A comparison of two methods for calculating expected mortality.
A comparison of two methods for calculating expected mortality.
复制标题
两种计算预期死亡率方法的比较。
DOI:
10.1002/sim.4780040114
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发表时间:
1985
影响因子:
2
通讯作者:
中科院分区:
文献类型:
--
作者:
The authors conclude that the traditional person-years method used in occupational mortality studies cannot be justified. They contend that expected mortality should not take into account the survival experience of the study group. Although this proposal has a certain intuitive appeal, we submit that this approach is inappropriate and that their presentation is inconsistent. Hartz et al. present an alternative method to the person-years method, which they call the ‘prospective’method, and which we will here call the ‘actuarial method’. The proposed actuarial method of calculating expected mortality is simply a sum of individual risks, with risk defined in the usual sense as the conditional probability of dying during the period of study. This method results in a cumulative estimate of expected deaths at the end of follow-up. In this way the expected mortality is a function of the length of the study period. The basis for the person-years method, on the other hand, is the calculation of rates (as opposed to risks) per person-time. This method therefore takes into account instantaneous changes in the survival experience of the study group relative to the standard over the entire period of study. We, along with other commentators, believe that such a method is preferable when examining long-term mortality data. Hartz et al.’s example 3 actually illustrates the problem quite well. In a cohort where all 50 individuals in the study group die in the first year of a 20 year follow-up, use of the actuarial method virtually ignores this unusual situation and results in 16.6 expected deaths. Use of the person-years method, on the other hand, results in an expectation of only one death, compared to the observed value of 50, a result more descriptive of the dramatic excess mortality rate in this example.Inconsistencies in the paper occur with an attempt to explain the differences between the expected mortality calculated according to the two methods. The authors state that the person-years method results in estimates of expected mortality that are ‘too low’when the mortality rates in the study group are less than the standard rates. Actually, in general, the person-years method produces higher expected mortality than the actuarial method when the study group has lower mortality rates compared to the standard population, whereas the reverse is true when the study group has higher mortality rates. The situation becomes more complicated for cause-specific mortality, not considered by Hartz et a/. Their example 2 as well as their calculations from actual data on page 384 illustrate this point.
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DOI:
10.1016/0021-9681(70)90038-x
发表时间:
1970
期刊:
Journal of Chronic Diseases
影响因子:
--
作者:
A. Oleinick;N. Mantel
通讯作者:
N. Mantel
影响因子:
1.9
作者:
M. C. Sheps
通讯作者:
M. C. Sheps
影响因子:
0.8
作者:
N. Breslow
通讯作者:
N. Breslow
DOI:
10.1097/00043764-197603000-00008
发表时间:
1976
期刊:
Journal of occupational medicine. : official publication of the Industrial Medical Association
影响因子:
--
作者:
J. Goldsmith;D. Hirschberg
通讯作者:
D. Hirschberg
DOI:
10.1097/00043764-197603000-00009
发表时间:
1976-01-01
影响因子:
3.2
作者:
MCMICHAEL, AJ
通讯作者:
MCMICHAEL, AJ