Sex differences in the incidence and clearance of anal human papillomavirus infection among heterosexual men and women in Liuzhou, China: An observational cohort study

Abstract

Anal cancer is primarily caused by human papillomavirus (HPV) infection in both men and women. However, little is known about the sex differences in the natural history of anal HPV infection in a heterosexual population. From May 2014 to March 2016, perianal/anal canal (PA) swab samples were collected semiannually from 2,302 heterosexual men and 2,371 heterosexual women aged 18–55 years old in Liuzhou, China. The specimens were genotyped for HPV DNA by polymerase chain reaction. The incidence rate ratio (IRR) and clearance rate ratio (CRR) were used to analyze the sex differences of incidence and clearance by Poisson regression, respectively. The incidences of PA oncogenic HPV in men and women were 3.4 per 1,000 person‐months and 8.6 per 1,000 person‐months, respectively, with an IRR of 0.39 (95% confidence interval (CI), 0.29–0.54 for men versus women) (p < 0.0001). The CRR of PA oncogenic HPV infection for men versus women was 1.54 (95% CI, 1.17–2.03) (p = 0.0022). At 12 months, 44% (20/45) of HPV 16/18 infections among women remained positive, whereas no (0/7) infections persisted among men (p = 0.0350). Both the higher incidence and slower clearance of anal carcinogenic HPV infection among women may lead to a higher burden of anal cancer among women than among men in a heterosexual population.

Sequential Acquisition of Human Papillomavirus Infection at Genital and Anal Sites, Liuzhou, China

“…In the same cohort in Liuzhou, we observed a longer persistence of any HPV type in both genital and anal sites in women compared with men (12,19). This observation is concordant with the data in the analysis we describe in this article, showing that the HRs of incident infection by any type of HPV seems higher in women who were positive for the same HPV type at the other site versus women who Figure 2.…”

Incidence, Persistence, and Clearance of Anal Human Papillomavirus among Men Who Have Sex with Men in China: An Observational Cohort Study

“…HPV6 was also the genotype with lowest clearance rate (94.9/1000 pm) in a previous longitudinal study conducted among all men in a large Chinese city; however, clearance rates of most HPV genotypes in that study were much higher than those reported here. HPV 6 may be one of the most persistent genotypes in China, which could lead to a higher disease burden of anal warts [ 28 , 33 ].…”

Epidemiology and Burden of Human Papillomavirus and Related Diseases, Molecular Pathogenesis, and Vaccine Evaluation

“…It is worth noting that even if the HPV burden is low in men than women, this does not mean they are poor carriers of the virus. Indeed, Beachler et al reported that the clearance rate of HPV is lower in men, an idea not supported by studies carried out by Wei et al (31,32). However, considering the large number of samples obtained from 18 countries combined (>24,000 participants) and a relatively long period of observation in this study, it is reasonable to admit that men have a low clearance rate because they are less likely to develop natural anti-HPV immunity compared with women (33) who clear the infection within a relatively shorter period than men.…”