Anal sex is a behavioural marker for laboratory-confirmed vaginal sexually transmissible infections and HIV-associated risk among African-American female adolescents

Background: African-American females are disproportionately affected by HIV and sexually transmissible infections (STIs). The prevalence of anal sex and its association with other sexual risk behaviours is understudied in this population. Methods: Participants were 715 African-American females, 15 to 21 years old, who had reported sexual activity in the previous 60 days. Data collection included an audiocomputer assisted self-interview (ACASI) and a self-collected vaginal swab specimen assayed using nucleic acid amplification tests to detect the presence of Chlamydia trachomatis and Neisseria gonorrhoeae, and real-time polymerase chain reaction assay to detect Trichomonas vaginalis. Results: Approximately 10.5% reported anal sex, at least once, during the 60 days before completing the computerised baseline assessment. The prevalence of any STI was significantly greater among adolescents reporting recent anal sex (40% tested positive for at least one of three laboratory-confirmed STIs) relative to those adolescents not reporting anal sex (27.5% STI prevalence). Of the 10 outcomes comprising the sexual risk profile, seven achieved bivariate significance, with each of the differences indicating greater risk for those recently engaging in anal sex. In multivariable controlled analyses, six of the seven measures retained statistical significance. Conclusions: African-American adolescent females who engage in penile-anal sex may experience an elevated risk of vaginally-acquired STIs. The findings suggest that, among those having penile-anal sex, several HIV/STI-associated sexual risk behaviours are significantly more prevalent. Thus, penile-anal sex may be an important proxy of overall sexual risk behaviours and can be readily assessed during paediatrician visits as part of a sexual history.