Women want to know: Does using hormonal contraception increase HIV risk?

17 Feb

Women everywhere want, need, and deserve to know if their contraceptive method increases their risk of acquiring HIV.  This question is not new; for years, there have been equivocal studies on the topic, some pointing towards a potential association, others showing no association.  The topic got new attention in July 2011, when results were presented at the annual AIDS conference in Rome that indicated a potential two-fold increase in HIV infection rates among women using an injectable form of contraception, DMPA (brand name Depo-Provera, a kind of contraceptive that uses a hormone called “progestin”) compared with women who used no hormonal contraception and again in October 2011 when it was published in The Lancet Infectious Diseases. (The study failed to show a significant increase in risk of HIVamong women who used oral contraceptive pills, but it’s not clear if that has more to do with a lack of effect or was simply because so few women in the study were using pills).

In response, a meeting was convened by the World Health Organization (WHO) from January 31st – February 2nd, 2012 to reassess the state of the evidence and to determine if recommendations about the utilization of hormonal contraceptive methods should change for women at high risk of HIV.  Currently, there are no restrictions on the use of any hormonal methods for women at high risk of HIV.

At the meeting, the expert group determined that there was insufficient evidence to change who is eligible for using all methods of hormonal contraception, including “progestin-only” methods like DMPA, although they did add a strongly worded clarification statement reminding health providers and programs that women at high risk of HIV must use condoms consistently and correctly in order to decrease their risk of acquiring the virus.

So, does hormonal contraception, and specifically DMPA, increase HIV risk?  Unfortunately there is no clear answer to that question.  There have been studies in animals that have pointed to potential biological mechanisms for an increased risk of getting HIV while using injectable progestin contraceptive methods like DMPA, so there is a plausible reason to expect an effect.  However, many animal studies of HIV have led us astray in the past.

Looking at the research that has been done looking at humans, some studies show a connection, some show none.  Further muddying the water is that all the studies are observational, not randomized controlled trials (Wikipedia has a good explanation of what a randomized controlled trial is here, but for our purposes it’s a study where people are randomly assigned to a treatment group, in this case either DMPA or oral contraceptives, or an IUD, or condoms.  The main strength is that all the many variations in behavior and biology that can impact results should be equally distributed between the groups and in a way cancel each other out).

When we rely on observational studies, it is much harder to feel confident that we’ve taken into account all the individual factors that can affect the results.  For instance, perhaps women who choose to use DMPA as their contraceptive method are less likely to use condoms than women who use only condoms as their contraceptive method (in fact, we have good evidence that this is true).  When you compare the two groups, you may find more HIV infections in the group using DMPA, but it could be because they are less likely to use condoms than the group of women who rely solely on condoms to avoid pregnancy. There could also be other factors of which we are unaware that are different between the two groups and explain the difference.  The researchers often try to “control” for factors like this statistically, but it is extremely hard to know whether data on condom use (or other sexual behaviors, like number of sex partners or frequency of sexual activity) has been accurately reported.  Just like I exaggerate how often I floss my teeth every time I go to the dentist, and my diabetic patients don’t always spontaneously report the cookie they ate right before coming to the office and having their blood sugar checked, women who are seeing medical staff may not give an accurate description of how often they use condoms and with how many partners they have sex, especially if they have been told over and over how important condom use and having fewer sexual partners is to reduce their risk of HIV.

So where does this leave us?  The disappointing news is that, in 2012, science still doesn’t have a clear answer for us on whether use of hormonal contraception, and specifically DMPA, increases a woman’s risk of contracting HIV, although the experts at the WHO were reassured enough by the evidence that we do have to continue to recommend unrestricted use of hormonal contraceptives for women at high risk of HIV.  Also on the bad news front, many women in high HIV
prevalence settings have few or no other contraceptive options, so they can’t simply hedge their bets and switch to something else with a more clearly established safety profile (like oral contraceptive pills), or to non-hormonal methods (like copper IUDs or sterilization).

However, there is lots of good news.  What we lack in clear answers regarding injectable contraceptives and HIV acquisition is made up for in knowledge of other ways to impact the epidemic of sexually transmitted HIV.  We know that people who know they have HIV are more likely to use condoms, so we need to work on getting voluntary testing for everyone, everywhere.  We know that people who are on treatment are much less likely to transmit the virus to their partners, so we need to get everyone access to treatment; shockingly, less than half of people in need of treatment worldwide currently get it.  And we know that consistent, correct use of condoms greatly reduces the risk of HIV transmission, so we need to work much harder at helping people get over the many barriers that exist to using condoms all the time.

We need to keep offering women as many options as possible for family planning.  Women can safely continue to use DMPA.  The bottom line is that, whether DMPA increases HIV risk or not, condoms are an absolute necessity for all women at high risk of HIV, whether or not they are using hormonal contraceptive methods.

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