Prevalence of and risk factors for neurosyphilis in syphilitic patients with persistently positive nontreponemal serological tests

Abstract

Objective To investigate the prevalence of and risk factors for neurosyphilis in syphilitic patients with persistently positive nontreponemal serological tests after regular therapy. Methods Clinical data were collected from 248 syphilitic patients with persistently positive nontreponemal serological tests after regular therapy, and analyzed retrospectively. Univariate analysis, multivariate logistic regression analysis and receiver operating characteristic (ROC)curve analysis were performed to assess factors associated with neurosyphilis. Results Of the 248 patients, 25 (10.1%)were diagnosed with neurosyphilis. As univariate analysis showed, the occurrence of neurosyphilis was associated with the degree of decline in serum toluidine red unheated serum test (TRUST)titers (χ2= 20.663, P 0.05). Multivariate logistic regression analysis revealed that persistent positive serum TRUST titers were a risk factor for neurosyphilis (OR = 4.685, 95% CI= 2.552-8.601, P < 0.05). ROC curve analysis showed that the best cut-off point of persistent positive serum TRUST titer was 1∶8 for predicting neurosyphilis, with the area under the curve (AUC)being 0.907. Conclusion Serum TRUST titers are somewhat valuable for predicting neurosyphilis in syphilitic patients after regular therapy. Key words: Syphilis; Neurosyphilis; Syphilis serodiagnosis; Risk factors