Sudden unexpected deaths in infancy: What are the causes?

Objectives: To determine the incidence of various causes of sudden unexpect ed death (SUD) within an entire population and to assess the relative impor tance of an expert autopsy, as well as age of demise, in predicting the lik elihood of finding a cause of death. Methods: We reviewed all cases of SUD in infants aged 1 week to 18 months t hat occurred in the province of Quebec (Canada) between 1987 and 1996. Results: We identified 623 cases of SUD; in 80% the diagnosis was sudden in fant death syndrome (SIDS). Infection was the most common non-SIDS diagnosi s (7.1% of all SUDs), followed by cardiovascular anomalies (2.7%), child ab use or negligence (2.6%), and metabolic or genetic disorders (2.1%). The pe rcentage of non-SIDS deaths was much higher for autopsies performed in cent ers with expertise in pediatric pathology (18% vs 6%, P < .005). The likeli hood of a non-SIDS diagnosis was much higher at age ranges atypical, as com pared with typical, for SIDS (33% at 7 to 27 days, 19% at 6 to 12 months, a nd 64% at 12 to 18 months [atypical] vs 15% at 1 to 6 months [typical]; P = .003). Conclusion: The study of an entire population provides more reliable data r egarding causes of SUDs than does the study of small groups. We recommend t hat in addition to a thorough investigation of each SUD, autopsies be perfo rmed in centers with expertise in pediatric pathology. This recommendation takes on added significance in this era of decreasing SIDS rates.