A comparison of nontreponemal tests in cerebrospinal fluid for neurosyphilis diagnosis: equivalent detection of specific antibodies

ABSTRACT Syphilis is a re-emerging sexually-transmitted infection, caused by the spirochete Treponema pallidum, that may penetrate early into the central nervous system. The venereal disease research laboratory test (VDRL) on the cerebrospinal fluid (CSF) is the most widely used for neurosyphilis diagnosis. We evaluated the performance of two other nontreponemal tests (rapid plasma reagin [RPR] and unheated serum reagin [USR] tests) in comparison with the VDRL in CSF. Methods: We analyzed CSF samples from 120 individuals based on VDRL reactivity in the CSF and the clinical picture of neurosyphilis. Results: High inter-rater reliability was found among all three tests, with equivalent sensitivity and specificity. Intraclass correlation coefficient for absolute agreement was 1 for VDRL versus USR, 0.99 for VDRL versus RPR, and 0.99 for RPR versus USR. Conclusions: Rapid plasma reagin and unheated serum reagin tests were identified as excellent alternatives for neurosyphilis diagnosis.

摘要
梅毒是一种复发性性传播感染，由梅毒螺旋体（Treponema pallidum）引起，可在早期侵入中枢神经系统。脑脊液（cerebrospinal fluid, CSF）性病研究实验室试验（venereal disease research laboratory test, VDRL）是目前神经梅毒诊断中应用最广泛的检测方法。本研究评估了另外两种非密螺旋体试验——快速血浆反应素试验（rapid plasma reagin, RPR）与不加热血清反应素试验（unheated serum reagin, USR）——相较于脑脊液VDRL试验的检测性能。
方法：本研究基于脑脊液VDRL反应性及神经梅毒的临床表现，对120名受试者的脑脊液样本进行了分析。
结果：三项检测的组间信度均较高，灵敏度与特异度相当。用于评估绝对一致性的组内相关系数（intraclass correlation coefficient, ICC）为：VDRL与USR对比为1，VDRL与RPR对比为0.99，RPR与USR对比为0.99。
结论：快速血浆反应素试验（RPR）与不加热血清反应素试验（USR）可作为神经梅毒诊断的优质替代检测方案。