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Observational Study
. 2018 Nov 13;67(11):1750-1759.
doi: 10.1093/cid/ciy348.

Risk Factors and Incidence of Syphilis in Human Immunodeficiency Virus (HIV)-Infected Persons: The HIV Outpatient Study, 1999-2015

Richard M Novak  1 , Abdelhamid Ghanem  1 , Rachel Hart  2 , Douglas Ward  3 , Carl Armon  2 , Kate Buchacz  4 ; HIV Outpatient Study Investigators
Collaborators, Affiliations
Observational Study

Risk Factors and Incidence of Syphilis in Human Immunodeficiency Virus (HIV)-Infected Persons: The HIV Outpatient Study, 1999-2015

Richard M Novak et al. Clin Infect Dis. .

Abstract

Background: Since 2000, the incidence of syphilis has been increasing, especially among gay, bisexual, and other men who have sex with men (MSM) in the United States. We assessed temporal trends and associated risk factors for newly diagnosed syphilis infections among human immunodeficiency virus (HIV)-infected patients during a 16-year period.

Methods: We analyzed data from the HIV Outpatient Study (HOPS) cohort participants at 10 US HIV clinics during 1999-2015. New syphilis cases were defined based on laboratory parameters and clinical diagnoses. We performed Cox proportional hazards regression analyses of sociodemographic, clinical, and behavioral risk factors for new syphilis infections.

Results: We studied 6888 HIV-infected participants; 641 had 1 or more new syphilis diagnoses during a median follow-up of 5.2 years. Most participants were male (78%), aged 31-50 years, and 57% were MSM. The overall incidence was 1.8 (95% confidence interval [CI], 1.6-1.9) per 100 person-years (PY) and it increased from 0.4 (95% CI, .2-.8) to 2.2 (95% CI, 1.4-3.5) per 100 PY during 1999-2015. In multivariable analyses adjusting for calendar year, risk factors for syphilis included age 18-30 years (hazard ratio [HR], 1.3 [95% CI, 1.1-1.6]) vs 31-40 years, being MSM (HR, 3.1 [95% CI, 2.4-4.1]) vs heterosexual male, and being non-Hispanic black (HR, 1.6 [95% CI, 1.4-1.9]) vs non-Hispanic white.

Conclusions: The increases in the syphilis incidence rate through 2015 reflect ongoing sexual risk and highlight the need for enhanced prevention interventions among HIV-infected patients in care.

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Conflict of interest statement

Potential conflicts of interest. R. H. has received payments from the National Institutes of Health. R. M. N. has received fees for expert testimony from Wilson, Sonsini, Goodrich, and Rosati. All other authors report no potential conflicts. Authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Cohort selection flowchart, human immunodeficiency virus (HIV) Outpatient Study, 1999–2015. Abbreviations: HOPS, HIV Outpatient Study; MSM, men who have sex with men.
Figure 2.
Figure 2.
Syphilis incidence and testing rates by year, human immunodeficiency virus Outpatient Study, 1999–2015 (N = 6888).
Figure 3.
Figure 3.
Syphilis incidence rates per 100 person-years with 95% confidence interval bars, the HIV Outpatient Study, 1999–2015 (N = 6888). Abbreviations: HIV, human immunodeficiency virus; LCI, lower confidence interval; MSM, men who have sex with men; UCI, upper confidence interval.
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References

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