Respond
Respond
复制标题
回应
DOI：
--
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. Ardell
中科院分区：
文献类型：
--
作者：
Michael Hass;A. Ardell
我们感谢尼尔斯·凯丁和托马斯·谢克对我们关于生育率时间趋势研究中胎次条件化导致的选择偏倚的文章所作的评论。我们同意，随着时间的推移，在西方国家发生了明显的推迟生育（Keiding和Scheike标记为“幸存者选择”），这是由行为和意志而不是生物因素解释的。然而，推迟生育是一个完全不同的概念，从偏见，由于奇偶条件，我们提出。与行为驱动推迟生育相反，胎次条件偏差是一种设计驱动的选择偏差，具有很强的生物成分和强度，根据抽样框架而变化。胎次条件偏倚背后的关键问题是定义一个研究人群，在一个横截面的时间，限制类的奇偶性，生物生育力的异质性，并在风险周期的差异成功的横截面前的广泛的年龄范围。因此，奇偶条件偏差是一种设计驱动的现象，独立于行为或社会发展。对产次等级的不适当限制可能会导致选择偏差，而推迟生育可能会扭曲对生育力时间趋势的估计。这两种现象在研究生殖力的时间趋势时都应加以考虑。我们以瑞典的研究为例，以证明奇偶条件偏差的可能性。它对合格性的定义如下：“我们的研究人群包括所有年龄在20岁或20岁以上的初产妇女，她们在1983年至2002年期间开始尝试怀孕，随后分娩。192)因此，研究人员在两个横截面的时间进行了限制。特别是，排除了所有在1982年12月31日分娩的妇女，以及那些在随访结束时仍然没有孩子的妇女。Sallmén等人的表2，Sallmén等人的Lexis图表，Keiding和Scheike的1980-2010年丹麦未生育妇女的频率清楚地表明，在一项使用类似抽样框架的研究中，特定年龄组在不同时间段被排除的情况存在差异。在丹麦，从1980年到2010年的不同时间段来看，约有12%至3.6%的20岁女性曾生育过。40岁女性的这一数字约为91%至86%。此外，该表还显示了在绝经前结束随访的研究中将被排除在外的未生育妇女的特定年龄组频率。因此，按胎次分类的限制导致了初次生育年龄随时间推移的任意趋势。在瑞典的研究中，1945年的队列成员应该在37岁或37岁以上生第一个孩子，而1979年的队列成员应该在24岁之前生育。瑞典研究中的排除也与生育力有差异。生育对产次有生物学影响。一旦一个年龄很大的研究人群
We thank niels Keiding and Thomas Scheike for their commentary pertaining to our article on selection bias due to parity-conditioning in studies of time trends in fertility. We agree that a clear postponement of parenthood (labeled “survivor selection” by Keiding and Scheike) has occurred over time in Western countries, and that this is explained by behavioral and volitional rather than biological factors. However, postponement of parenthood is an entirely different concept from the bias due to parity-conditioning that we presented. in contrast to behavior-driven postponement of parenthood, parity-conditioning bias is a design-driven selection bias with a strong biological component and strength that varies according to sampling frame. The key issues behind parity-conditioning bias are the definition of a study population with a wide age range at a cross-section of time, restriction by classes of parity, heterogeneity in biological fertility, and differential success in at-risk cycles before the cross-section. Thus, parity-conditioning bias is a design-driven phenomenon that is independent of behavioral or societal developments. inappropriate restriction on parity classes may cause selection bias, whereas postponement of parenthood may, if anything, distort the estimation of the time trend in fecundity. Both these phenomena should be considered in studies of time trends in fecundity. We took the Swedish study as an example, to demonstrate the potential for parity-conditioning bias. it defined eligibility as follows: “our study population encompasses all primiparous women aged 20 years or older at the time they initiated their pregnancy attempt, who subsequently gave birth from 1983 through 2002.” 192) Thus, the researchers made restrictions due to classes of parity at two cross-sections of time. Specifically, all the women who were parous on december 31, 1982, were excluded, as were those who remained childless at the end of follow-up. Table 2 in Sallmén et al., the Lexis diagrams in Sallmén at al., and Keiding and Scheike’s frequencies of nulliparous women in denmark in 1980–2010 clearly demonstrate the difference in age group-specific exclusions at a cross-section of time in a study using a similar sampling frame. in denmark, about 12% to 3.6% of 20-year-old women were parous at cross-sections of time from 1980 to 2010. The same figures were about 91% to 86% for women aged 40. Moreover, the table shows the age group-specific frequencies of nulliparous women who would be excluded in a study with follow-up ending before menopause. in consequence, restriction by parity classes leads to an arbitrary trend over time in age at first birth. in the Swedish study, the 1945 cohort members should have had their first child at the age of 37 or over to be included, whereas the 1979 cohort members should have reproduced before 24 years old. The exclusions in the Swedish study were also differentially related to fecundity. Fecundity has a biological effect on parity. once a study population with a wide age