I would appreciate your advise regarding the testing of variables for possible confounding.

I have 12 possible independent variables on ordinal and nominal levels. My dependent variable is functional dependence (mRS≥3). Before i perform regression analyses, i would like to test if there are possible confounders among these 12 variables.

My question is HOW TO test if these 12 variables are possible confounders in a relationship "cognitive functions" ------------->functional dependence (mRS≥3).

Thank you very much for your answer and your time.