Potential Predictors for Serofast State after Treatment among HIV-Negative Persons with Syphilis in China: A Systematic Review and Meta-Analysis

BACKGROUND: Several studies have been conducted in China in order to investigate the potential predictors of serofast state after treatment among syphilitic patients. However, there is a remarkable diversity among the results. This meta-analysis was conducted to assess potential predictors of serofast among syphilitic patients in China. METHODS: International and national electronic databases were searched up to September 2013. Reference lists of retrieved articles were also reviewed. Cohort or case-control studies addressing risk factors of serofast among syphilitic patients were included in this study. RESULTS: We assessed 27 separate studies involving overall 6682 HIV-negative participants with syphilis of which 1962 remained in the serofast state. The serofast was positively associated with older age(P(trend)=0.001), female(summary risk ratio[sRR]=1.50, 95%CI:1.34–;1.68), latent syphilis(sRR(latent vs primary)=3.17, 95%CI: 2.66–;3.77; sRR(latent vs secondary)=2.00, 95%CI: 1.48–;2.69) as well as non-penicillin treatment(sRR =2.99, 95%CI:2.45–;3.67), but negatively associated with higher baseline titers(sRR(>1:32 vs ≤1:32)=0.63, 95%CI: 0.54–;0.75). Compared with healthy group and serological cure group, respectively, the levels of CD4 (+), IL-2, and IL-6 among serofast patients were decreased (standardized mean difference[SMD]<0, P<0.05), but the levels of CD8(+) and IL-10 were increased(SMD>0, P<0.05). Some studies also hinted the serofast was associated with subtypes i of treponema pallidum(TP) repeat gene (RR (i vs d)=4.67,95%CI: 1.31–;16.69) and TP occult infection. CONCLUSION: The age, gender, stage of infection, baseline titers, treatment drug, cellular immune suppression and disorders, TP occult infection and subtypes i of TP repeat gene should be considered as important predictors of serofast. However, until now the definition and mechanism of serofast has still been not clear.