Epidemiological changes and causes of sudden unexpected death in infancy: A 30-year population-based study in Basque Country

Introduction

Sudden unexpected deaths in infancy (SUDI) represents a serious public health problem. The objective of this work is to analyze its epidemiological and clinical-pathological characteristics.

Method

Retrospective population study of SUDI in Bizkaia between 1991-2020. Data from the Mortality Registry and Forensic Pathology Service were examined.

Results

1,109 deaths in children under one year were recorded. A forensic autopsy was performed in 107: 61 cases of sudden infant death syndrome (SIDS) and 23 SUDI of explained cause. In other 10 cases SIDS was coded as cause of death without forensic autopsy. The incidence of SIDS was 0.26/1,000/year and decreased from 0.74 (1991-1995 five-year period) to 0.07 (2011-15 and 2016-20 periods). The percentage of SIDS in relation to total mortality decreased from 11.2 to 2.5%. In SIDS, category IB from San Diego (67%) and infants between 1 and 4 months (63%) predominated. An “unsafe sleep environment” was detected in 6 SIDS. 56.5% of the explained SUDI were infectious. Of the 84 autopsied SUDI cases, 70% had no pre-existing disease and 15% were premature and/or low birth weight infants. In 32% there were prodromal symptoms, mainly respiratory tract infection. Microscopic findings suggestive of respiratory infection were diagnosed in 10 SIDS.

Conclusions

The incidence of SIDS in Bizkaia is low and has decreased notably in the last 30 years. Prodromal symptoms and histopathological signs suggestive of infection are relatively common. Forensic studies provide relevant data, although prospective multidisciplinary and multicenter research would be desirable.