Abstract â–¡ 32

Although the incidence of SIDS has fallen recently, it is still a leading cause of post-neonatal death in most developed countries. In Alberta, since 1977, all sudden unexpected deaths (SUD) in infancy are reported to the Office of the Chief Medical Examiner. In all cases there is a scene investigation, autopsy and a review of medical records. We reviewed the files of all SUDs and abstracted information from those confirmed as SIDS. The aim of the study was to determine trends of SIDS death and the impact of SIDS deaths on the total infant death, and to examine the distribution of the risk factors in cases of SIDS over time.

This is a population-based descriptive study, and we identified 1934 cases of SIDS who fit standard criteria. Demographic characteristics of the infants and their mothers, and other associated factors were collected. The incidence was calculated per 1000 live births. The contribution of SIDS to infant mortality were calculated. Univariate analysis was used to test the association between variables.

During the study period between 1977 and 1995, the SIDS incidence in Alberta decreased in male and female infants, particularly since 1992. The rates per 1000 live birth for infants age 4 weeks to 1 year were: 1977, 1.89; 1978, 2.37; 1979, 2.35; 1980, 2.04; 1981, 1.83; 1982, 1.98; 1983, 1.93; 1984, 1.70; 1985, 1.96; 1986, 1.74; 1987, 1.33; 1988, 1.64; 1990, 1.21; 1991, 1.66; 1992, 1.02; 1993, 1.14; 1994, 0.98; 1995, 0.89. The greatest reduction in SIDS incidence was in infants aged 4 to 15 weeks, infants whose mother's age was between 20 and 30 years and non-Native infants. The distribution of associated SIDS factors, such as sleeping position among SIDS cases changed over time. The SIDS incidence in Alberta was higher than that in Canada over the study period, and the proportion of SIDS case among infant deaths was higher in Alberta than in Canada.

Based on ecological analysis, changes in some factors such as a decrease in fertility among young women and maternal smoking, might have contributed to the decrease of SIDS in Alberta. The sharp decrease since 1992 might be due to the intervention program against SIDS initiated in 1991. The difference of incidence between Alberta and Canada is unexplained but might be partly due to a different distribution of some risk factors, less rigorous case definitions in other areas, and different proportions of Native deaths.