Identification of the factors associated with post-treatment asymptomatic neurosyphilis in HIV-negative patients with serological non-response syphilis: a retrospective study.

Some syphilis patients do not exhibit an appropriate serological response after treatment despite the absence of any clinical evidence of treatment failure or reinfection. This condition is called "serofast syphilis" or "serological non-response syphilis." This study explored the incidence of asymptomatic neurosyphilis (ANS) and related factors in 324 asymptomatic patients with serological non-response syphilis. We analyzed descriptive statistics stratified by the presence of asymptomatic neurosyphilis for the basic characteristics of samples. Bivariate analysis was conducted to assess correlations between outcomes and potential predictors. Variables significant in the bivariate analysis (p<0.1) were entered into multivariable logistic regression models. All p-values were two-sided with a significance threshold of p<0.05. The results indicated that 89 of 324 patients had ANS (incidence of 27.5%), and the greatest risk factors were a < fourfold decrease in serum rapid plasma reagin (RPR) titers after treatment and current serum RPR titers >1:32. Our findings suggest that ANS is common among syphilis patients, and patients with a fourfold decrease in serum RPR titers after treatment and current serum RPR titers >1:32 are more likely to develop ANS.