Article Text
Statistics from Altmetric.com
Syphilis is a spirochetal infection with multiple manifestations. In recent years, syphilis has re-emerged as a significant public health problem in many countries including China.1 However, the factors that predict serological response after syphilis treatment have not been well-defined.
We performed a retrospective study of patients who were diagnosed as having early syphilis in our clinic between the years 2000 and 2010. Analysis of factors determining the serological response to treatment was performed in HIV-negative patients with early syphilis, using demographic characteristics, clinical characteristics (i.e., sex, age, residence, coinfection with other STDs, baseline rapid plasma reagin (RPR) titre, fluorescent treponemal antibody absorption (FTA-ABS) IgM, syphilis stage and treatment), and behavioural characteristics (i.e., sexual orientation, number of sex partners and condom use). Serological cure was defined as a negative RPR test or a ≥4-fold decreased titre at 6 months after treatment, and serofast status was defined as a ≤2-fold decreased titre or persistent titres that did not meet criteria for treatment failure.2
Data of 501 patients with serological cure or serofast status was collected. Of the 501 patients, 426 (85%) achieved serological cure and 75 (15%) were serofast at 6 months. For primary and secondary syphilis, 86.2% (75/87) and 93.0% (238/256), respectively, exhibited serological cure by 6 months after treatment. For patients with early latent syphilis, however, a lower proportion of 71.5% (113/158) had serological cure at 6 months. In bivariate analysis, serological cure was associated with higher baseline RPR titres, positive FTA-ABS-IgM, earlier syphilis stage and treatment with benzathine penicillin (P≤0.05). Multivariate analysis revealed that having a baseline RPR titre ≥1:32 was associated with a >6-fold increased probability of serological cure, compared with RPR titre <1:32 (adjusted odds ratio (AOR)=6.78; 95% confidence interval (CI)=1.89–24.27). FTA-ABS-IgM positive was associated with increased probability of serological cure, compared with FTA-ABS-IgM negative (AOR=3.15, 95%CI=1.02–9.77). Early latent syphilis were negatively associated with serological cure at 6 months, compared with primary syphilis (AOR=0.14, 95%CI=0.04–0.51).
We identified key factors associated with serological response to syphilis treatment, which have implications for the management of early syphilis and expected outcomes after therapy. The CDC's guidelines for treatment of syphilis2 have categorised serological follow-up on the basis of stages of infection, but the additional effect of the baseline nontreponemal titre and treponema pallidum-IgM on response to treatment should be considered.
Acknowledgments
Qiu-Ning Sun, Hong-Zhong Jin, Yue-Hua Liu, Dong-Lai Ma, from Department of Dermatology, Peking Union Medical College Hospital, China provided insightful suggestions at several stages of this study.
Footnotes
-
Contributors H-YZ conceived, designed and coordinated the study; L-NW coordinated data collection; JL organised data for analysis; JL analysed the data, interpreted the results and wrote the manuscript.
-
Competing interests None.
-
Patient consent Obtained.
-
Ethics approval The study was approved by the ethics committee of Peking Union Medical College.
-
Provenance and peer review Not commissioned; internally peer reviewed.