Exploring syphilis activity for personalized treatment strategies in latent syphilis: a 2-year cohort study

Background Relying simply on the stage of latent syphilis may lead to excessive treatment strategies. Utilizing nontreponemal immunoglobulin M (IgM) antibodies to assess syphilis activity and tailor treatment strategies may offer enhanced therapeutic advantages. Objectives To investigate whether nontreponemal IgM antibodies can serve as a serological marker for assessing the activity of latent syphilis and inform personalized treatment strategies. Methods We evaluated nontreponemal IgM antibodies in 412 latent syphilis patients and conducted a 2-year follow up to analyze their rate of seroconversion (the change from seropositive to seronegative status), to evaluate whether nontreponemal IgM antibodies could assess the activity of latent syphilis. Results The positive nontreponemal IgM group demonstrated a lower seroconversion rate (P =0.0178) and achieved seroconversion slower compared with the negative group (hazard ratio: 0.386). Early-stage patients exhibited higher nontreponemal IgM antibody levels (P P =0.018) than late-stage patients. Elderly patients showed lower nontreponemal IgM antibody levels (P P =0.0022) than non-elderly patients. Conclusions Latent syphilis patients with positive nontreponemal IgM require a longer time to seroconversion and exhibit a lower seroreversion rate, indicating their higher syphilis activity. Nontreponemal IgM antibodies can serve as a serological marker for detecting syphilis activity in latent syphilis. It is recommended to test for nontreponemal IgM antibodies before treatment to identify syphilis activity for personalized treatment.