1 Department of Family and Preventive Medicine, University of South Carolina School of Medicine, Columbia, SC 29203.
2 Florida State University College of Medicine, Tallahassee, FL 32306.
Recent articles in the American Journal of Epidemiology described the use of postcoital vaginal prostate-specific antigen levels to evaluate the effectiveness of the female condom as a semen barrier (1, 2). The findings of these studies indicated that women who were trained in the use of the female condom were exposed to semen in 721 percent of uses. Commenting on these findings, Steiner et al. (3) reviewed the continuing debate about male condom effectiveness and reasserted the conclusion of a recent report sponsored by the National Institutes of Health: A lack of clinical evidence that condom use prevents all sexually transmitted infections (STIs) does not prove that condoms are in fact ineffective.
In their commentary, Steiner et al. (3) further seek to assert and explain condom effectiveness in the face of these relatively high rates of semen exposure. Implicit in their response is the assumption that condoms are effectivea position that seems to lead Steiner et al. to overlook or minimize evidence that condoms may be less than optimally effective, perhaps because of concern that doubts about condom effectiveness may result in decreased condom use. Opposing this viewpoint are persons (some indicted by Steiner) who refuse to acknowledge any degree of condom effectiveness and will go to great lengths to convince others that condoms do not work.
Between these two positions are the many researchers, like the authors of the recent studies (1, 2), who are working to objectively measure the degree of risk reduction provided by barrier methods, including both male and female condoms. These investigators generally acknowledge that condoms, when used consistently and correctly, should prevent acquisition of STIs if they do not slip, break, or suffer from other mechanical damage and if the STI in question is transmitted solely by the exchange of body fluids. (Infectious agents that are transmitted through direct contact, such as human papillomavirus, represent a different debate.) However, realists also acknowledge that inconsistent condom use is common, that even consistent users frequently use condoms incorrectly, and that method failure can and does occur in spite of consistent and correct use (4).
Given that condom failures do occur, it is important to improve existing research methods and continue research to quantify the degree to which condom use, "typical" or "theoretical," actually reduces STI risk. The degree of risk reduction provided is likely to be affected not only by user and method failure rates but also by factors such as STI infectivity, duration, mode of transmission, and frequency of intercourse. Furthermore, the distinction between one-time and cumulative risk must be clearly explained, since even a small per-exposure risk of infection can result in a significant cumulative infection risk given a substantial number of exposures to an infected sexual partner (5).
Accurate and precise communication about condom effectiveness is important. We must avoid discouraging condom use by understating condom effectiveness; however, we must avoid encouraging sexual risk-taking by instilling a false sense of security. On the basis of currently available evidence, it seems most appropriate to assert that condom use appears to reduce but not eliminate the risk of many STIs. The degree to which risk is reduced remains unclear.
REFERENCES