Comparison of the CSF-TRUST and CSF-RPR with the CSF-VDRL for the Diagnosis of Neurosyphilis among HIV-negative Syphilis Patients in China.
This study aimed to investigate the performance of the nontreponemal antibody tests in cerebrospinal fluid (CSF) specimens from syphilis patients. From September 2009 to September 2012, CSF were collected from 1132 syphilis patients without HIV infection, including 154 with symptomatic and 56 with asymptomatic neurosyphilis from the Shanghai Skin Disease Hospital in Shanghai, China. All the CSF underwent testing with the rapid plasma reagin (RPR), RPR-V (diluted commercial RPR antigen 1:2 in 10% saline), toluidine red unheated serum test (TRUST) and venereal disease research laboratory (VDRL) test. Specificities, sensitivities, positive predictive values (PPV), negative predictive values (NPV) and kappa values were calculated to determine test performance. We compared results of CSF-VDRL, CSF-RPR, CSF-RPR-V and CSF-TRUST among patients with symptomatic and asymptomatic neurosyphilis who had reactive CSF-T. pallidum particle agglutination (TPPA) tests.Overall, the CSF-VDRL test was reactive in 261 patients (23.1%). There were no cases in which 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 (?=0.861), with substantial agreement between the results of CSF-RPR and CSF-RPR-V (?=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, the 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 that of the other tests (92.7-93.4%). Therefore, the CSF RPR, CSF-RPR-V and CSF-TRUST can be considered as alternative tests for neurosyphilis diagnosis in HIV-negative populations, particularly when the CSF-VDRL is not available.