Drs Jenna Beckham and Thomas Kimble discuss the safety and efficacy of contraceptives for patients with a higher body mass Index (BMI).
Jenna Beckham, MD, MSPH, FACOG: You mentioned patients with higher BMI so what are you thinking about in terms of additional safety concerns when selecting contraceptives for patients with a higher BMI?
Thomas Kimble, MD: When I consider my patients with a higher BMI it's a twofold consideration. There is the safety consideration then there's also the efficacy consideration. As far as safety, estrogen increases clotting factors that are produced by the liver. It causes some changes in the endothelium in the vascular system. It also increases triglycerides and may affect glucose metabolism those are some of the things that estrogen can do that can lead to other cardiovascular risks, so you have to be careful in that group. Women with higher BMIs, because they have higher BMIs are also at increased risk for all of those so that's why we must be especially careful in that group. Well then there's the efficacy concern as well; there is a known inverse relationship between BMI and the serum levels of some sex steroid hormones.
Jenna Beckham, MD, MSPH, FACOG: Then the specific sort of weight recommendation for the patch not being as effective in patients who weigh over 90 kilograms; some of the other data is a little bit more mixed. Like a lot of things, you can find one study that says maybe some decreased efficacy with the combination pills or the ring and others that didn't show a difference. I think about in these patients too, the flip side of the coin is thinking about pregnancy. Again, more when you're thinking about the risks of using those things and there are some risks but for those patients with higher BMIs that they also have other medical comorbidities and pregnancy may be also risky for them so finding that right balance. As you said, also making sure that they're well counseled and understand if there's even potential for decreased efficacy that they know that exists. Ultimately, they can still choose to use that method but to be aware before selecting a certain method.
Thomas Kimble, MD: In addition to safety and efficacy, there's also another, third consideration and that's some socio-economic nuances. I say that because oftentimes when I'm doing a birth control lecture, I kind of give this little anecdotal study on one of my collaborators that I do a lot of research studies with. She was doing a clinical trial on a birth control pill and they had some failures meaning that there were some women in this clinical trial who got pregnant while taking this birth control pill. She did a pharmacokinetic study to figure out what was going on and they looked a little closer. What they saw was that the people who failed were more likely to have a higher BMI. Now initially that kind of sent a little ripple through the contraception world; oh my gosh are these products not working in women with higher BMIs? Well, when she did the pharmacokinetic study she put women with higher BMIs on a birth control pill, did a control group of women with normal BMIs on the same pill. They had to come in, as a pharmacokinetic study, every couple hours at first to have their blood drawn, then daily. What was very interesting is that in the study group, the women with higher BMIs, there were several participants who their serum levels of the estrogen and the contraceptive hormones were zero. Not lower like we were worried that they would be but zero; what that meant was that they weren't taking the pill. The take home that we got from that was well maybe there's something going on that is making it more difficult for these patients to stay on a schedule to take their pill every day at the same time. They may have other socioeconomic factors in their life as far as their work or their daily schedules that aren't what other people have that help them keep a daily schedule and keep on track. We rely on our schedules to help us to remember to do things like take our medicines including our contraception and maybe there is less of a daily routine or a daily schedule in this group. Those are just some of the other considerations on why other non-estrogen or maybe even our long-acting reversible methods may be a better option in women with higher BMIs.
Jenna Beckham, MD, MSPH, FACOG: Certainly, in those patients but in all comers remembering to take a pill every day can be challenging. Some patients, I'm sure you've seen it, will say upfront I want to take the pill. That's what I've heard about, my friends are taking it, it'll be fine and then they come back to you several months later and they're like this is hard. I keep forgetting them. Can we talk about some of those other options, and I just always try to validate them. It can be hard. It seems like sitting in the office, taking a pill every day is a low hanging fruit, but life is busy for many of our patients and sometimes that goes by the wayside like you said having some of those longer acting methods eliminates that, at least that part of the equation.
Transcript edited for clarity