

To assess the diagnostic accuracy of non-invasive or minimally invasive autopsy techniques in deaths under 1 year of age.

DESIGN

This is a systematic review of diagnostic test accuracy. The protocol is registered on PROSPERO.

PARTICIPANTS

Deaths from conception to one adjusted year of age.

SEARCH METHODS

MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCO), the Cochrane Library, Scopus and grey literature sources were searched from inception to November 2021.

DIAGNOSTIC TESTS

Non-invasive or minimally invasive diagnostic tests as an alternative to traditional autopsy.

DATA COLLECTION AND ANALYSIS

Studies were included if participants were under one adjusted year of age, with index tests conducted prior to the reference standard.Data were extracted from eligible studies using piloted forms. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted following the Synthesis without Meta-Analysis guidelines. Vote counting was used to assess the direction of effect.

MAIN OUTCOME MEASURES

Direction of effect was expressed as percentage of patients per study.

FINDINGS

We included 54 direct evidence studies (68 articles/trials), encompassing 3268 cases and eight index tests. The direction of effect was positive for postmortem ultrasound and antenatal echography, although with varying levels of success. Conversely, the direction of effect was against virtual autopsy. For the remaining tests, the direction of effect was inconclusive.A further 134 indirect evidence studies (135 articles/trials) were included, encompassing 6242 perinatal cases. The addition of these results had minimal impact on the direct findings yet did reveal other techniques, which may be favourable alternatives to autopsy.Seven trial registrations were included but yielded no results.

CONCLUSIONS

Current evidence is insufficient to make firm conclusions about the generalised use of non-invasive or minimally invasive autopsy techniques in relation to all perinatal population groups.PROSPERO registration numberCRD42021223254.

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.

Trends in infant mortality: an evaluation of forensic autopsied infants in Eastern Denmark over 39 years

BACKGROUND

SIDS is a diagnosis of exclusion applied to the death of an infant < 1 year of age after an extensive post-mortem investigation. From 1980 to 2018, a total of 870 infants have been autopsied at the Section of Forensic Pathology, Department of Forensic Medicine, UCPH, covering East Denmark. In the same period, Danish national guidelines for infant care have been revised to avoid infants dying of SIDS.

OBJECTIVE

This study aimed to describe trends in infant autopsies regarding cause and manner of death, gender, age, month of death, sleeping position, and bed-sharing. The trends were compared to the change in national SIDS guidelines during the period of this study.

DESIGN

Information from autopsy reports from 1980 to 2018 were collected into 55 categories designed specifically for this study. Data from 7 of these categories were chosen and processed in Excel for basic epidemiological comparison.

RESULTS

The trends show that most infants in the study die of natural manner and most predominant causes of death are SIDS, infection, and congenital malformations. A change in national guidelines in 1991 recommending supine- or side sleeping position coincided with a reduction in the overall infant mortality and cases of SIDS. The peak age in the cohort is 90 days, but stratification in decades shows the infants dying younger each decade. Through the study period, the number of infants found dead sleeping in the prone position has declined. Relatively more infants in this cohort have been found dead while bed-sharing, even though the prevalence of these cases has remained largely the same for four decades.

Cot Death: History of an Iatrogenic Disaster

Since antiquity, cot death has been explained as accidental suffocation, overlaying, or smothering. Parents were blamed for neglect or drunkenness. A cage called arcuccio was invented around 1570 to protect the sleeping infant. Up to the 19th century, accidents were registered as natural causes of death. From 1830, accidental suffocation became unacceptable for physicians and legislators, and "natural" explanations for the catastrophe were sought, with parents being consoled rather than blamed. Two assumed causes had serious consequences: thymus hyperplasia was irradiated, causing thyroid cancer, and the concept of central apnea was widely accepted, which led to home monitors and distracted from epidemiological evidence. Prone sleeping originated in the 1930s and from 1944, it was associated with cot death. However, from the 1960s, many authors recommended prone sleeping for infants, and many countries adopted the advice. A worldwide epidemic followed, peaking at 2‰ in England and Wales and 5‰ in New Zealand in the 1980s. Although epidemiological evidence was available by 1970, the first intervention was initiated in the Netherlands in 1989. Cot death disappeared almost entirely wherever prone sleeping was avoided. This strongly supports the assumption that prone sleeping has the greatest influence on the disorder, and that the epidemic resulted from wrong advice.