Syphilis testing among spouses of patients with syphilis in Japan: an epidemiological study using an administrative claims database

Abstract

The number of syphilis cases reported in Japan, transmitted mainly by heterosexual contact, has been increasing since 2014. However, Japan has not introduced partner services programmes, and it remains unclear whether contacts of patients with syphilis undergo testing. This study aimed to estimate the proportion of spouses of patients with syphilis who underwent syphilis testing. We retrospectively identified patients who had recently started syphilis treatment as well as their spouses from a Japanese claims database for employee health insurance plans, collected between 2010 and 2017. Spousal syphilis testing was defined as either a nontreponemal or treponemal test within three months after the index patient started treatment. We determined the proportion of spousal syphilis testing and analysed its associations with patient and spouse characteristics, and year of syphilis treatment. Of the 217 patients who were identified to have started syphilis treatment, 29 (13.3%) spouses underwent syphilis testing: 23/182 (12.6%) among wives, and 6/35 (17.1%) among husbands, of male and female index patients, respectively. Among wives aged <45 years, the proportion tested declined over time. Despite the rise in syphilis incidence, the proportion of spouses tested, including women of reproductive age, declined. In Japan, partner services programmes need to be implemented to control sexually transmitted infections.