UN Population Division, Department of Economic and Social Affairs,
with support from the UN Population Fund (UNFPA)
|
| UN Population Division, Department of Economic and Social Affairs, with support from the UN Population Fund (UNFPA) |
|
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The electronic version of Network is being made available by the
Population Information Network (POPIN) of the United Nations
Population Division/DESIPA and Family Health International (FHI).
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NETWORK
Vol. 16, No. 3, Spring 1996
Barrier Methods
Copyright 1996, Family Health International
Opinion: The Dual Goals of Reproductive Health
By Willard Cates Jr., MD, MPH
FHI Corporate Director of Medical Affairs
In today's global health village, the term "reproductive
health" involves preventing not only unintended pregnancy, but also
sexually transmitted diseases (STDs). The specter of HIV infection
has made protection from genital tract infection a high priority on
the world's reproductive health agenda.
As awareness of HIV and other STDs has grown, decisions about
contraceptive use have begun to involve the need to prevent STDs.
This became most obvious at the United Nations 1994 International
Conference on Population and Development in Cairo, which defined a
reproductive health agenda that encourages family planning programs
to add STD prevention services. However, the only contraceptives
currently recommended for STD/HIV prevention are barrier methods,
making them important for ensuring one's reproductive health.
Nonetheless, many in family planning programs are hesitant
to recommend barrier methods because their record in preventing
unintended pregnancies is less reliable than other contraceptives.
Some family planning clinicians worry that reliance on barrier
methods alone will produce higher rates of both unintended pregnancy
and STD/HIV. Are their fears justified?
What do we currently know about the efficacy of barrier
methods in preventing STD/HIV? Four key questions dominate the
barrier contraceptive method research agenda. Let us consider them
in order.
Question: Do condoms (male and female) really work to prevent STD and
unplanned pregnancy?
Answer: The simple answer is yes, if used consistently and correctly.
When used consistently, condoms are effective in preventing both STDs
and unplanned pregnancy. Thus, the method itself is effective against
both conditions.
Several convincing studies demonstrate the effectiveness of
condoms when used consistently. One intriguing study involved U.S.
Navy seamen on shore leave in a "high-risk" port city: None of the
29 men who reported using condoms with commercial sex workers became
infected with gonorrhea or nongonococcal urethritis, but 14 percent
of the nonusers became infected (71 of the 499 nonusers). A second
excellent study of condom use occurred among HIV-discordant couples
in Europe. None of the 123 seronegative partners prospectively
reporting consistent condom use became infected. Thus, used regularly
and correctly, condoms work effectively.
The problem is that condoms -- whether male or female devices
-- are typically used sporadically or incorrectly. Effectiveness
rates must take this into account. Using a public health model,
sexual abstinence will obviously prevent all of the risk of
unprotected sex. However, intercourse using barrier methods of
contraception, while not perfect, also provides a large measure of
protection against the risk of STD or unintended pregnancy. In fact,
plotting both abstinence and condom use on the same curve, sex
protected by barrier methods reduces 70 percent of the total risk
between unprotected sex and complete sexual abstinence. Thus, at the
policy level, condoms must continue to be emphasized and made
available.
Question: How effective are spermicidal nonoxynol-9 (N-9) agents
against HIV and the other STDs?
Answer: Based on data from well-conducted randomized controlled
trials, spermicides containing N-9 show a measurable protective
effect against specific STDs -- gonorrhea, chlamydia, trichomoniasis,
and bacterial vaginosis. In Cameroon, Thailand and the United States,
the regular use of N-9 by women attending either STD or family
planning clinics reduced cervical gonorrhea and chlamydia infections
by 20 percent to 50 percent.
However, the effect of N-9 agents on HIV transmission remains
uncertain. Despite the in vitro activity of N-9 against HIV, and its
protective effect against the simian immunodeficiency virus in Rhesus
monkeys, published data are unclear about the impact of N-9 on humans
in vivo. Among commercial sex workers in Nairobi, women who were
randomly assigned to use a contraceptive sponge with N-9 had higher
levels of vaginitis, genital ulcers, and HIV infection than those
using a placebo. However, other observational studies in Africa and
Asia show more favorable results -- HIV infection was reduced among
N-9 users. Thus, these data inconsistencies mean the jury is still
out on the scientific verdict regarding N-9 and HIV.
Carefully controlled studies are also needed to assess the
relative value of the different formulations of N-9 in preventing the
transmission of STDs, especially HIV. Ongoing studies of N-9 film in
Cameroon, and N-9 gel in Kenya and other parts of the world, will
help resolve the question of which formulation, if any, works best.
Question: How close are we to having another female-controlled
chemical barrier method?
Answer: Because of the uncertainties about N-9, and the desire to
have a microbicide without spermicidal properties, developmental
research is under way to discover new microbicidal agents (see
article on page XX). Research is addressing not only new chemical
methods, but also new physical barrier methods that protect the
cervix.
New chemical methods under study include a buffer gel that
maintains a low vaginal pH and does not disturb the normal vaginal
flora; sulfated polysaccharides designed to prevent adherence of HIV
and chlamydia to cells in a woman's reproductive tract, yet are not
spermicidal; N-docosanol, an antiviral product that works by
inhibiting lipid-enveloped viruses; C31G, an amphoteric surfactant
that disrupts cellular membranes but causes less irritation to the
epithelium than N-9; and squalamine, a steroid-based compound that
affects cell growth. These and other agents will undergo phased
clinical studies over the next several years.
Question: Why not emphasize two methods, one for preventing
unintended pregnancy and the other for preventing STD/HIV?
Answer: Clinicians promoting dual contraceptive use must weigh the
interacting factors of extra cost and effect on user compliance.
Clients usually attach different priorities to preventing either
pregnancies or infections, and these priorities may change over time
and among relationships.
Studies on dual-method use are limited and have focused on
the use of the male condom added to the mix of other methods of
contraception. In general, based on investigations where participants
were using primary methods other than the condom, the more effective
the primary contraceptive was in preventing pregnancy, the lower the
level of consistent condom use. For example, a study in the U.S. city
of Baltimore showed only 6 percent of the women who were sterilized
were also using condoms consistently to prevent STDs.
Several reasons can explain why condom use may be low among
people already using an effective contraceptive method. First, many
people -- even those with sexual behaviors putting them at risk of
STD -- see pregnancy as a greater immediate threat. Thus, having
taken precautions against unintended pregnancy, they may be less
motivated to undergo the extra effort and expense of using condoms.
Second, those who are sterilized or who are using implants,
injectable contraceptives, or IUDs do not have frequent reminders to
use contraception. People who depend upon barrier methods or the
daily schedule of taking oral contraceptives may be more aware of,
and prepared for, prophylactic needs. Without regular reminders of
the need to protect against both pregnancy and STDs, individuals may
be less likely to have condoms available.
The way in which counselors and clinicians encourage dual
methods can influence whether the message is effective. With
spermicides as the primary contraceptive method, the percentage of
consistent condom users varied dramatically among three small
clinic-based studies in Mexico, the Dominican Republic, and Kenya.
This indicates factors other than the method itself affect levels of
concurrent use.
In addition, among Colombian commercial sex workers, women
counseled to use spermicides as a backup method if their clients were
unwilling to use condoms were less likely to use condoms consistently
than women encouraged only to use male condoms. More research is
clearly needed on the best mix of contraceptives. Studies that
examine the use of the female condom, diaphragm, or spermicides in
conjunction with long-term methods will help clarify this issue.
What are the key messages regarding use of barrier
contraceptive methods to achieve better reproductive health? First,
encourage correct and consistent use of condoms. Second, maintain
hope (albeit with appropriate scientific skepticism) that research
will show N-9 can be used effectively against HIV. Third, support
developmental research of other female-controlled contraceptive
barrier methods and microbicides. Fourth, evaluate ways to increase
dual-method use to prevent both unplanned pregnancies and STD/HIV.
Dr. Cates, FHI's corporate director for medical affairs, is
an epidemiologist. He previously directed the Division of STD/HIV
Prevention at the U.S. Centers for Disease Control and Prevention.
Copyright 1996, Family Health International.
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