Thursday, January 31, 2008

Evidence-based medicine

A family practice physician I am acquainted with wrote the following about evidence based medicine. Reposted with her permission.

I am young enough to have trained in the era of "evidence based medicine" (EBM) where we attempt to only do those things that have evidence to back them up. In EBM, the gold standard is the randomized controlled double blinded study (RCT) Study subjects are assigned to one group or another randomly, the groups are monitored "controlled" so that you get a relatively similar type of people in both groups, and the results are interpreted by a researcher who doesn't know what group your were in, and the study subjects themselves don't know what group they are in.

This works great for a new medicine, for example, where you can make up 2 identical white pills to give someone, but not so well for behaviors. How on earth would you randomize someone to UC, and expect them not to know it? With the lack of RCTs to use, we are left with case studies, population studies, and case control studies, all of which have inherent flaws. This doesn't mean they don't provide useful information, but since they aren't randomized, you never know if there isn't something special about the group that made them choose the behavior you are studying. (For example, if only well-educated women breastfeed, and then their babies have higher IQs, it's hard to know if it's from the breastmilk, or from having better educated parents.)

The other thing that I feel is absolutely vital to remember about evidence, is that just being scientific doesn't mean there aren't belief systems attached to that evidence. Why do things get studied in the first place? Who pays for it? Who benefits or is harmed by results? There is no "evidence" that is completely objective. It isn't "science" vs. "belief"; science is just another type of belief.

I do not suggest that we need to ignore what evidence we have, but an individual will always need to make his/her own decision also taking into account their beliefs, values, background, relationships, fears, etc. Just because someone does something that seems to go against "evidence" doesn't automatically mean they are making a bad decision. I encounter this every day in my family practice. Sometimes, I have great evidence based reasons for wanting to offer a certain treatment, but my patient has even better life based reasons for declining it, or doing something else.

Even if the evidence were ever to come to light that intentional UC isn't as "safe" as another type of birth, there may well be highly intelligent people who continue to choose that type of birth for their own reasons. Having no such evidence at this point (or in all likelihood, such evidence may never be available) women will continue to make their decisions based on evaluating what evidence there is and taking into account the many other areas of their lives that are impacted by birthing choice...

And a clarification of some of the earlier points she made:

[It is important] to consider how evidence is collected, whether it has relevance to the situation you yourself are considering, and whether it is accurate. Also, it is vitally important to remember that although in the age of evidence based medicine, we purport that "evidence" is somehow completely objective, in reality it is not, nor can it ever fully be disconnected from the social constructs from which it arises. Science and even "evidence based medicine" are themselves belief systems. I happen to live in the world where evidence is very important, and I try very hard to stay on top of the latest and greatest, and I very freely share every bit of evidence I'm using in making a recommendation with my own clients. But I also recognize that evidence will never be the sole factor in any decision made by a real person, nor should it be, nor should I feel any personal discomfort if someone receives my knowledge of the evidence, and chooses to do something other than what I recommend.


  1. Thanks for the article Rixa and the nice FP doctor :)
    It reminded me of an interesting little tidbit about the higher IQ related to breastfeeding or the mothers' education level. I once saw a population study that tried to eliminate this problem. It was a sibling study: they collected pairs of siblings where one was not breastfed and the other was (or there was at least a 6 mo diff in the duration of bf) and they looked long term for health effects. None of the health benefits claimed for bf were found, except for the higher IQ! It was even a graded 'dose responsive' effect: more breastfeeding in months, more higher IQ. Hm.

  2. Very good points. This is why I don't trust many "studies," too often there's no way of knowing if the test groups were diverse and the testing fair.

    Most people who UC, or even just homebirth, are off the radar anyway, so it's practically impossible to garner a good representation of the outcomes in an official "study." I suppose that's why so many in the medical field deem it unsafe, because the only results they see are the ones that failed. They don't see the X number of GOOD outcomes, because there's no one writing it down on a clipboard.

  3. I don't mean this post to dismiss any and all medical studies, of course, just to point out the limitations of that one kind of evidence.

    The Cochrane database is a good place to visit to be updated on what we do know from RCTs about pregnancy and birth. I think I have a link to it on my side bar.

    Another issue I am interested in is how long it takes evidence from such RCTs to filter down into clinical practice. For example, we now know from several RCTs that AROM doesn't shorten or speed up a normal, spontaneous labor (which is the reason that it's often done routinely). That's good to know. But how many midwives or physicians will change their style of practice because of that? We're still dealing with the practice of episiotomies even though we've known for how long?--at least a decade or two--that their purported benefits don't stand up in the medical evidence. And yes, the rate has dropped in the last several decades, but it's still somewhere in the neighborhood of 25% (anyone have a more accurate number?).

  4. Two thoughts:

    Jill -- In Saskatchewan we're on the verge of regulating midwifery. Midwives will be employed by govt-run health regions (and paid by the govt) and they will be required to call the hospital and tell them when their clients are in labour. While the call timing will have to be judicious, the record of these calls will make the medical establishment here aware of how many homebirths are successful -- someone WILL be writing it down on a clipboard.

    Rixa -- Regarding the filtering-down of medical research results: some universities are developing institutes or depts or units devoted to "translational health," (also translational science or clinical translation), with this very purpose of figuring out how to get the research/science put into practice. Iowa has such an institute and so does my univ in Sask. There's a PhD student in the Iowa geog dept doing her dissertation about translational health geography. Often the focus is on deploying resources, but obviously education should be an important feature as well.

  5. "I suppose that's why so many in the medical field deem it unsafe, because the only results they see are the ones that failed. They don't see the X number of GOOD outcomes, because there's no one writing it down on a clipboard."


    I would appreciate it if the homebirthmidwife would just call the hospital I work at and tell us what is going on. That way, I can keep an OR open. Keep the Doctor on call in house. If everybody is on the same page and has a heads up, that will make things safer.

    I have worked with CNM's who have had successful homebirths. I know that most of the time if you leave it alone it will be fine. But complications do arise often enough to warrent concern.

  6. Chris,
    It's too bad that more midwives don't feel free to do this (fear of legal repercussions, especially those who live in alegal/illegal states). Continuity of care and open communication surely would benefit everyone, but the climate in many states towards midwifery can make this difficult.

  7. Thanks for posting this. One thing to keep in mind when looking at homebirth outcomes/studies is that we live in a culture that does not support homebirth (let alone UC). Going against society in any area of our lives can be stressful. A woman who has endured intense criticism throughout her pregnancy may end up having "problems" in her homebirth that might not have occurred had she instead been encouraged and supported by her family/community.

  8. Rixa answered Chris before I could....unfortunately, in some states midwifery is not legal, so the results would still be flawed. Even in states where it IS legal, there is still fear of prosecution.

    So, it is a good idea in theory, but I don't think it will play out that well. It will be interesting to see how it works in Lynette's area.

  9. laura shanley,

    I don't understand - what kind of "problems"? Can you give some examples?

  10. If you call the hospital, you do not have to give me your name. Ask for the Charge nurse on Labor and Delivery. Tell her you are homebirthing. Tell her your ob history. Then if you have an emergent transfer, the hospital is ready. I am concerned that homebirth folks may go into a community hospital with an emergency and the appropriate medical folks may not be present.

    If you call the charge nurse and say "I have been laboring at home. I have a doppler and my fhr is in the 80s." Well we are going to get the OR ready for if you need it. We are going to make sure every one is on deck.

  11. Chris,
    That makes sense, and that was what I would have done if I had felt the need to transport. Then you're not arriving at the ER or L&D with no notice whatsoever. (I thought you meant that every planned home birth should notify the hospital when labor starts...which seemed a bit overkill).

  12. Or I guess I should ask you, Chris, would you prefer that all planned home births notify the hospital, just as a heads-up? I don't know if that would be overkill or if you'd appreciate knowing. (Of course it might be a bit stressful if the parents or midwife forget to call after it's done with, and you're wondering what has happened! LOL)

  13. I would prefer you call us if we are going to be your transfer hospital. If the call is made during the second stage, that gives us plenty of time to make sure all the resources are assembled. And we are a good transfer hospital because we can get things done really fast and my coworkers are really nice people.

    We all have limited resources. If my charge nures knows a homebirth is occuring 10 minutes away from the hospital, she can plan accordingly.

    You can always call the hospital and have a chat with the Charge nures. You do not have to leave your name. You can use an assumed name.

    Things so smoother is we are aware you are you are out there. I also worry about transfers to hospitals that do not have OB in house 24/7, and a Nicu.

    The hospital I used to work at only had Obs in house if they had someone in labor with an epidural. NCB they did not have to be in house. Therefore, we did a lot of NCB. But if an emergency came through those doors without warning, there was no way we could do a stat c-section. That is one of the reasons I have left that hospital.

    So research the hospital you will transfer to if you need to be transfered.

  14. Chris, thanks for the helpful information. I'm curious about the in-house policy with epidurals--what was the reason for that but not with NCB?

  15. "For every action there is a reaction."

    We believed, back then, that an epidural could increase the need for a c-section. Also once you put in an epidural, you are then managing the labor opposed to letting it play out.

    This was a hospital that had 1:1 nurse labor patient ratio and no central monitoring. So we were very comfortable doing NCB. We also had tub births at that particular hospital.

  16. Wanted to just add a comment on evidence. Although I've written about the limits of evidence-based medicine, I feel strongly that as a health care provider I have an obligation to practice with the best evidence in mind. Although I feel quite comfortable with an individual using things other than evidence for decision making (beliefs, intuition, feelings, etc.) I think that health care providers who assist in decision making for many individuals have an obligation to know and use the evidence that we have. Of course not every area is well researched, and when there isn't any data available I feel we ought to err on the side of not interfering if we don't have evidence that our interference is helpful.
    Of course a health care provider doesn't practice in a social void any more than an individual makes individual decisions in a social void. It's good for me as a provider to be aware of and acknowledge my own biases and strive to not push those on people. One of the things that makes me most disappointed in standard modern obstetrical care is how often there is great evidence available and yet is ignored by so many doctors. Routine episiotomy is a great example, as is continuous electronic fetal monitoring. I know a couple of older OBs who can quote the episiotomy studies, for example, but continue to believe that they are helpful in preventing tearing, or incontinence, or whatever, and so they do them routinely on first time moms. That kind of disconnect between evidence and provider practice drives me nuts. Although I talk about the limits of evidence, it would be a huge improvement if all medical providers just started using the evidence we have!
    I do feel strongly that as a medical provider, though I have an obligation to know the evidence and let it guide my practice, if my clients choose differently from what I'd choose using the evidence, it doesn't necessarily mean they are wrong. Everyone has a different perception and acceptance of risk, or of their own personal hierarchy of beliefs. I try hard not to be emotionally attached to the decisions of my clients. I provide information and experience, and they make the best decisions they can. I've been lucky in that it's rare to encounter a client who wants to do something so far from what I believe is right that I just can't support them. Some of that, I think, is just luck but some of my ability to reach accord with my clients I hope comes from my ability to explain myself well and help clients use the evidence to their benefit.


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