Mediators of the association between age of first sexual intercourse and subsequent human papillomavirus infection

Objective. Previous studies have demonstrated that early age of first sexual intercourse is associated with human papillomavirus (HPV) infection. The objective of this study was to identify a set of risk behaviors and partner characteristics that mediate the association between age of first sexual intercourse and subsequent HPV infection in adolescent and young adult women. Methods. Female university students completed surveys and underwent HPV testing every 6 months for up to 3 years. HPV-positive participants were matched to HPV-negative participants (252 pairs, total N = 504). Associations were examined between risk behaviors/partner characteristics and both age of first sexual intercourse and HPV infection. Those variables associated with either age of first sexual intercourse or HPV infection were entered into a generalized estimating equation (to account for the matched study design) modeling the association between age of first sexual intercourse and HPV infection. Results. Mean age of first sexual intercourse was 16.7 (+/-1.8) years, and early age of first sexual intercourse was associated significantly with HPV infection ( beta = -0.20; odds ratio: 0.82; 95% confidence interval: 0.74-0.90). The association was mediated by number of sexual partners in the past 6 months, history of sexually transmitted infection, alcohol and drug use related to sexual behaviors, and partner's number of sexual partners. Conclusion. A set of behavioral risk factors and partner characteristics partially mediate the association between age of first sexual intercourse and subsequent HPV infection.