NBME 22 Case-control study (NBME Answers)

Retired NBME 22 Answers

nbme22/Block 3/Question#34 (reveal difficulty score)
The risk for hemorrhagic stroke from drug X ...
Case-control study 🔍 / 📺 / 🌳 / 📖
tags: biostats

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submitted by sunny(9)

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why is this not a cross sectional survey? ... since we are asking at a particular time

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drdoom As Aristotle once quipped, “A ‘single-point in time’ doth not a cross-sectional study make.” The design of a cross-sectional study would not define “ahead of time” two cohorts (two groups); said another way, a cross-sectional design would not “split people into two groups.” In the design of a cross-sectional study there is only “one group”, and then you ask all members of that group some question (“Do you have asthma?”). At the end of a cross-sectional study, the authors will be able to make a statement like this: “We called 10,000 phone numbers with area code 415 at random and asked ‘Do you take Drug X?’ 500 responded ‘I don’t know’, 633 responded ‘Yes’, and 8,867 responded ’No’.” +19

castlblack That is interesting. I think the question is phrased ambiguously. I interpreted the question stem to say that they called random people and sorted them into hemorrhagic stroke pts vs controls after the fact using an ORAL questionnaire. Therefore the question would be " Did you have a stroke?" Yes = 702 or no = 1376. And thus would be a cross-sectional study. I see now that the questionnaire must be paper and contacted from some unstated list of drug X recipients. +

jatsyuk38 Yea I thought the same thing you did. They could of randomly called people and asked "have you had a stroke" followed by "have you taken drug X" and to me that is cross sectional. Especially when most cohorts (at least in Q stems) have equal numbers of controls and those with disease and in this case they dont. But I think when they explicitly say "control subjects" you know it is cohort, as in cross sectional you get control sort of accidentely when they say "no, I haven't had a stroke" - sorry if this made things more confusing +

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submitted by ∗fexx(23)

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I got this wrong but Case contrOl (O for Odds ratio): compares group who has DISEASE vs no disease - trying to find out what caused it CohoRt (R for Relative risk): compares group with RISK FACTORS/ EXPOSURE vs no exposure - trying to figure out if they will develop disease

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submitted by ∗bubbles(79)

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So...case-control studies compare a group of people with the disease and a group of people without the disease. I'm not sure I understand why you can call people randomly and call that a control group. What if among those called randomly, some of them have also had hemorrhagic strokes?

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impostersyndromel1000 this is one of those Qs where you just dont over think it and focus on your first point, that they are comparing a group with the disease vs (potentially) one without it. Thats what i took from it at least (sorry fi this is too late) +3

tiagob Why is not Cohort ? since it compares groups exposed to drug X? +

djinn Cohort studies determines end of disease and CC determines begins +3

drdoom ^^^ “don't overthink it” is not a viable strategy; it doesn't constitute thinking and i hate when people use it as a replacement to saying, "i have no idea how to think about this problem and so i guessed and got lucky" +2

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