Women whose male sexual partners consistently use condoms are significantly less likely to become infected with human papilloma virus (HPV) than women whose partners do not use condoms or use them inconsistently, a longitudinal study published in the June 22nd edition of the New England Journal of Medicine has found.
The efficacy of male condoms at preventing sexually transmitted infections has become involved in political controversy in the US where Christian conservatives want condom labels to warn about the risk of infections even if condoms are used and where state funded abstinence-only sexual health “education” programmes only allow the mention of condoms in the context of their failure rate. Evidence already exists that the correct and consistent use of condoms can substantially reduce the risk of infection with HIV, gonnorhoea, Chlamydia and herpes simplex virus. An editorial in the NEJM notes that the latest study shows that condom use “also reduces the risk of HPV infection in women.”
To see if condoms reduced the risk of infection with HPV, investigators recruited 82 female university students aged between 18 and 22 who had never had sex to a study. Gynaecological examinations were conducted every four months and samples were taken to check for infection with HPV and for the presence of pre-cancerous changes in the cervix that certain strains of HPV can cause - squamous intraepithelial lesions. The students also kept electronic diaries in which they recorded information about their daily sexual activity. The median duration of participation in the study was a little under three years.
The incidence of infection with genital HPV infection was 38 per 100 patient years amongst women who used condoms all the time compared to 83 per 100 patient years amongst women who used condoms less than 5% of the time. This difference was statistically significant (p = 0.003). In addition, the investigators noted that consistent condom use was associated with a similar reduction in the risk of becoming infected with a strain of HPV known to be associated with potentially cancerous changes to cells in the cervix.
In further analysis, the investigators looked to see if the use of condoms reduced the risk of developing pre-cancerous cell changes in the cervix. None of the women who reported 100% condom use had any cervical squamous intraepithelial lesions during 32 person years of follow-up compared to 14 in 97 person years amongst women who reported not using condoms or inconsistent condom use.
“The results of our study…suggest that male condoms effectively reduced the risk of male-to-female genital HPV transmission”, write the investigators. They note that HPV can be transmitted by non-penetrative sex and that condom use can be less than perfect, therefore “it is not surprising that some infections can still be detected among women reporting consistent use.” Nevertheless they were encouraged that “women in this cohort, who were new to sexual intercourse, were able to reduce their risk of HPV infection through the consistent use of condoms by their male partners.”
The results of the study have already become embroiled in US ideological and politcal debates. Christian conservatives have said the study showed a high "failure" rate for condoms, however, Californian Democrat Congressman Henry Waxman said, "this study provides important evidence for the effectiveness of condoms in reducing the risk of HPV transmission. The data further undermines the right-wing call for misleading labels on condoms claiming the opposite and reminds us that what matters in public health is science, not ideology."
Winder RL et al. Condom use and the risk of genital human papillomavirus infection in young women. NEJM 354: 2645 – 2654, 2006.
Steiner MJ et al. Condoms and sexually-transmitted infections. NEJM 354: 2642 – 2643, 2006.