Effect of highly active antiretroviral therapy on incidence of early syphilis in HIV-infected patients

OBJECTIVES: To evaluate the incidence of early syphilis based on time from initiation of highly active antiretroviral therapy (HAART) in human immunodeficiency virus (HIV)-infected patients. STUDY DESIGN: Five hundred thirty-nine HIV-positive patients undergoing HAART were followed up to 4 years to identify early (primary or secondary) syphilis. Incidence rate trends according to time from HAART initiation were evaluated by Poisson regression after adjustment for calendar year. RESULTS: With median follow-up of 2.9 years, 56 (10.4%) patients experienced early syphilis, 17 (3.2%) with primary syphilis, and 39 (7.2%) with secondary syphilis. The overall incidence rate of early syphilis for 4 years after the start of HAART was 4.57 per 100 person-years (95% confidence interval, 3.45-5.93). The incidence rate of early syphilis significantly increased in proportion to the years after the start of HAART (3.4-6.1 per 100 person-year, P for trend <0.001). CONCLUSIONS: Early syphilis incidence in HIV-infected patients increased in proportion to HAART duration. The finding suggests that screening for syphilis in HIV-infected patients who initiate HAART should be encouraged with attention to the time passed since HAART initiation.