POST-NEONATAL SUDDEN UNEXPLAINED DEATH IN CALIFORNIA: A COHORT STUDY1

Abstract

Kraus, J. F., and N. O. Borhani (Dept. Community Hlth., Sch. Med., Univ. Calif., Davis, Calif. 95616). Post-neonatal sudden unexplained death in California: a cohort study. Am J Epidemiol 95: 497–510, 1972.—This paper presents some of the initial findings of a study on the incidence of post-neonatal sudden unexplained death. The methods of study included the development of broad criteria for screening death certificates; development of a list of suspected deaths; confirmation of deaths by coroner-medical examiners in California; classification of cases; comparison of diagnostic verification according to cause and place of death; and cohort analysis of the data according to relevant factors antecedent to death. Among the 1968 California live birth cohort (a total of 339,221), 719 infants died according to the screening criteria during the post-neonatal period. Of these, 75.9% were confirmed as post-neonatal sudden unexplained death. The rate of sudden post-neonatal death is 1.55 per 1,000 live births, with a peak rate between one and three months and a seasonal distribution of high rates in the early winter. The death rate is higher for black and American Indian infants than for whites, and higher among male infants than female infants. However, the excess in male-to-female death rate observed in California is not consistent among all races. Death rates are high among infants born of plural births, those born to mothers less than 20 years of age, and those with low birth weight. Other factors associated with post-neonatal sudden unexplained death are duration of prenatal care, legitimacy of birth and occupation of father. Finally, among all causes of dath assignments, the categories of “ill-defined,” “unknown,” interstitial pneumonitis or thymic hyperplasia are most likely to be classified later as sudden unexplained death as compared with the other common causes recorded such as bronchopneumonia, pulmonary congestion or edema.