论文标题
关于筛查悖论的形式主义
On the Formalism of The Screening Paradox
论文作者
论文摘要
贝叶斯定理通过将测试的预测价值与疾病患病率联系起来,对筛查测试的准确性施加了不可避免的限制。上述限制独立于测试的充分性和构成,因此暗示了对筛查过程本身的固有限制。根据WHO的$ Wilson-Jungner $标准,进行筛查之前的先决条件之一是确保存在对筛查状况的治疗。但是,随之而来的是悖论,随之而来的是筛选悖论。如果筛选疾病过程并随后进行治疗,则其流行率将下降,根据贝叶斯定理,这将使测试的预测价值下降以回报。换句话说,通过在开发要完成的任务中执行和成功,一项非常有力的筛选测试将矛盾地降低其正确识别未来筛查疾病的人的能力。其中$ j $是Youden的统计数据(敏感性[$ a $] +特异性[$ b $] - 1),而$ ϕ $是普遍性,随后的$ k $,$ k $,$ρ(ϕ__ {k})$的积极预测值的比率比原始$ρ(ϕ_ {0}) $ζ(ϕ_ {0},k)= \ frac {ρ(ϕ_ {k})}} {ρ(ϕ__ {0})} = \ frac {ϕ_k(1-b)+jx_0_k} 在此手稿中,我们探索了数学模型,该模型正式化了所述筛选悖论并探索其对人口级筛查计划的影响。特别是,我们定义了逆转悖论的效果所需的阳性测试迭代次数(PTI)如下: 美元 其中$ω$是阳性似然比(LR+)的平方根。
Bayes' Theorem imposes inevitable limitations on the accuracy of screening tests by tying the test's predictive value to the disease prevalence. The aforementioned limitation is independent of the adequacy and make-up of the test and thus implies inherent Bayesian limitations to the screening process itself. As per the WHO's $Wilson-Jungner$ criteria, one of the prerequisite steps before undertaking screening is to ensure that a treatment for the condition screened exists. However, in so doing, a paradox, henceforth termed the screening paradox, ensues. If a disease process is screened for and subsequently treated, its prevalence would drop in the population, which as per Bayes' theorem, would make the tests' predictive value drop in return. Put another way, a very powerful screening test would, by performing and succeeding at the very task it was developed to do, paradoxically reduce its ability to correctly identify individuals with the disease it screens for in the future. Where $J$ is Youden's statistic (sensitivity [$a$] + specificity [$b$] - 1), and $ϕ$ is the prevalence, the ratio of positive predictive values at subsequent time $k$, $ρ(ϕ_{k})$, over the original $ρ(ϕ_{0})$ at $t_0$ is given by: $ζ(ϕ_{0},k) = \frac{ρ(ϕ_{k})}{ρ(ϕ_{0})} =\frac{ϕ_k(1-b)+Jϕ_0ϕ_k}{ϕ_0(1-b)+Jϕ_0ϕ_k}$ In this manuscript, we explore the mathematical model which formalizes said screening paradox and explore its implications for population level screening programs. In particular, we define the number of positive test iterations (PTI) needed to reverse the effects of the paradox as follows: $n_{iϕ_e}=\left\lceil\frac{ln\left[\frac{ωϕ_eϕ_k-ωϕ_e}{ωϕ_eϕ_k-ϕ_k}\right]}{2lnω}\right\rceil$ where $ω$ is the square root of the positive likelihood ratio (LR+).