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(sRRlatent vs primary=3.17, 95%CI: 2.66-;3.77; sRRlatent 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.
Keywords: China; Interleukin; Meta-analysis; Serofast; Syphilis; T-lymphocyte subset.