de Beer Joop, Janssen Fanny
Netherlands Interdisciplinary Demographic Institute/University of Groningen, PO Box 11650, The Hague, 2502 AR, The Netherlands.
Population Research Centre, Faculty of Spatial Sciences, The Netherlands & Netherlands Interdisciplinary Demographic Institute, University of Groningen, The Hague, The Netherlands.
Popul Health Metr. 2016 Dec 1;14:46. doi: 10.1186/s12963-016-0113-1.
A decrease in mortality across all ages causes a shift of the age pattern of mortality, or mortality delay, while differences in the rate of decrease across ages cause a change in the shape of the age-at-death distribution, mortality compression or expansion. Evidence exists for both compression and delay of mortality. Existing parametric models to describe the full age pattern of mortality are not able to capture mortality delay versus mortality compression. More recent models that assess delay versus compression mostly focused on the adult or old ages alone and did not distinguish mortality compression below and above the modal age at death, although they represent different mechanisms.
This paper presents a new parametric model that describes the full age pattern of mortality and assesses compression - at different stages of life - and delay of mortality: the CoDe model. The model includes 10 parameters, of which five are constant over time. The five time-varying parameters reflect delay of mortality and compression of mortality in infancy, adolescence, young adulthood, late adulthood, and old age. The model describes infant and background mortality by two simple functions, uses a mixed logistic model with different slopes in adult, middle, and old age, and includes the modal age at death as a parameter to account for the delay in mortality.
Applying the CoDe model to age-specific probabilities of death for Japanese, French, American, and Danish men and women between 1950 and 2010 showed a very good fit of the full age pattern of mortality. Delay of mortality explained about two-thirds of the increase in life expectancy at birth, whereas compression of mortality due to mortality declines in young age explained about one-third. No strong compression of mortality in late adulthood age was observed. Mortality compression in old age has had a small negative impact on life expectancy.
The CoDe model proved a valid instrument for describing the full age pattern of mortality and for disentangling the effects of mortality delay and compression - at different stages of life - on the increase in life expectancy.
各年龄段死亡率的下降会导致死亡年龄模式的转变，即死亡延迟，而不同年龄段下降速率的差异会导致死亡年龄分布形状的变化，即死亡压缩或扩张。有证据表明存在死亡压缩和死亡延迟现象。现有的用于描述完整死亡年龄模式的参数模型无法捕捉死亡延迟与死亡压缩。最近评估延迟与压缩的模型大多仅关注成年人或老年人，且未区分死亡众数年龄以下和以上的死亡压缩情况，尽管它们代表不同的机制。
本文提出了一种新的参数模型，即CoDe模型，该模型描述完整的死亡年龄模式，并评估不同生命阶段的死亡压缩和死亡延迟。该模型包含10个参数，其中5个随时间保持不变。5个随时间变化的参数反映婴儿期、青春期、青年期、成年后期和老年期的死亡延迟和死亡压缩情况。该模型通过两个简单函数描述婴儿死亡率和背景死亡率，在成年、中年和老年阶段使用具有不同斜率的混合逻辑模型，并将死亡众数年龄作为一个参数来解释死亡延迟。
将CoDe模型应用于1950年至2010年间日本、法国、美国和丹麦男性和女性的年龄别死亡概率，结果显示该模型对完整的死亡年龄模式拟合得非常好。死亡延迟解释了出生时预期寿命增加的约三分之二，而年轻时死亡率下降导致的死亡压缩解释了约三分之一。在成年后期未观察到强烈的死亡压缩现象。老年期的死亡压缩对预期寿命有较小的负面影响。
CoDe模型被证明是一种有效的工具，可用于描述完整的死亡年龄模式，并区分不同生命阶段的死亡延迟和死亡压缩对预期寿命增加的影响。
