Hong Kong case-control study of sudden unexpected infant death

Aim To document causes of all unexpected child deaths under 2 years of age during a 4-year period (1999-2003), and to identify factors associated with sudden infant death syndrome (SIDS) in Hong Kong. Methods The case-control component of the study compared information from SIDS deaths (n=16) with healthy controls (n=223) identified randomly from all births in Hong Kong. Coroner records of all deaths under 2 years of age were later reviewed. Results SIDS risk factors included prone sleep position, smoking by mother, bedsharing with someone other than the parents, and baby found with head covered. Eighteen deaths were officially classified as SIDS but, on review of the coroner records, there were 33 potential SIDS deaths (many labelled as unascertained/unknown). Conclusion Hong Kong SIDS incidence has fallen from 0.3/1000 (95% CI: 0.18-0.46 in 1987) to 0.16/1000 (95% CI: 0.11-0.22 in 1999-2002). Despite the small number of cases, key SIDS risk factors are shown to be important in this population. Hong Kong needs to take steps to standardise the investigation and management of these deaths and to establish a child mortality review mechanism to provide feedback to the public, to the health authorities, and to health professionals. Sudden infant death syndrome (SIDS) was originally defined as the sudden death of an infant or young child, which is unexpected by history, and in which a thorough postmortem examination fails to demonstrate an adequate cause of death. 1 Other definitions have been suggested, 2 and recently a new definitional and diagnostic approach has been proposed. 3