The purpose of the study is to be used for the study and policy program related to improving infant health by analyzing and assessing the characteristics of the determinants that affect survival period of infant deaths.
The data used in this study are the secondary data from "The study of infant deaths, 1996" conducted by the Ministry of Health and Welfare and the Korean Institute of Health and Social Affairs. The total cases were 5,371. As a dependent variable, survival period(day) was selected and as predicted variables, sex, mother age, birth weight, gestation, parity, delivery method, death site, birth order and congenital malformation were selected.
The analysis method was log-rank test after applying Kaplan-Meier method for preliminary examination. Also, the survival analysis of Cox´s proportional hazards regression model was carried out for multivariate analysis.
The findings of the study are as follows;
First, the cases of infant deaths, which have longer survival period, are apt to be of the unknown cause. It was also showed that the death of the infants who died in less than 1 month was caused mostly by preterm infants or immaturity such as respiratory distress of newborn and disorders related to the length of gestation and fetal growth, while that in 1 month or more was by either congenital malformation of heart or other symptoms and signs that ranked first and second through overall period respectively. SIDS(Sudden Infant Death Syndrome) was placed within the fifth ranks in the cases in less than 6 months. So was other disease of nervous system except meningitis and pneumonia in 6 months or more.
Second, according to the findings of the survival analysis by Kaplan-Meier method, the Median survival time of infant deaths was 20.0 days and 95% confidence interval(CI) was 18-23. All the variables except sex, mother age and birth order were significant in survival analysis.
Third, for the survival analysis with Cox´s model, total missing values were more than 50%. Therefore, the congenital malformation variable which had the most missing values and the birth order─highly correlated with mother age and insignificant in univariate analysis ─ were excluded. Sex and mother age were not significant variables. The risk ratios for birth weight and gestation were declined as the size and length of those were increased. For delivery method, the risk ratio of vaginal delivery was significantly higher than that of Caesarean section. For death site, the risk ratios of the hospital and of one´s house were significantly higher than that of other sites.
Fourth, in the cases of birth weight, gestation and parity, the relation between the cause and the result of survival analysis is explicit, but in the cases of delivery method and death site, it is difficult to identify the cause affecting survival period.
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