背景:诊断测试的准确性取决于其内在特征和疾病发生率。本研究旨在描述肺孢子虫肺炎(PJP)的测试后概率,根据急性呼吸衰竭(ARF)患者的PCR和β-D-葡聚糖(BDG)测试结果。
方法:从文献中提取PCR和BDG的诊断性能。在2243例非HIV免疫受损的ARF患者的数据集中评估了肺孢子菌肺炎的发生率。假设在5000个随机发生率样本中呈正态分布,模拟了肺孢子菌肺炎的发生率。使用贝叶斯定理评估后验概率。
结果:非HIV-ARF患者中PJP的发生率为4.1%(95CI3.3-5)。监督分类确定了4个感兴趣的亚组,发病率从2.0%(无磨玻璃混浊;95CI1.4-2.8)到20.2%(造血细胞移植,磨砂玻璃混浊,无PJP预防;95CI14.1-27.7)。在总人口中,PCR和BDG的阳性检测概率为32.9%(95CI31.1-34.8)和22.8%(95CI21.5-24.3),分别。PCR和BDG的检测后感染的阴性概率为0.10%(95CI0.09-0.11)和0.23%(95CI0.21-0.25),分别。在最高风险亚组中,PCR和BDG的阳性预测值为74.5%(95CI72.0-76.7)和63.8%(95CI60.8-65.8),分别。
结论:尽管两种测试都产生了很高的内在性能,该队列中PJP的低发生率导致试验后阳性概率低.我们提出了一种方法来说明测试前和测试后的概率关系,该方法可以根据预定义临床环境中的疾病发生率来改善临床医生对诊断测试性能的看法。
BACKGROUND: The accuracy of a diagnostic test depends on its intrinsic characteristics and the disease incidence. This study aims to depict post-test probability of Pneumocystis pneumonia (PJP), according to results of PCR and Beta-D-Glucan (BDG) tests in patients with acute respiratory failure (ARF).
METHODS: Diagnostic performance of PCR and BDG was extracted from literature. Incidence of Pneumocystis pneumonia was assessed in a dataset of 2243 non-HIV immunocompromised patients with ARF. Incidence of Pneumocystis pneumonia was simulated assuming a normal distribution in 5000 random incidence samples. Post-test probability was assessed using Bayes theorem.
RESULTS: Incidence of PJP in non-HIV ARF patients was 4.1% (95%CI 3.3-5). Supervised classification identified 4 subgroups of interest with incidence ranging from 2.0% (No ground glass opacities; 95%CI 1.4-2.8) to 20.2% (hematopoietic cell transplantation, ground glass opacities and no PJP prophylaxis; 95%CI 14.1-27.7). In the overall population, positive post-test probability was 32.9% (95%CI 31.1-34.8) and 22.8% (95%CI 21.5-24.3) for PCR and BDG, respectively. Negative post-test probability of being infected was 0.10% (95%CI 0.09-0.11) and 0.23% (95%CI 0.21-0.25) for PCR and BDG, respectively. In the highest risk subgroup, positive predictive value was 74.5% (95%CI 72.0-76.7) and 63.8% (95%CI 60.8-65.8) for PCR and BDG, respectively.
CONCLUSIONS: Although both tests yield a high intrinsic performance, the low incidence of PJP in this cohort resulted in a low positive post-test probability. We propose a method to illustrate pre and post-test probability relationship that may improve clinician perception of diagnostic test performance according to disease incidence in predefined clinical settings.