Condoms Help Block HPV Infection in Young Women

SEATTLE, June 22 ? Among newly sexually active women, consistent condom use by their partners reduced their risk of human papilloma virus (HPV) infection, researchers reported.

Although the use of condoms by men has been shown to substantially reduce the risk of HIV transmission, data on the effectiveness of condoms in reducing other sexually transmitted infections, including HPV, are limited or not specifically designed for HPV infection, the investigators wrote in the June 22 issue of the New England Journal of Medicine.

Even after the recently approved quadrivalent vaccine for HPV becomes widely available, the vaccine will not protect against all HPV types, said Rachel Winer, Ph.D., at the University of Washington here, and colleagues.

To answer questions about of HPV-condom protection, a team of researchers studied 82 female University of Washington undergrads (ages 18 to 22) who had never had vaginal intercourse or reported their first intercourse with one male partner during the previous three months.

Cervical and vulvovaginal samples for DNA testing and Pap tests were collected at gynecologic examinations every four months, while every two weeks, the women recorded their daily sexual behavior in a Web-based diary.

The results of the study showed that male condoms effectively reduce the risk of male-to-female cervical and vulvovaginal HPV transmission, Dr. Winer said.

Women whose partners had used condoms at all times during the eight months before testing were 70% less likely to acquire a new infection, compared with women whose partners used condoms less than 5% of the time, after adjustment for the number of new partners and the estimated number of the man's previous partners, Dr. Winer reported.

Even women whose partners used condoms more than half the time had a 50% risk reduction compared with the 5% users, she said.

The incidence of genital HPV infection was 37.8 per 100 patient-years at risk for women whose partners used condoms for all instances of intercourse during the eight months before testing (95% CI 27.2-49.4%), the researchers reported.

This compared, they said, with 89.3 per 100 patient-years at risk for women whose partners used condoms less than 5% of the time (adjusted hazard ratio 0.3; 95% CI, 0.1 to 0.6, adjusted for the number of new partners and the number of the man's previous partners).

Similar associations were observed when the analysis was restricted to high-risk and low-risk types of HPV as well as HPV types 6, 11, 16, and 18 (in the new quadrivalent HPV vaccine), the researchers reported.

In women reporting 100% condom use by partners, no cervical squamous intraepithelial lesions were detected in 32 patient-years at risk, whereas 14 incident lesions occurred in 97 patient-years at risk among women whose partners did not use condoms or used them less consistently.

In addition, the report of new partners in the previous eight months was associated with an increased risk of HPV infection, the researchers reported, while more frequent condom use by partners and lack of previous partners for the man were both associated with a decreased risk.

"Given that HPV is transmissible through non-penetrative sexual contact with both male and female partners and that imperfect condom use does occur, it is not surprising that some infections were still detected among women reporting consistent use," the authors concluded.

"It is encouraging, however, that the women in this cohort, who were new to sexual intercourse and condom use, were able to reduce their risk of HPV infection through the consistent use of condoms by male partners," they added. "Furthermore, our results suggest that consistent condom use offers similar protection against both high-risk and low-risk types of HPV. Even after the quadrivalent vaccine for HPV types 6, 11, 16, and 18 becomes available, consistent condom use by their partners may protect women against infection with other high-risk types of HPV that put them at risk for cervical cancer."

Dr. Winer reported having received consulting fees from Merck, while other study authors have received fees from Merck and GlaxoSmithKline and research funding from Merck.

In an accompanying editorial, Markus Steiner, Ph.D., and Willard Cates, Jr., M.D., at Family Health International in Research Triangle Park, N.C., wrote that despite the study's welcome findings, there is concern that condom protection will give a false sense of security. "We should refer," they said, "to safer sex rather than safe sex." Furthermore, they emphasized, condoms reduce STD risk only when they are used.

In addition, the editorial said, although Dr. Winer's team presented clear evidence that condom use reduces the risk of HPV infection in women, "the protection that condoms offer against a specific sexually transmitted infection cannot be precisely quantified."

"Condoms are just one tool in the armamentarium against sexually transmitted infections," they wrote. "Only by harnessing all the evidence-based prevention tools can we move toward true sexual health."