We used data from the National Child Death Review Case Reporting System (NCDR-CRS), which captures information reported by CDR teams. Our retrospective review consisted of SUID cases reported by state and local CDR teams participating in the initial years of the SUID Case Registry. CDR and the SUID Case Registry programs and practices have been described elsewhere.^16,17 Briefly, CDR teams in states participating in the SUID Case Registry gather and review information about SUID cases from multiple data sources, including death certificates, autopsy reports, coroner/medical examiner records, law enforcement reports, emergency medical services reports, photographs and reports from doll reenactments, child protective services records, hospital reports, medical records, death scene photos, and pathology reports. Multidisciplinary CDR teams summarize findings and recommendations from reviews and enter this information into the NCDR-CRS. Data then undergo quality assurance measures at the state level. Data use agreements with participating states allow us to use these data and ensure that the state’s data remain confidential.

For this analysis, we selected SUID cases that occurred from 2010 through 2012 and were entered into the NCDR-CRS Version 2.2s (Figure; available at www.jpeds.com). Eligible cases were resident infant deaths (<365 days old) with any of the following causes reported on the death certificate: unknown, undetermined, SIDS, SUID, unintentional sleep-related asphyxia/suffocation/strangulation, unspecified suffocation, cardiac or respiratory arrest without other well-defined causes, or ill-defined causes with potentially contributing unsafe sleep factors, except if manner of death was reported as homicide. Case numbers varied across study years. Two states joined the SUID Case Registry in 2011 and therefore did not contribute any cases for 2010. Additionally, 2 states had not submitted the 2012 death year cohort at the time of this analysis. Our final sample included 770 cases (Figure).

We examined variables related to DSI, infant sleep environment, and autopsy available in the NCDR-CRS Version 2.2s. These variables are described in the NCDR-CRS data dictionary.¹⁸ Most study variables were derived from single questions in the NCDR-CRS. For the remaining study variables, we created composite variables by combining multiple questions (Table I).

Based on the composite variable for DSI performed, 98% of cases had a DSI, ranging from 100% in states A, E, and G to 95% in state F (Table II). For all states combined, narrative description of the circumstances (90%) and witness interviews (88%) were reported most frequently. The SUIDIRF or jurisdictional equivalent (71%), scene photos (68%), any scene re-creation (45%), and scene re-creation with a doll (37%) were reported less frequently. The SUIDIRF or jurisdictional equivalent had the largest range when compared across states; ranging from 100% completion in state E to 24% completion in state A. Narrative description of circumstances had the narrowest range, from 99% completion in state A to 85% completion in state C. Variation in the percentages of DSI components reported as complete was observed depending on the state’s type of medicolegal system.

Within each state, the consistency of reporting across DSI components varied. State E had the highest percentages of reported DSI components, ranging from 100% completion of the SUIDIRF or jurisdictional equivalent to 58% completion of a scene re-creation with a doll. State A had the lowest percentages and the most variation in reported DSI components, ranging from 99% completion of a narrative description of circumstances to 13% completion for scene re-creation with a doll. For all states and DSI components combined, the average missing/unknown was 15%, ranging from state A with 58% missing/unknown for SUIDIRF or jurisdictional equivalent to states E and G with 0% missing/unknown for SUIDIRF or jurisdictional equivalent. States B and C had the highest average missing/unknown for all DSI components combined (22%).

Implementation of thorough and consistent DSI and autopsy practices increases understanding of the circumstances surrounding SUID and improves accuracy in diagnosing the causes of SUID. Having reliable and accurate data about SUID cases improves the ability to monitor trends and develop effective prevention strategies, ultimately leading to a decrease in SUID. This report is a baseline study to understand the scope of infant death investigations in selected US states. We found that almost all SUID cases had an autopsy (100%) and DSI (98%) performed, but that the components of the investigation varied. The autopsy components conducted least often were blood chemistry (41%) and genetic testing (23%). However, these tests may only be conducted as needed and depending on the circumstances.¹⁵ The perceived usefulness of tests influence actual performance of testing, as highlighted in a recent study about infectious disease testing for SUID.¹⁹ The DSI components conducted least often include usual sleep place (73%) and usual sleep position (63%). Changes in sleep place and position are associated with an increased risk of SIDS,²⁰ making usual sleep place and position important variables to document. However, the variable new or different environment than usual was available for 92% of cases and may be used by death certifiers when usual sleep place and position are unavailable.

Although the performance of a DSI and an autopsy were nearly universal in our study, a marked improvement from earlier decades,¹⁰ we note that there were still some DSI components for which the percentage of performance is not optimal. Any scene re-creation (45%), especially one with a doll (37%), was available for fewer than one-half of cases and can be an integral part in understanding airway obstruction and the role of potential hazards in the sleep environment.^6,15 Additionally, there was a lack of information about the infant’s airway when found, available for 73% of cases, which is also important in understanding the circumstance surrounding the death. This information may be unavailable because parents or emergency medical services personnel move the infant quickly without noting the infant’s position.^15,20

Because the analysis of missing/unknown responses revealed high data quality (ie, few missing and unknown responses), observed variations in reporting performance of DSI and autopsy components between states likely reflect true practice. The data used in these analyses are compiled from various sources, and are not collected through primary data collection. As such, understanding the reasons for the variations in reporting and missing/unknown responses are outside of the scope of these data but could be attributed to a number of factors, for example, differing protocols for autopsies and DSIs, variation in the capacity of the CDR teams collecting and entering data, availability of resources for investigations, and differences in medicolegal systems. Study states represent county coroner systems, county medical examiner systems, regional offices overseen by a state medical examiner, combined county medical examiner and coroner systems, state medical examiner systems, and combined state and county medical examiner systems.²¹ Although slight variation was observed in the percentages of autopsy components reported depending on the type of medicolegal system, this study shows that documenting complete and comprehensive autopsies and DSIs is feasible across all types of systems.

A limitation is that our study only represents 7 states and may lack generalizability to the US as a whole. In addition, we relied on information reported by state and local CDR teams, and data have not been validated. However, it is likely that reported data were accurate because most reported information was based on abstracted and summarized data from several sources and discussions among multidisciplinary professionals who often had first-hand knowledge of the cases. Moreover, our ability to accurately evaluate the completeness of DSI and autopsy components was improved because we created composite variables considering responses to several related questions. Additionally, if there were reporting biases, we would anticipate that DSI and autopsy components were underreported, because it is more likely that a component was conducted and not documented as opposed to documented and not conducted.

Because SUID Case Registry grantees evaluate the gaps in case investigations, they work with CDR teams and medicolegal professionals to implement activities to improve DSI and autopsy consistency and comprehensiveness. For example, some grantees provide resources to medical examiner offices to investigate and review SUID cases. Other grantees facilitate trainings for medical examiners, coroners, and death investigators to emphasize what data are important to document at an infant death scene, how to complete the SUIDIRF or jurisdictional equivalent, and how to perform a scene re-creation using a doll. Grantees have also distributed DSI kits with dolls and cameras for documenting scene re-creations. These tools allow investigators to record the most important information from the death scene, including the infant’s airway when found. Future studies using the SUID Case Registry data could monitor the impact of these activities on progress toward improving practices.

The importance of the DSI and autopsy in determining cause of death is well-established and much work has been done to improve case investigation practices. This study serves as a baseline to understand the scope of infant death investigations in selected states. Standardized and comprehensive DSI and autopsy practices across jurisdictions and states may increase knowledge about SUID etiology and lead to improved understanding of cause-specific SUID risk and protective factors. Additionally, these data, representing a variety of medicolegal systems, demonstrate that documenting complete and comprehensive autopsies and DSIs is feasible across many systems. We encourage pediatricians, forensic pathologists, and other medicolegal experts who review these findings to use them to inform system changes and improvements in DSI and autopsy practices and SUID prevention efforts. To improve practices, the medicolegal community could work to ensure that comprehensive protocols are further developed, such that a gold standard becomes universally accepted and implemented. There is a need to identify DSI and autopsy practices that are most effective and have the strongest influence on explaining why SUID occurs.²² In determining feasibility, one must consider available resources (eg, budget, staffing, equipment, and training needs).²³ Future studies using the SUID Case Registry data can monitor resulting progress in improving standardized practices.