We have a sample of arrhythmic patients, with several control groups. We are using blood pressure as one of the stress-measurements. We are not interested in blood pressure levels per se and we don't have control variables such as weight and height (BMI). We also don't have blood pressure data in "raw" form where Hgmm or some other standardised measure can be used. We have the continuous data which the program creates.
We used BioPac in the recording of the blood pressure.
Set-up is following: each mental stress test section is controlled by the rest level. Is this sufficient way of controlling the variables, or is there other good way to do it? As mentioned, BMI is not known and the age of different groups are not standardised and thus the baseline levels are not anywhere close to each other. Also it is not guaranteed if there could be some other adjustments which could effect the baseline of the blood pressure. Thus, we have to rely on the controlling the blood pressure variables with the rest level. I would like to know if someone has any more sophisticated methods for it?
I would be glad for any answers and I will answer if you have further questions related to this question.
I can understand it is a difficult design and many confounding variables may affect the study. I may suggest for your study to consider the BP for each case as the control and then examin the effect of your intervention on the same case. you may do Paired sample test for analysis. Hope this is useful. good luck
I agree that there are many confounding variables. What is your hypothesis?
Does anything happen between the first measure and the last? Is there a way that you could think about this in terms of reactivity and recovery? This is an important topic in cardiovascular research. If you have other data you could look at what predicts increases, decreases and stability in blood pressure.I am not sure if you could calculate slopes which are more stable than change scores.
I agree that there are many confounding variables. What is your hypothesis?
Does anything happen between the first measure and the last? Is there a way that you could think about this in terms of reactivity and recovery? This is an important topic in cardiovascular research. If you have other data you could look at what predicts increases, decreases and stability in blood pressure.I am not sure if you could calculate slopes which are more stable than change scores.
Hi Ilmari,
I wonder what is your research hypothesis and what you are trying to achieve: is it comparing the effect of different stress manipulation on BP ?
Howrever, once you have the signals (is it PPG or only ECG ?) Both for the rest mevel and the stress manipulations levels, you can asses the change of BP from the PPG pulse zhape change (we do it all the time). It might not be the most elegabt study shere all variables ade controlled, but it can be useful for a pilot.
Thank you all for the answers. Basically the idea was what Ehud mentioned: comparing the effect of different stress manipulation on BP., and to make it simple, we created a subtraction variable comparing each of the stress tasks. We used mean arterial pressure (MAP) and pulse pressure (PP).
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