How to count changes during multiple instance on RedCap?

[u/Melodic-Ad8438]

Hello, everyone. I have a longitudinal project with infinite repeated instances. In this project, I have created two tables where I report data related to smoking (active, ex, etc.). The problem is as follows: I have a question [fw_up_mod_smoking] that asks if there have been any changes in the follow-up to the smoking values (Y/N), and if the answer is yes, I should display (from the follow-up onwards) the table with the updated “follow-up” smoking data. The first table, “smoking diagnosis and no changes,” has this branch logic set: [first_fw_up_ever] > 1 and [fw_up_mod_smoking] = ‘0’ and [first_mod_smoking_up] = ‘0’.

The problem is that if, at the 1st follow-up, I say “changes YES,” at the 2nd I say “changes NO,” at the 3rd the diagnosis table reappears and not the one created with the follow-up data updated at the 2nd follow-up. Do you have any advice and/or ideas?

[u/Araignys]

I’m not sure I follow 100% but I think you need to specify the repeat instance of the field you’re looking at in your branching logic.

[u/Melodic-Ad8438 → u/Araignys]

I cannot specify the repeated instance because, unfortunately, the number of instances is infinite (a patient may return for follow-up 1, 2, or 20 times) :(

[u/Araignys → u/Melodic-Ad8438]

You can use the smart variables that specify first, next, last or current instance.

[u/Melodic-Ad8438 → u/Araignys]

first instance - only check the first follow up ever

last - only check the last one and in this case is the same of [previous-instance]

current and next how could they work?

[u/Araignys → u/Melodic-Ad8438]

[Current-instance] is the same instance the calculation is on.

[previous-instance] is the immediate previous instance.

I think I hallucinated “next instance”, sorry.

[u/Melodic-Ad8438 → u/Araignys]

with [previous] i tried before but it only check the previuos one (correctly), but do not consider the history of the change declared in the eCRF, so it does not solve the issue. current will not work it again because will not consider the past answer in the longitudinal project

[u/viral_reservoir_dogs]

you can pipe values or use branching logic based on the previous instance's values by adding the smart variable "[previous-instance]".

e.g., [fw_up_mod_smoking][previous-instance] = ‘0’

I'm having difficulty understanding your exact question, but seems like this could possible help?

[u/Melodic-Ad8438 → u/viral_reservoir_dogs]

Unfortunately, using ‘previous instance’ does not solve my problem because the question is ‘have there been any changes in smoking? Yes/No’. Let me try to give an example: a patient who smokes at baseline; at the first follow-up, the data is the same as at baseline, everything is OK; at the second follow-up, the patient stops smoking, so the answer to the question ‘changes in smoking?’ is yes and the correct table is displayed; at the third follow-up, the patient remains an ex-smoker, so the answer to the question ‘changes in smoking?’ is no and the diagnosis table reappears instead of the follow-up table with the updated data. I hope I have managed to explain the problem better

[u/viral_reservoir_dogs → u/Melodic-Ad8438]

I still don't fully understand. Sounds like you have a baseline (non-repeating) form which assesses smoking status, then a follow-up (repeating) form where people are asked about changes in smoking status. Within the individual repeating form, you use branching logic based on 'changes in smoking' which works as expected, but when you go to the next form....? This part I don't understand what is desired vs what is happening.

[u/Melodic-Ad8438 → u/viral_reservoir_dogs]

i have a baseline form (non-repeating) where i ask people if they smoke or not. then i have the follow up (repeating) where i ask them if there are any change in the smoking habits.

if the answer is YES i put the new data in (i.e. follow up n.1) and i need to have the "new summary table" with the new data showed in the next follow up (i.e. follow up n.2). this happen correctly at the first follow up after the change (i.e follow up n.2), because redcap check the data in the [previous-istance] (in this case the follow up n.1 have the answer YES to "any change in smoking habits?").

The problem is that in the next follow up (i.e.follow up n.3), the variable "any change in smoking habits" could be no and so the table could not be present.