Sequential Acquisition of Human Papillomavirus Infection between Genital and Anal Sites in Men and Women in Liuzhou, China: An Observational Cohort Study

Abstract

Background: The aim of this study was to assess the sequential risk of acquiring a concordant human papillomavirus (HPV) infection in a genital (or anal) site following an anal (or genital) HPV infection in men and women. Method: Independent specimens from 2309 male and 2378 female genital and anal sites were collected and genotyped for HPV at months 0, 6 and 12. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated by Cox regression to analyze the sequential acquisition of a genotype-concordant HPV infection in the genital (or anal) site following an incident HPV infection in the anal (or genital) site in men and women. Findings: The incidence rate of anal HPV infection was 8·8 (95% CI: 5·2- 14·8) and 3·8 (95% CI: 2·9-4·9) per 1000 person-months in men with or without a prior genital HPV infection of the same type (HR, 2·6; 95% CI: 1·4-4·6); these values were 25·9 (95% CI: 21·0-31·9) and 6·2 (95% CI: 5·3-7·3) in women (HR, 4·4; 95% CI: 3·4-5·8). Compared with men, women had a higher risk of sequentially acquiring a concordant anal HPV infection following a genital HPV infection (P = 0·0013). Women with prior anal HPV infections also had a higher risk of subsequent genital concordant HPV infections (HR, 1·9; 95% CI: 1·2-3·1), whereas for men, a significant difference was not found for any HPV type (HR, 0·7; 95% CI: 0·2-1·9). Among participants without a prior anogenital HPV infection, the incidence rate of any HPV infection was higher at the genital site than at the anal site in both sexes (both P < 0·0001); however, among subjects with prior infection of the other site, females became more likely to acquire an anal infection than a genital infection, although the difference was not statistically significant (P = 0·0758). Interpretation: Both men and women with prior HPV infection at the genital (or anal) site had a higher risk of sequentially acquiring a concordant HPV infection at the anal (or genital) site. In addition to sexual intercourse, autoinoculation might play an important role in anogenital HPV infection in both sexes, especially anal HPV infection in women. Funding Statement: This study was supported by grant 2015ZX09101034 from National Science and Technology Major Project, grants 81673240 and 81601805 from National Natural Science Foundation of China, and grant 2018ZY001 from the Scientific Research Foundation of State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Written informed consent was obtained from each participant, and the protocol was approved by the Ethics Committee of the Liuzhou Center for Disease Control and Prevention.