Preferences on the uptake and completion of single- or three-dose regimen of benzathine penicillin G injection for the treatment of late syphilis: a discrete-choice experiment.

BACKGROUND: Notifications of syphilis in Australia have increased since 2011, particularly among gay and bisexual men who have sex with men (GBMSM). Adherence to current late latent syphilis treatment regimen is low-moderate, which is a significant health issue. To address this treatment non-compliance, a single high-dose benzathine benzylpenicillin G regimen has been under clinical trial. This study aimed to determine which attributes of either a three-dose or single-dose benzathine benzylpenicillin G regimen for treating late latent syphilis were preferred, and which attributes were deemed most important by a sample of GBMSM in Australia.

METHODS: A discrete-choice experiment survey was administered to GBMSM. This included two experiments: (1) treatment Day 1, and (2) completion of a full course. Random parameters logit model and latent class analysis were used to analyse choices of preferred attribute levels, and attributes deemed most important by respondents.

RESULTS: A total of 309 respondents completed the survey, having a mean age of 42.35 (±15.4) years. The choices revealed respondents' preferred attribute levels that were related to the single high-dose regimen, such as one injection on Day 1, the use of a shorter and thinner needle, a single injection, and a single appointment to complete the treatment course. Respondents preferred a shorter injection time. The pain on treatment Day 1, and the total number of injection(s) and appointment(s) to complete a treatment course were of most concern to respondents.

CONCLUSIONS: The GBMSM respondents preferred one injection and one appointment for a full treatment course, which supports efforts to develop a single high-dose benzathine benzylpenicillin G regimen for late latent syphilis treatment.