Identifying syphilis risk networks through venue attendance in San Francisco

Prioritizing interventions for patients with syphilis who are part of large or interconnected sexual networks may be high yield for partner services, and identifying venues named by patients with syphilis who report high numbers of partners may help identify such networks. In this analysis, we explore differences between interviewed patients with early syphilis regarding where they met sex partners.

With a cross-sectional design, we examined the distribution of total reported sex partners from male index patients with early syphilis interviewed through the San Francisco Department of Public Health partner services program and the self-reported venues named as places they met sex partners. Based on the median number of total partners among male cases of syphilis who named each venue, we categorized venues into 3 levels of partner frequency: high (>15 partners reported), medium (6-15 partners reported), and low (<6 partners reported). Interviewed patients with early syphilis were then classified into these venue categories, and sociodemographic and risk behaviors from electronic medical records and interviews were compared using χ tests.

In 2011, 433 male patients with early syphilis named 32 venues. One hundred forty-three (32.3%) patients were categorized as high, 226 (51.0%) as medium, and 74 (16.7%) as low partner frequency venue users. Patients with early syphilis who reported meeting partners at high partner frequency venues were generally older, more likely to be white, have a previous syphilis infection, use methamphetamines in the previous year, and be HIV infected (all P < 0.05) compared with those who reported meeting partners at medium-frequency and low-frequency venues.

Venues where partners are met may be an appropriate proxy for network membership. Targeting additional resources, outreach, and services to clients who attend high-frequency venues may have a positive impact on syphilis prevention efforts.