In testing CSF for neurosyphilis, how useful are VDRL and FTA-ABS?

Bottom line:  CSF VDRL is routinely ordered for diagnosis of neurosyphilis and is highly specific yet less sensitive.  If clinical suspicion remains elevated in a negative CSF VDRL, testing with CSF FTA-ABS should be considered as the sensitivity is nearly 100% with a high negative predictive value for ruling out neurosyphilis.

SummaryDynaMed references the CDC guidelines for diagnosing neurosyphilis, which reports that VDRL is very specific, but sensitivity has been reported 20-70%.  VDRL is used as a reference standard for neurosyphilis in many diagnosis cohort studies.

Dumaresq J, et al.  Clinical prediction and diagnosis of neurosyphilis in HIV-infected patients with early syphilis.  J Clin Microbiology.  2013; 51(12): 4060-4066.  Retrospective study of 122 patients with documented HIV infection and early syphilis who were tested for neurosyphilis.  The reference standard was a positive CSF VDRL test and/or white blood cell count >20 cells/µl.  Sensitivity of CSF FTA-ABS was 100% and specificity was 12%.  Negative predictive value was 100%.

Harding AS, et al.  The performance of cerebrospinal fluid treponemal-specific antibody tests in neorsyphilis: a systematic review.  Sex Transm Dis.  2012 Apr; 39(4): 291-7.
The authors identified 3 studies that evaluated CSF FTA-ABS and used CSF VDRL as the reference standard.  The three studies had patient populations (includes HIV positive and negative) of 597 (16% of patients had NS), 27 (42% of patients had NS), and 54 (13% of patients had NS and another 39% had syphilis but not NS).  Sensitivity of CSF FTA-ABS was 100% in all three studies and specificity was 68-100%.  Negative predictive value was 100%.

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About Amy

Clinical Informationist at EUH Branch Library
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