Epidemiology of sudden unexpected death in infancy in Argentina: secular trend and spatial variation.

Introduction: Infant mortality comprises deaths among infants younger than one year old. The proportion of sudden unexpected death in infancy (SUDI) varies by country and based on the cause of death.

Objective: To describe the spatial and temporal variation of SUDI in Argentina between 1991 and 2014 according to the International Classification of Diseases, tenth revision. Materials and

Methods: Based on infant death data (provided by the Health Statistics and Information Department), we estimated the percentage of SUDI over the total number of infant deaths and the frequency of causes of death at a provincial, regional, and national level. The risk for death and the secular trend were estimated using a Poisson regression. The SaTScan software, v9.1.1, was used to detect clusters of districts where the percentage of SUDI was significantly different from the national percentage.

Results: In Argentina, between 1991 and 2014, 267 552 infants younger than 1 year died; 7 % corresponded to SUDI; the secular trend of causes was negative and statistically significant; the risk for SUDI was 0.86, and a great spatial heterogeneity was observed. At a national level, the most common cause was sudden infant death syndrome, with inter-regional differences. In nine district clusters, the risk for SUDI ranged between 4.36 and 1.24, which is significantly different from the rest of the country.

Conclusions: The proportion of SUDI and its causes show inter-regional heterogeneity; codes related to inaccurate diagnoses predominated in more unfavorable regions, while sudden infant death syndrome was prevalent in the more developed regions.