Stallard Eric
Research Professor and Co-Director of the Bio demography of Aging Research Unit at the Social Science Research Institute, Duke University, Durham, NC 27708 USA.
N Am Actuar J. 2016;20(4):341-354. doi: 10.1080/10920277.2016.1227269. Epub 2016 Oct 4.
Compression of morbidity is a reduction over time in the total lifetime days of chronic disability, reflecting a balance between (1) morbidity incidence rates and (2) case-continuance rates-generated by case-fatality and case-recovery rates. Chronic disability includes limitations in activities of daily living and cognitive impairment, which can be covered by long-term care insurance. Morbidity improvement can lead to a compression of morbidity if the reductions in age-specific prevalence rates are sufficiently large to overcome the increases in lifetime disability due to concurrent mortality improvements and progressively higher disability prevalence rates with increasing age. Compression of mortality is a reduction over time in the variance of age at death. Such reductions are generally accompanied by increases in the mean age at death; otherwise, for the variances to decrease, the death rates above the mean age at death would need to increase, and this has rarely been the case. Mortality improvement is a reduction over time in the age-specific death rates and a corresponding increase in the cumulative survival probabilities and age-specific residual life expectancies. Mortality improvement does not necessarily imply concurrent compression of mortality. This paper reviews these concepts, describes how they are related, shows how they apply to changes in mortality over the past century and to changes in morbidity over the past 30 years, and discusses their implications for future changes in the United States. The major findings of the empirical analyses are the substantial slowdowns in the degree of mortality compression over the past half century and the unexpectedly large degree of morbidity compression that occurred over the morbidity/disability study period 1984-2004; evidence from other published sources suggests that morbidity compression may be continuing.
发病压缩是指慢性残疾的终生天数随时间减少，反映了（1）发病率与（2）由病死率和病愈率产生的病例持续率之间的平衡。慢性残疾包括日常生活活动受限和认知障碍，这些可由长期护理保险承保。如果特定年龄患病率的降低幅度足够大，足以克服因同期死亡率改善以及随着年龄增长残疾患病率逐渐上升而导致的终生残疾增加，那么发病改善就会导致发病压缩。死亡压缩是指死亡年龄方差随时间减少。这种减少通常伴随着平均死亡年龄的增加；否则，为了使方差减小，高于平均死亡年龄的死亡率就需要上升，而这种情况很少出现。死亡率改善是指特定年龄死亡率随时间降低，以及累积生存概率和特定年龄剩余预期寿命相应增加。死亡率改善并不一定意味着同时出现死亡压缩。本文回顾了这些概念，描述了它们之间的关系，展示了它们如何应用于过去一个世纪的死亡率变化以及过去30年的发病率变化，并讨论了它们对美国未来变化的影响。实证分析的主要发现是，在过去半个世纪中，死亡压缩程度大幅放缓，以及在1984 - 2004年发病/残疾研究期间出现了出人意料的大幅发病压缩；其他已发表资料的证据表明发病压缩可能仍在继续。
