Characteristics and risk of syphilis diagnosis among HIV-infected male cohort: a population-based study in Houston, Texas.

Background: This population-based study assessed the characteristics, timing, and risk of syphilis diagnoses among HIV-infected males in Houston, Texas.

Methods: A retrospective cohort of males newly diagnosed as having HIV between January 2000 and December 2002 was constructed using HIV surveillance data. These individuals were cross-referenced to sexually transmitted disease surveillance data to ascertain early syphilis diagnoses for the subsequent 10 years. Multivariable Cox regression was used to identify risk factors for syphilis diagnosis while controlling for the effects of covariates.

Results: Approximately 6% of the HIV-infected male cohort received early syphilis diagnoses during a 10-year period. Of these comorbid individuals, 40.8% received an incident syphilis diagnosis 5 years or more after their HIV diagnosis. Men who have sex with men (MSM) transmission risk was associated with significantly increased hazard of having a syphilis diagnosis in multivariable analysis (adjusted hazard ratio [HR] of a syphilis diagnosis, 5.24; 95% confidence interval, 3.41-8.05). Compared with men who were older than 40 years at HIV diagnosis, those 13 to 19 years old were 4.06 (2.18-7.55) times more likely to obtain a syphilis diagnosis. The HRs of having an HIV-syphilis comorbidity decreased as age increased. Compared with whites, non-Hispanic African Americans had 1.59 (1.11-2.26) times increased risk of having a subsequent syphilis diagnosis. Risk-stratified HRs showed that MSM had an increased risk of contracting syphilis in all race/ethnicity and age groups.

Conclusions: This study suggests that HIV-positive African Americans, youth, and MSM had increased risk of having a subsequent syphilis diagnosis. Targeting these groups with STI prevention messaging may be beneficial to reducing comorbidity.