posted
Since this next post will be at the top of the page, I'll repost the questions for Orincoro (should he be interested in wending through the murky world of statistics in clinical studies with me):
quote:1. First, what is your sense of what is meant by "controlling for?" That is, how do you think that process works?
2. Secondly, do you have the same concerns about heart medications (and why or why not)?
More details and fleshing out of what I'm asking is on the prior page, some half dozen or so posts from the bottom. Meanwhile, I'll start writing up my thoughts offline.
Looking-for-some-answers, please do let us know that it all turns out okay. I have my fingers crossed for you.
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quote:Originally posted by ClaudiaTherese: scifibum, what's the scoop on the person who posted that there was "not a single shred of evidence to suppport" the possibility of any other additional means of action for EC, other than by preventing ovulation? Is this a person with a medical background, do you know? And are Ornery forum regulars generally accepting of claims of fact without calling for supporting citations?
To the first question, well, no medical background that I know of.
To the second question, uh, sometimes. I would not say the forum regulars are generally credulous, though you've now seen a good example where several of us were.
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rivka, the finality of your policy provokes my curiosity, when combined with the fact that something led you to read a lot of discussions there. Some kind of horrified fascination that you don't wish to repeat? Posts: 4287 | Registered: Mar 2005
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quote:Originally posted by scifibum: To the second question, uh, sometimes. I would not say the forum regulars are generally credulous, though you've now seen a good example where several of us were.
Well, there are always several factors at play. Sometimes people are talking more casually than not, sometimes it's someone who you know is well-versed in that area, and so on. I wouldn't say "credulous" myself, more just "informal." And there is nothing wrong with informal in the right context.
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Edited to add: I'm just constitutionally unable to be informal about medical things because it is my area of professional training. About all other sorts of things, I have little more interest or background for anything but informality. You'll rarely find me formal about much, other than this (and academic philosophy, I guess -- but those are but two slim slices of the world, for certain).
quote:Originally posted by ClaudiaTherese: Sure, a pleasure.
1. First, what is your sense of what is meant by "controlling for?" That is, how do you think that process works?
You take the group of people you would like to study- perhaps women who are avoiding pregnancy between the ages of 25 and 30, representing a cross section of the population, and divide it in half. Half take the EC, half don't, and you study the results.
quote: 2. Secondly, do you have the same concerns about heart medications (and why or why not)?
Well, medication for heart conditions could be studied amongst a cross section of the population that shares the same observable condition. Also, medications for heart conditions are easily regulated (unless you are talking about emergency medications), with the patients taking the same pill at the same time, every day. It's much easier to determine long term outcomes because either the patients die earlier or later, proving that the medication is either working or not working. If you were trying to determine what the mechanism of the medication was, you could have concrete ways of studying that, by looking at the long term effects of the medication on various aspects of health.
But with EC, each patient in the study group would only use the medication once or twice, and the chances of implantation of a fertilized egg are not extremely high in all cases to begin with. I understand that you could see a statistical effect for EC in a large study, but how could you use the study to pinpoint the mechanisms of EC, given other factors? Maybe I'm just don't have a statistician's training, so the answer could be obvious, but I don't see it.
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quote:Originally posted by rivka: Something like that. In the sense of rubbernecking at a truly gory accident.
I've tried to read at Ornery, but the politics and personality are so baroque, I could never follow a thread.
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quote:Originally posted by Orincoro: You take the group of people you would like to study- perhaps women who are avoiding pregnancy between the ages of 25 and 30, representing a cross section of the population, and divide it in half. Half take the EC, half don't, and you study the results.
What's the "controlling" part, in your view? Where does that come in?
quote:
quote: 2. Secondly, do you have the same concerns about heart medications (and why or why not)?
Well, medication for heart conditions could be studied amongst a cross section of the population that shares the same observable condition. Also, medications for heart conditions are easily regulated (unless you are talking about emergency medications), with the patients taking the same pill at the same time, every day. It's much easier to determine long term outcomes because either the patients die earlier or later, proving that the medication is either working or not working. If you were trying to determine what the mechanism of the medication was, you could have concrete ways of studying that, by looking at the long term effects of the medication on various aspects of health.
I don't see any of this as distinct from heart medications (e.g., blood pressure), other than time of day. Time of day generally isn't much of an issue for blood pressure medications, compared to "individual physiologies" and widely variant things which cause stress (seeing an ex-boss, sex, reading a book that moves you to tears, etc.). It's actually much harder to study medications carefully over time than a one-time dose, because a lot of individuals in a group will always miss doses or fudge on the timing (and time between doses makes a much bigger effect in general than time of day, for most meds).
It's also much harder to track a assess multiple effects than a single effect. "Various apects of health" as outcomes rather than just a yes/no answer (like ovulation vs. no ovulation) makes for a dirtier study, not a cleaner one.
Regardless, for many studies of mechanism in EC, the subjects were women enrolled in a study in advance, in which the effect of the medication was studied in a pre-determined way. They were enrolled to either a treatment or placebo group, with the understanding and consent that a pregnancy could develop this cycle.
quote:But with EC, each patient in the study group would only use the medication once or twice,
*grin
This is good, not bad, from a research point of view, because it reduces the variables and reduces the effect of individual error.
quote:and the chances of implantation of a fertilized egg are not extremely high in all cases to begin with. I understand that you could see a statistical effect for EC in a large study, but how could you use the study to pinpoint the mechanisms of EC, given other factors? Maybe I'm just don't have a statistician's training, so the answer could be obvious, but I don't see it.
Again, many of the EC mechanism studies were done in situations that were non-emergency, especially early on. Women took the medication (or a placebo) and had their ovulatory hormones tracked and/or ultrasound to identify follicular development. There are specific hormonal spikes that occur at the time of ovulation. The outcomes measures weren't just pregnancy vs. non-pregnancy, but well-tested tracking methods of ovulation vs. non-ovulation.
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Just to get a better sense of what is troubling you: so, what about medications given in trauma situations? People who've lost a limb vs. crush injuries to a kidney vs. head injury, people who are fat, thin, old, young -- some of the very same standard medications are used, and there is no perfectly standardizing those situations.
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I'm hoping this doesn't feel too much like you being put on the spot, but that it feels more like an ongoing conversation. I'm not sure still how far back to go into the details of setting things up, as we seem to consider different things as positives or negatives (such as one-time dosing versus dosing over time). It's hard to answer questions I don't really know in advance that you have, so I'm trying to tease that out.
I will put some orientation up as background later today, too.
posted
Well, I' just curious how medications are studied in the first place. From all I have learned about studies, there are so many difficulties, it's a wonder we ever get any medications that do what's intended in the first place.
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An even better example would be medications to treat heart attacks or pulmonary emboli, which are clots in the lung. Unlike with ovulation, there isn't a "natural" process that can be studied as to effect of a given medication. We can't deliberately start heart attacks or emboli just to study them, obviously, and there is no healthy equivalent or marker to study instead of the trauma itself.
Stats itself is weird. For example, it's counterintuitive that a sample size of 500 people is just as useful for studying a group of 15 million people as it is for studying 100,000. Adding additional people to the sample would not improve the estimation of what is going on in the group of 15 million, because the effect is negligible at that point.
There's an old saw about democracy: something like, "It's the worst and messiest political system, except for the alternatives." Pretty much suits this situation, as well. And yet modern medicine as a whole saves and improves lives, and life in general would be shorter, more painful, and much less without it.
Some of the most interesting new research has gone ultra-low-tech, such as using mirrors to treat phantom pain. If I have the stamina, I'll talk about that later. Right now, though, let me finish pulling together "what I wish everyone understood about assessing medical studies," or something like that. It may not answer your specific questions (and it may take one or more courses to have those answers make sense, well beyond my commitment level here), but it may be useful background.
Medical school doesn't usually prepare physicians well for assessing research. I happened to go to a medical school where research was stressed equally as much as clinical knowledge and skill, and my residency program was one which had a necessary research component. Furthermore, I did a 2-yr research fellowship through the NIH, and I married a researcher. And I am still learning!
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posted
So I take it that it boils your blood too to see medical and science "headlines" in the news. I've heard from some doctors that it is reporters who shape the greatest part of the public perception of most aspects science and medicine, and it's something like asking a kindergarten student to tell you about what it's like to be a teacher.
I suppose it's like anything where you have to watch the media misunderstand and misconstrue everything- except medicine is one of those areas where the media can do actual harm to people through their misunderstandings.
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posted
According to pregnancy tests I took last Sunday and today, all signs point to negative! Hoorrrayy! I haven't been having any symptoms recently either, since the EC seemed to have worn off, so I think I'm safe in saying I'm not pregnant.
Thanks again everyone, for everything. It was quite a relief to get some good advice and reassurance here. I appreciate the support- this was a scarey last few weeks.
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