Syphilis testing behavior following diagnosis with early syphilis among men who have sex with men--San Francisco, 2005-2008.
BACKGROUND
In San Francisco, men who have sex with men (MSM) with early syphilis are at high risk of reinfection. We described syphilis testing behavior among MSM after diagnosis, identified factors associated with not testing, and developed algorithms to identify nontesters.


METHODS
We used syphilis surveillance data from 2005 through 2008 to describe follow-up testing behavior among MSM with early syphilis and titers of non-treponemal serologic tests ≥1:16. We analyzed data from contact-tracing interviews to identify factors associated with not testing during the 1 to 6 months post-diagnosis. We developed and applied a multivariate model in a derivation set (2005-2006) and a validation set (2007-2008), respectively, calculating correct classification rates (CCR) to assess predictive ability and evaluating patient characteristics for potential interventions.


RESULTS
Among 795 MSM, 260 (33%) did not have a follow-up syphilis test. Not testing was associated with being HIV-uninfected (risk ratio [RR]: 1.9, 95% confidence interval [CI]: 1.5-2.6), residing outside of San Francisco's gay-identified neighborhood (RR: 1.7, 95% CI: 1.0-2.9), and being diagnosed at the municipal sexually transmitted disease clinic (RR: 1.5, 95% CI: 1.2-2.0) (CCR derivation set, 71.6%; CCR validation set, 71.3%). An intervention focusing on MSM with those 3 characteristics would include 13% of syphilis cases among MSM and identify 26% of nontesters.


CONCLUSIONS
Although MSM in San Francisco are at high risk for syphilis reinfection, one-third of MSM diagnosed with syphilis did not test during the 1 to 6 months post-diagnosis. Interventions to encourage follow-up testing among persons with syphilis might contribute to more effective syphilis prevention and control efforts.
Marcus
Julia L
JL
STD Prevention and Control Services, San Francisco Department of Public Health, 1360 Mission Street, San Francisco, CA 94103, USA. julia.marcus@sfdph.org
Katz
Kenneth A
KA
Bernstein
Kyle T
KT
Nieri
Giuliano
G
Philip
Susan S
SS
D000328:Adult; D000465:Algorithms; D005500:Follow-Up Studies; D018451:Homosexuality, Male; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D012008:Recurrence; D012495:San Francisco / Q000453:epidemiology; D012725:Sexual Behavior; D013587:Syphilis / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D013588:Syphilis Serodiagnosis / Q000706:statistics & numerical data*