传染病在低感染率状态下大规模人群筛检的假阳性模拟分析  

False positives of screening in large-scale population with low infection rate of an infectious diseasea:a modeling analysis

作　　者：蒋鸿琳 童懿昕 徐宁 周艺彪[1] 姜庆五[1] JIANG Honglin;TONG Yixin;XU Ning;ZHOU Yibiao;JIANG Qingwu(Department of Epidemiology,School of Public Health,Fudan University,Tropical Disease Research Center,Collaborating Center for Tropical Diseases,Shanghai 200032,China)

机构地区：[1]复旦大学公共卫生学院,热带病研究中心,热带病流行病学联合实验室,上海200032

出　　处：《上海预防医学》2022年第4期314-317,共4页Shanghai Journal of Preventive Medicine

摘　　要：【目的】探讨传染病在低感染状态下,大规模人群筛查中筛检试验的阳性预测值(PPV)以及假阳性者数量。【方法】通过数据模拟的方式,假定某人群的总人口为2 000万,人群疾病感染率为0.1%~5.0%,模拟不同灵敏度(99.0%、99.5%、100.0%)和特异度(97.0%、97.5%、98.0%、98.5%、99.0%、99.5%、99.9%)的组合情况,计算各组合的PPV、真阳性数和假阳性数。【结果】在低感染率(≤5.0%)状态下,与灵敏度相比,特异度对PPV的影响更大,且随着感染率的下降,特异度提高时PPV的增幅加大。当感染率>1.0%时,特异度越趋近99.9%,PPV越接近100.0%;而当感染率<1.0%时,PPV的最大值也仅约为90.0%。当人群感染率为0.1%、灵敏度≥99.0%时,在2 000万的人群中筛检试验可以发现的真阳性人数约为2万人;当特异度为97.0%时,假阳性人数约为59.9万人,PPV为3.2%;当特异度达到99.9%时,假阳性人数降到约2万人,PPV升高到50.0%。当人群感染率为1.0%时,灵敏度≥99.0%和特异度≥97.0%的筛检试验在2 000万的人群中可发现的真阳性数为19.8万~20.0万人;当特异度由97.0%升高至99.9%时,假阳性人数由59.4万人降至2万人。当人群感染率为5.0%时,灵敏度≥99.0%和特异度≥97.0%的筛检试验在2 000万的人群中可发现的真阳性数为99.0万~100.0万人;当特异度由97.0%升高至99.9%时,假阳性人数由57.0万人降至1.9万人。在总人口为2 000万的人群中,当感染率≤5.0%时,即使灵敏度和特异度分别达到最大值100.0%和99.9%,仍存在约2万例的假阳性。【结论】当人口数量较多而感染率较低时,运用筛检试验进行大规模人群筛查除了要提高特异度外,大量假阳性所产生的问题不可忽视。[Objective]To explore the positive predictive value(PPV)and false positive(FP)number of screening test in mass testing when the prevalence of infection is low.[Methods]Assuming a population of 20 million with the prevalence of disease infection ranging from 0.1% to 5.0%,PPV,true positive(TP)and FP numbers were calculated under different scenarios of combination of sensitivity(99.0%,99.5%,and 100.0%)with specificity(97.0%,97.5%,98.0%,98.5%,99.0%,99.5%,and 99.9%).[Results]For low infection prevalence(≤5.0%),specificity has a greater impact on PPV than sensitivity;with the decrease of infection prevalence,the increase in PPV elevates when the specificity increases. When the infection prevalence is >1.0%,the closer the specificity is to 99.9%,the closer the PPV is to 100.0%.However,when the infection prevalence is <1.0%,the maximum PPV is only about 90.0%. When the infection rate is 0.1%,a screening test with more than 99.0% sensitivity could detect about 20 thousand TP cases in a population of 20 million. Additionally,the FP and PPV are estimated to be 599 thousand and 3.2% if the specificity is 97.0%,and 20 thousand and 50.0% if the specificity is 99.9%. When the infection rate is 1.0%,a screening test with ≥99.0% sensitivity and ≥97.0% specificity could detect about 0.198-0.200 million TP cases;and the number of FP decreases from 594 thousand to 20 thousand when the specificity increases from 97.0% to 99.9%. When the infection rate is 5.0%,a screening test with ≥99.0% sensitivity and ≥97.0% specificity could detect about 0.99-1.00 million TP cases;and the number of FP decreases from 570 thousand to 19 thousand when the specificity increases from 97.0% to 99.9%. When the infection prevalence is ≤5.0% in a total population of 20 million,there are about 20,000 FP cases even if the sensitivity and specificity reach the maximum values of 100.0% and 99.9%,respectively.[Conclusion]When the population is large and the infection prevalence is low,in addition to improving the specificity of the screening test in

关 键 词：筛检试验 假阳性 阳性预测值 灵敏度 特异度 感染率 

分 类 号：R181.2[医药卫生—流行病学]