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[afro-nets] Hormonal contraception and HIV acquisition study finds no statistically significant association
- From: "David Hock" <DHock@fhi.org>
- Date: Tue, 12 Dec 2006 14:04:09 -0500
Hormonal contraception and HIV acquisition study finds no statistically significant association
You should be aware that a study, published in the January 2, 2007 issue of the journal AIDS (now available on the journal's Web site) has found no overall statistically significant association between the use of either combined oral contraceptive (COC) pills or depot medroxyprogesterone acetate (DMPA) and HIV acquisition. This four-year, prospective study, funded by National Institute of Child Health and Human Development, was conducted among some 6,100 HIV-negative women in Uganda, Zimbabwe, and Thailand. The primary finding of this study provides the best reassurance to date for women in need of highly effective contraception in settings of high HIV risk.
The results from the study do not indicate that any changes should be made in the provision or use of DMPA or COCs. Neither the WHO nor the International Planned Parenthood Federation, which have reviewed the study results, plans at this time to change their guidelines for hormonal contraceptive use.
However, because hormonal contraceptive use has not been shown to protect against HIV infection, hormonal contraceptive users should still use condoms consistently and correctly with each sex act if they are not in mutually monogamous relationships with uninfected partners. Such individuals should also reduce their number of sex partners. These long-accepted recommendations remain unchanged regardless of the method of contraception a woman uses. Meanwhile, both members of a couple should be tested for HIV to learn whether they are infected or not. In most settings - even those with high HIV prevalence - most couples will not be infected. However, in areas of high HIV prevalence, even if both members of a couple are uninfected, condoms should still be used unless mutual monogamy is certain.
The study also explored whether sexually transmitted infections (STIs) modified the relationship between hormonal contraceptive use and HIV acquisition. Surprisingly, it found that among the approximately half of study participants testing negative for herpes simplex virus-2 (HSV-2) at enrollment, those who used either COCs or DMPA had a statistically significant increased rate of HIV acquisition compared to non-users. This finding was unexpected, has no clear biological mechanism, and may be due to chance. Thus, as is often the case with unexpected study findings, further research must evaluate this potential association.
In summary, the results of the present study:
Provide family planning providers, women, and women's partners with important, new, and generally reassuring knowledge about the association between hormonal contraceptive use and HIV acquisition. Do not indicate that any changes should be made in the provision or use of DMPA or COCs.
Serve as a reminder that while hormonal contraceptive use is safe and highly effective for preventing unintended pregnancy, only consistent and correct condom use and mutually monogamous relationships among uninfected individuals protect against STIs/HIV.
A possible relationship between hormonal contraceptive use and HIV acquisition has been investigated in numerous studies. However, understanding of this possible relationship has remained poor. Study results have been inconsistent, in part because nearly all these studies have been designed to investigate other research questions and have had important methodological shortcomings. Also, they have considered different population groups in different regions of the world. Only about 12 prospective studies - which reduce some sources of bias to results - have been conducted on this topic.
The present study, led by Family Health International (FHI) in conjunction with seven other collaborating institutions,* is unique and standard-setting in that it is:
The only large prospective cohort study designed to specifically evaluate the relationship between the use of low-dose combined oral contraceptives (COCs) or DMPA and HIV acquisition. Conducted in Uganda, Thailand, and Zimbabwe, this study involved some 6,100 HIV-negative, 18- to 35-year-old women in three exposure groups (COC users, DMPA users, and women not using hormonal contraception) of roughly equal size. With this number of study participants, the power of the study to detect a potential association was high.
Conducted among family planning clients, who are considered to be at lower risk of HIV infection than other high-risk groups (such as sex workers or members of HIV discordant couples) and are similar to most women worldwide who use hormonal contraception. In contrast, while results of other studies have been conflicting, those that have indicated an increased HIV risk associated with hormonal contraception were generally conducted among high-risk populations of women, such as sex workers.
Methodologically strong in terms of accurate measurement of contraceptive use, identification of the timing of HIV infection relative to hormonal contraceptive use, rigorous and successful follow up of study participants (participants were tested for HIV infection every 12 weeks until they became infected or had been followed for 15 to 24 months; overall retention rate of 91 percent), confirmation of the study outcome (HIV incidence) data via stringent algorithms and laboratory audits, and careful measurement of and adjustment for a large number of potential confounding factors.
For these reasons, this study greatly clarifies the question of what effect hormonal contraceptive use has on HIV acquisition and serves as the strongest study to date exploring this issue. However, international reproductive health experts will continue to evaluate any additional evidence emerging from other studies.
Institutions collaborating in this study were:
Makerere University, Kampala, Uganda;
Case Western Reserve, Cleveland, OH, USA;
University of Zimbabwe, Harare, Zimbabwe;
University of California at San Francisco, San Francisco, CA, USA;
Chiang Mai University, Chiang Mai, Thailand;
Johns Hopkins University, Baltimore, MD, USA;
Family Health International, Durham, NC, USA; and
Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
For further background information, please see: NICHD press release, available:
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