The outcome of treatment of early latent syphilis and syphilis with undetermined duration in HIV-infected and HIV-uninfected patients.

The aim of the study was to compare the outcome of syphilis treatment in HIV-infected and -uninfected patients. An observational study on patients diagnosed with early syphilis in three genitourinary clinics in the UK between January 2003 and June 2005 was conducted. Failure of the initial Venereal Disease Research Laboratory (test) (VDRL) titre to decrease four-fold within 12 months in the absence of history of re-infection was considered as treatment failure. During the study period, 190 HIV-uninfected and 129 HIV-infected patients were diagnosed, and 161 (84%) HIV-uninfected and 100 (77.5%) HIV-positive patients with diagnosis of syphilis who had 24 months follow-up syphilis serology results were included in the study (P = 0.10). There were 381 and 508 follow-up episodes for HIV-infected and -uninfected patients, respectively, within 24 months. One HIV-infected patient was diagnosed with neuro-syphilis. After 12 months, 102 (63%) HIV-uninfected and 76 (70%) HIV-infected patients were treated (P = 0.04). On Cox proportional hazard model, successful treatment after 12 months was associated with having VDRL titre more than 1:6 (hazard ratio [HR] 1.011; 95% confidence interval [CI], 1.004-1.019; P = 0.002). Those with negative immunoglobulin M enzyme immunoassay were less likely to have been successfully treated after 12 months (HR 0.676 [95% CI 0.518-0.883]; P = 0.004). HIV sero-status, age, sex group and treatment regimen were not associated with success of treatment. In conclusion, HIV sero-status did not play a role in the outcome of syphilis treatment. Treatment failure in a proportion of HIV-infected patients is due to a slower decline in VDRL titre rather than lack of response to treatment.