National mortality statistics commonly provide disease-specific absolute and relative frequencies of death by sex and age, but not by exposure status. However, it is often of interest to know how many of the diseased individuals, that is the cases, were exposed or not exposed to a specific risk factor. We present two methods to estimate the proportion and the number of exposed and nonexposed cases, both of which require an estimate of the exposure prevalence in the nondiseased population. Method I additionally requires an estimate of the relative effect of exposure, that is a relative risk function if the exposure has a continuous distribution, or a relative risk estimate for each category if the exposure is categorical. Method II additionally requires an estimate of the disease rate among the nonexposed. We provide theoretical justifications, discuss practical limitations, and provide an R script to calculate the probability for nonexposure among the diseased, and compare the approaches. Both methods are subsequently applied to the estimation of the number of never smokers among lung cancer deaths. The two suggested methods rely on the availability of specific data sources and might therefore be applicable in different research settings. Both methods yield unbiased estimates of the number of nonexposed cases, given that the respective underlying assumptions are fulfilled.

中文翻译：

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估计人群中未暴露病例的比例和数量的方法

国家死亡率统计数据通常提供按性别和年龄划分的特定疾病的绝对和相对死亡频率，但不提供暴露状态。然而，了解有多少患病个体（即病例）暴露于或未暴露于特定风险因素通常很有趣。我们提出了两种方法来估计暴露和非暴露病例的比例和数量，这两种方法都需要估计未患病人群中的暴露流行率。方法 I 还需要估计暴露的相对影响，如果暴露具有连续分布，则为相对风险函数，如果暴露是分类的，则需要对每个类别进行相对风险估计。方法 II 还需要估计未接触者的发病率。我们提供理论依据，讨论实际限制，并提供 R 脚本来计算患病者未暴露的概率，并比较这些方法。随后将这两种方法应用于估计肺癌死亡中从不吸烟的人数。这两种建议的方法依赖于特定数据源的可用性，因此可能适用于不同的研究环境。鉴于满足各自的基本假设，这两种方法都会对未暴露病例的数量进行无偏估计。这两种建议的方法依赖于特定数据源的可用性，因此可能适用于不同的研究环境。鉴于满足各自的基本假设，这两种方法都会对未暴露病例的数量进行无偏估计。这两种建议的方法依赖于特定数据源的可用性，因此可能适用于不同的研究环境。鉴于满足各自的基本假设，这两种方法都会对未暴露病例的数量进行无偏估计。