Studiedienst van de Vlaamse Regering (SVR) [Study Centre of the Government of Flanders], Vlaamse overheid [Flemish authorities], Boudewijnlaan, 30, 1000 Brussels, Belgium.
Arch Public Health. 2012 Mar 30;70(1):6. doi: 10.1186/0778-7367-70-6.
When calculating life expectancy, it is usually assumed that deaths are uniformly distributed within each of the age intervals. As most of the infant deaths are neonatal deaths, this calls for a better assessment for that age group.
The Flemish unified death and birth certificates database for all calendar years between 1999 and 2008 was used. A Kaplan-Meier survival analysis on a yearly basis was performed to assess the mean time-to-event and to compare survival curves between both genders.
Over the last years, a slight though not steady decrease of the infant mortality rate is observed. In 2008, the probability among live births of dying before their first anniversary is 4.6‰ in boys and 3.5‰ in girls. The large majority (about 85%) of these have died in their year of birth. The mean survival time of deaths in their year of birth was found to centre around 1 month (about 30 days), which results in a 'mean proportion of the calendar year lived' (k1) close to 0.09. Among those who died in the year after their year of birth yet before their first anniversary, no such concentration in time of the deaths is observed. Differences between the gender groups are small and generally not statistically significant.
Statistics Belgium, the federal statistics office, imputes a value for k1 equal to 0.1 for infant deaths in their year of birth when calculating life expectancy. Our data fully support this value. We think such refinement is generally feasible in calculating life expectancy.
在计算预期寿命时，通常假设死亡在每个年龄区间内均匀分布。由于大多数婴儿死亡都是新生儿死亡，因此需要对该年龄组进行更好的评估。
使用了 1999 年至 2008 年所有历年的佛兰德统一死亡和出生证书数据库。对每年进行 Kaplan-Meier 生存分析，以评估平均时间到事件，并比较两性之间的生存曲线。
在过去几年中，婴儿死亡率略有下降，但并不稳定。2008 年，活产儿在一岁生日前死亡的概率男孩为 4.6‰，女孩为 3.5‰。这些婴儿中的绝大多数（约 85%）在出生当年死亡。在出生当年死亡的婴儿的平均生存时间集中在 1 个月左右（约 30 天），这导致“日历年内生存的平均比例”（k1）接近 0.09。在那些在出生后的第一年死亡的婴儿中，没有观察到死亡时间的这种集中。性别组之间的差异很小，通常不具有统计学意义。
联邦统计局比利时统计局在计算预期寿命时，对出生当年的婴儿死亡事件的 k1 值估计为 0.1。我们的数据完全支持这个值。我们认为，在计算预期寿命时，这种细化通常是可行的。
