Characteristics of the included studies
| Study | Year | Country | Study design | Sample size | Diagnostic criteria of neurosyphilis | HIV status | CSF CXCL13 cut-off (pg/mL) |
| Yang et al 14 | 2022 | China | Prospective | 75 (57 syphilis and 18 neurosyphilis) | Included a diagnosis of syphilis and with one of the following three conditions: (1) presence of neurological symptoms or signs and positive CSF-TPPA; (2) presence of neurological symptoms or signs and CSF protein >450 mg/L and CSF nucleated cell count >5/µL without other known causes; (3) absence of neurological symptoms or signs and a positive CSF-TPPA and CSF protein >450 mg/L and CSF nucleated cell count >5/µL without other known causes. | Negative | 57.85 |
| Marra15 | 2021 | USA | Retrospective | 379 (316 syphilis and 63 asymptomatic syphilitic meningitis) | No neurological symptoms and with CSF WBCs >10/μL | 587 participants were positive | 66.7 |
| 379 (350 syphilis and 29 symptomatic syphilitic meningitis) | As neurological symptoms, including new vision loss and hearing loss, and CSF WBCs >10/μL | 182.4 | |||||
| Li et al 18 | 2021 | China | Retrospective | 116 (72 syphilis and 44 neurosyphilis) | Patients with syphilis with all of the following: (1) elevated CSF protein (>500 mg/L) and/or leucocyte count (≥0.01×109/L) in the absence of other known causes of these abnormalities and (2) clinical symptoms or signs consistent with neurosyphilis without other known causes for these clinical abnormalities and (3) with reactive CSF-VDRL and/or CSF-TRUST | Negative | 13.37 |
| Zeng et al 19 | 2016 | China | Retrospective | 71 (31 syphilis and 40 neurosyphilis) | Included positive serologies and 1 or more of the following: (a) positive CSF-VDRL/RPR; (b) positive CSF-TPPA and increased CSF protein (protein >500 mg/L) or WBC (>10×106/L), and an otherwise unexplained neurological manifestation consistent with neurosyphilis. | Negative | 4.871 |
| Wang et al 20 | 2016 | China | Prospective | 314 (123 syphilis and 191 neurosyphilis) | Reactive CSF-VDRL and CSF-TPPA in the absence of substantial contamination of CSF with blood | Negative | 256.4 |
| Mothapo et al 16 | 2015 | The Netherlands | Retrospective | 103 (87 syphilis and 16 neurosyphilis) | Positive CSF-RPR | 56 participants were positive | 76.3 |
| Marra et al 17 | 2010 | USA | Prospective | 145 (116 syphilis and 29 symptomatic neurosyphilis) | Symptomatic neurosyphilis was defined as hearing or visual loss regardless of CSF abnormalities. | Positive | 250 |
CSF, cerebrospinal fluid; CXCL13, CXC motif chemokine 13; RPR, rapid plasma reagin; TPPA, Treponema pallidum particle agglutination; TRUST, toluidine red unheated serum test; VDRL, Venereal Disease Research Laboratory; WBC, white blood cell.