From the Division of Infectious Diseases, Department of Medicine.
School of Public Health, University of Alabama at Birmingham, Birmingham, AL.
Sex Transm Dis. 2021 Sep 1;48(9):675-679. doi: 10.1097/OLQ.0000000000001386.
The reverse algorithm for syphilis diagnosis consists of a treponemal antibody screening immunoassay followed by confirmatory nontreponemal antibody testing. It is increasingly used in the United States despite studies suggesting limited cost-effectiveness in high-prevalence groups.
In this retrospective cross-sectional study, we included men who have sex with men tested with the reverse algorithm in an Alabama HIV clinic between March 2015 and February 2017. Trep-Sure enzyme immunoassay (EIA) was used for the initial screen, followed by reflex nontreponemal reactive rapid plasma reagin (RPR) testing of specimens with positive results. Sociodemographic and clinical data were extracted from the electronic medical record and stratified according to EIA screen positivity. Quantitative EIA antibody index values were collected to assess test performance at various thresholds.
Among 1693 men tested for syphilis with the reverse algorithm in HIV clinic, 808 (48%) had a positive initial EIA screen. A majority (53%) of men with subsequent RPR testing had a nonreactive RPR (EIA+/RPR-), and 19% (19/98) of these EIA+/RPR- samples tested had a negative confirmatory Treponema pallidum particle agglutination testing result. Analysis of quantitative EIA index values using a receiver operating characteristics curve suggested that a threshold >8 (rather the current threshold of antibody index 1.2) improved the performance of the test.
Among men who have sex with men tested in HIV clinic, the syphilis reverse algorithm was inefficient because of high rates of prior syphilis and false-positive EIA screening. Frequent syphilis screening in high-prevalence populations is an important part of the US epidemic response, and the traditional algorithm is preferred.
梅毒反向诊断算法包括梅毒螺旋体抗体筛查免疫测定，然后是确证非梅毒螺旋体抗体检测。尽管有研究表明在高流行人群中其成本效益有限，但它在美国的使用越来越多。
在这项回顾性横断面研究中，我们纳入了 2015 年 3 月至 2017 年 2 月在阿拉巴马州艾滋病诊所接受反向算法检测的男男性行为者。Trep-Sure 酶免疫分析（EIA）用于初始筛查，然后对阳性结果的标本进行非梅毒螺旋体反应性快速血浆反应素（RPR）检测。从电子病历中提取社会人口统计学和临床数据，并根据 EIA 筛查阳性结果进行分层。收集定量 EIA 抗体指数值，以评估在不同阈值下的检测性能。
在艾滋病诊所接受反向算法检测的 1693 名男性中，808 名（48%）EIA 筛查阳性。随后进行 RPR 检测的大多数男性（53%）RPR 非反应（EIA+/RPR-），其中 19%（19/98）EIA+/RPR-样本的确证梅毒螺旋体颗粒凝集试验结果为阴性。使用受试者工作特征曲线分析定量 EIA 指数值表明，阈值>8（而不是当前的抗体指数 1.2 阈值）可以提高检测性能。
在接受艾滋病诊所检测的男男性行为者中，梅毒反向算法效率低下，原因是既往梅毒感染率和 EIA 筛查假阳性率高。在高流行人群中频繁进行梅毒筛查是美国疫情应对的重要组成部分，因此首选传统算法。
