Evaluating sudden infant death classification and capturing all deaths with sleep-related factors (SRF): Results from NYC

Background: Sudden and unexpected infant deaths are largely preventable and of public health importance. Classifying these deaths is challenging and varies across jurisdictions; with certification including unintentional injury (asphyxia), SIDS or undetermined.

Objective: Investigate sudden infant death certification protocols in NYC; describe how unsafe sleeping environments (bedsharing, sleeping prone) contributed to these deaths; demonstrate how all deaths with sleep-related factors (SRF) were captured.

Methods: To examine the diagnostic shift in classification, death rates for SIDS and injury over 1996-2006 were compared. In-depth analysis of medical examiner data for unintentional injury and undetermined deaths, 2000-2003, was conducted to better understand the role of SRFs. SIDS, no longer certified in NYC if events such as SRFs are present, was excluded.

Results: Between 1996-2006, SIDS mortality rates declined by 84% (50.4 to 8.0/100,000 live births) and increased 93% for injury (26.8 to 51.8/100,000). This shift was due in part to improved death scene investigations and standardized certification definitions in NYC. 71% of the unintentional asphyxia and undetermined deaths, 2000-2003, had SRFs (death rate: 17.9/100,000). By analyzing the undetermined category, and not just asphyxia deaths, the number of SRF deaths increased three-fold. Black infants and infants born to mothers under 20 had higher SRF death rates, 40.7/100,000 and 61.1/100,000, respectively. Bedsharing was the most common SRF (65%); 75% of non-bedsharing infants were found prone.

Conclusions: To advance the study of SRF deaths and promote consistency in the literature, researchers must identify local certification protocols and develop standard criteria for categorizing infant deaths.