In this study, we aimed to investigate the performance of nontreponemal antibody tests in cerebrospinal fluid (CSF) specimens from
syphilis patients. From September 2009 to September 2012, CSF specimens were collected at the Shanghai
Skin Disease Hospital in Shanghai, China, from 1,132
syphilis patients without
HIV infection, including 154 with symptomatic and 56 with asymptomatic
neurosyphilis. All of the CSF specimens underwent testing with a rapid plasma
reagin (RPR) test, an
RPR-V (commercial RPR
antigen diluted 1:2 in 10% saline) test, the
toluidine red unheated serum test (TRUST), and the
Venereal Disease Research Laboratory (VDRL) test. Specificities, sensitivities, positive predictive values (PPVs), negative predictive values (NPVs), and kappa values were calculated to determine the performances of the tests. We compared results of the CSF-VDRL, CSF-RPR, CSF-
RPR-V, and CSF-TRUST among patients with symptomatic and asymptomatic
neurosyphilis who had reactive CSF-Treponema pallidum particle agglutination (TPPA) test results. Overall, the CSF-VDRL test was reactive in 261 patients (23.1%). There were no cases in which the CSF-VDRL was nonreactive and CSF-RPR, CSF-
RPR-V, or CSF-TRUST was reactive. Agreement between the results of CSF-TRUST and CSF-RPR was almost perfect (κ=0.861), with substantial agreement between the results of CSF-RPR and CSF-
RPR-V (κ=0.740). The sensitivities of CSF-VDRL, CSF-RPR, CSF-
RPR-V, and CSF-TRUST were 81.4%, 76.2%, 79.5%, and 76.2%, respectively. Compared to CSF-VDRL, CSF-RPR, CSF-
RPR-V, and CSF-TRUST had comparable PPVs and NPVs. However, the specificity of CSF-VDRL (90.3%) was significantly lower than those of the other tests (92.7 to 93.4%). Therefore, CSF-RPR, CSF-
RPR-V, and CSF-TRUST can be considered alternative tests for
neurosyphilis diagnosis in HIV-negative populations, particularly when the CSF-VDRL is not available.